In this article we will discuss about the classification of Tubiflorae. According to Hutchinson, Tubiflorae consists of eleven families:- 1. Convolvulaceae 2. Boraginaceae 3. Verbenaceae 4. Labiatae 5. Solanaceae 6. Scrophulariaceae 7. Bignoniaceae 8. Orobanchaceae 9. Pedaliaceae 10. Lentibulariaceae 11. Acanthaceae.
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Family # 1. Convolvulaceae:
Convolvulaceae are annual or perennial herbs or shrubs, usually twining or trailing, rarely erect and rarely leafless parasite (e.g., Cuscuta, now transferred to Cuscutaceae). Leaves are alternate, simple, entire or pinnately or palmately lobed, exstipulate.
Inflorescence is a bi-parous cyme or cymose or racemose panicle, or flowers solitary, bracteate. Flowers are actinomorphic, bisexual, hypogynous, usually showy. Sepals 5, usually free to the base, quincuncial, often persistent; the outermost sepal sometimes larger.
Petals 5, united to form a funnel-shaped or salver-shaped corolla, induplicate-valvate or twisted in bud; lobes often with median folds. Stamens 5, epipetalous, inserted at the base of the corolla tube and alternating with the lobes of the corolla; anthers 2-celled, usually introrse: pollens ellipsoid or globose, smooth or spinulose; annular or cupular intrastaminal disc usually present.
Carpels 2, rarely 3-5, united to form a superior ovary; ovary 2-celled with 2 ovules in each cell, or 4-celled due to presence of false septa with one ovule in each cell, or when more than 2 carpels are present cells of ovary as many as carpels; ovules erect, anatropous; style 1, filiform, bipartite or not, rarely styles 2; stigma capitate or bilobed.
Fruit a capsule, rarely berry; seeds smooth or hairy, with cartilagenous endosperm; embryo curved with folded cotyledons.
A family of predominantly twining or trailing plants includes a few erect shrubs, rarely attaining tree size. Ipomoea wolcottiana Rose, is a tree often as tall as 10 m. I, arborescens Don. is a large shrub or a short tree. Erycibe paniculata Roxb. is a diffuse shrub or a short tree.
Leaves are simple, lobed or entire, but palmate leaves are found in Ipomoea pulchella Roth.,—the Railway creeper. Flowers are actinomorphic and bisexual, but Mina lobata LI. & L. has slightly zygomorphic flowers and in Hildebrandtia the flowers are unisexual.
Cuscuta is a total parasite. It is leafless and rootless. A corona is present at the base of the corolla formed of staminodes alternating with stamens. This genus is now placed in a distinct unigeneric family Cuscutaceae. Adventitious roots from the nodes of stems come out in many species and in I. batatas Lim, they form tubers which are edible. Extra floral nectaries on the leaves of many species are found.
Presence of intraxylary phloem in the stem is a constant character. Anomalous secondary growth occurs in many climbing species due to formation of successive rings of intraxylary phloem and secondary accessary vascular bundles.
Fibres in the pericycle is usually scanty, rarely in a continuous ring. Vessels solitary or in multiples; inter- vascular pitting is alternate.
Wood parenchyma scanty, paratracheal or apotracheal; fibres are bordered pitted. The family consists of about 1200 species in about 50 genera and is cosmopolitan in the tropical and temperate regions. About 177 species are found in India of which a few are cultivated for large showy flowers.
The floral formula of the family is represented as:
Convolvulaceae is closely related to Solanaceae as well as to Nolanaceae and also to Polemoniaceae, Boraginaceae and Hydrophyllaceae to some extent. According to Takhtajan Convolvulaceae is more allied to Polemoniaceae, Boraginaceae and Hydrophyllaceae than to Solanaceae and Nolanaceae. Convolvulaceae is placed by him in Polemoniales while Sola- naceae and Nolanaceae are included by him in Scrophulariales.
The family is well-known for the ornamental plants with large showy flowers. Ipomoea purpurea Lamk. is the Morning glory. I. pulchella Roth, is the Railway creeper. Many other species of the genus are cultivated in gardens.
I. quamoclit Linn, with linear- pinnatisect leaves and small scarlet flowers is also a garden favourite. I. fistulosa Choisy a recent introduction to this country is found to grow almost everywhere in the plains. The plant is poisonous. Evolvulus nummularius L. is a common trailing herb.
Ipomoea batatas Linn, introduced to Asia from G. America produces root-tubers from the nodes of stem and branches. The tubers are full of starch and forms an important article of food. Root stock of Colystegia sepium Bth. of New Zealand is also edible after cooking.
The leaves and tender shoots of Ipomoea aquatica Forsk. are used as potherb. Exogonium purga Linn, is highly purgative. Operculina turpethum (L.) Mans, yields the turpeth root. Argyreia speciosa Sweet is the Briddha-darak of Indian Kavirajas.
The family is divided into 2 subfamilies:
I. Convolvuloideae:
Leafy autophytes; interstaminal scales absent; cotyledons folded.
II. Cuscutoideae:
Leafless total parasites; interstaminal scales present; cotyledons absent or much reduced.
The subfamily Cuscutoideae is treated as a distinct family Cuscutaceae by Hutchinson.
The conscription of the new-family is given below:
Rootless, leafless parasitic climber with thread-like herbaceous stem. Flowers actinomorphic, bisexual, small, in stalked or sessile clusters. Sepals minute, 4-5, free or united. Petals 4-5, united, bell-shaped; lobes imbricate.
Stamens 4-5, inserted on the throat of the corolla and alternating with corolla lobes; staminodial scales are present at the base of corolla alternating with the stamens, scales fimbriate or lobed.
Ovary superior, 2-locular, with axile ovules in each chamber; styles 2, distinct or more or less connate. Fruit a dry or fleshy capsule, dehiscing irregularly or transversely. Seeds tubercled; embryo linear, curved or spirally twisted; cotyledons much reduced or absent.
The family with the single genus Cuscuta contains about 170 species spread over the tropical and temperate regions of the world. A few species of the genus are Indian and C. reflexa Roxb. is common as pest all over the country in the plains.
Family # 2. Boraginaceae:
Boraginaceae are annual or perennial herbs or shrubs or trees, usually pubescent. Leaves are simple, entire, exstipulate, usually alternate. Inflorescence a simple or double scorpioid cyme, coiled in young stage. Flowers are bisexual, actinomorphic or slightly zygomorphic, hypogynous.
Sepals 5 free or united in a bell-shaped or tubular calyx, imbricate or rarely valvate, usually persistent. Petals 5, blue or white, united in a funnel-shaped or rotate corolla with spreading lobes; imbricate or rarely contorted; throat with scale-like outgrowths. Stamens 5, epipetalous, alternating with corolla lobes, filaments equal or rarely unequal; anthers 2-celled, introrse; an annular nectar secreting disc is usually present.
Carpels 2, syncarpous, forming a superior 2-celled ovary with 2 basal ovules in each cell; often each cell at maturity is divided into 2 parts, so that the ovary becomes 4-celled with ovule in each cell; style usually gynobasic, rarely terminal, when terminal styles often 2; stigma capitate or lobed. Fruit a cluster of 4 nutlets or a drupe. Seeds with or without endosperm; embryo straight or curved with radicle turning upwards.
The family includes herbs as well as trees or shrubs, e.g. Cordia, Ehretia, etc. The herbaceous plants are usually pubescent with thick-walled stiff hairs with cystolith like bodies in the basal region.
Heterophylly is found in a few genera, viz. Pulmonaria, Cynoglossum, etc. where the cauline leaves are different from the radical leaves. Flowers are more or less zygomorphic in Echium and Lycopsis. The style is terminal in the subfamilies Cordioideae, Ehretioideae and Heliotropioideae but gynobasic in others. In Echium the style is bipartite.
Floral formula:
Vessels are often in clusters with simple perforations and the intervascular pitting is alternate. Wood parenchyma is apo-tracheal. Fibres have small bordered pits. Pericycle is usually without fibres. The family consists of about 100 genera and about 2000 species and is distributed mostly in the temperate regions while a good number of species are found also in the tropics. In India 145 species are found.
Species of Myosotis (M. paluslris Bth.) are the Forget me-not flowers of European medows, also available in the Himalayas. Cynoglassum is another Himalayan genus of herbs with small blue flowers. Heliotropium indicum Linn.- Beng. Hatishura is a common weed of the road side in the plains.
Cordia dicholoma Forst the Lasora, a short sized tree is found all over India in the plains. Ehretia serrata Roxb. is another Indian tree found near the foot hills of the Himalaya. Coldenia procumbens Linn, is a prostrate herb common in the dry fields.
The family is not important from the economic point of view. A dye is obtained from Alkanna tinctoria Linn, and also from different species of Arnebia. The wood of Ehretia serrata Roxb. is very hard and is used as tool-handles. Cordia sebestena Linn, is cultivated in gardens for the large orange-red flowers. Many species of Myosotis and Cynoglossum are also cultivated in gardens in the cold countries.
The family is divided into 5 subfamilies as noted below:
I. Style terminal; fruit a drupe.
Subfam. 1. Cordioideae: Style 4-fid; drupe 4-celled.
Subfam. 2. Ehretioideae: Style bifid or styles 2; drupe 2-seeded or of four 1-seeded pyrenes.
Subfam. 3. Heliotropioideae: Style simple or bifid; a ring of hairs present below stigma, fruit drupe or nutlets.
II. Style gynobasic; fruit of 4 nutlets.
Subfam. 4. Boraginoideae: Corolla with scales inside or not, often bent or zygomorphic; nutlets 4 or less.
Subfam. 5. Wellstedloideae: Flowers 4-mcrous; ovary 2-celled with 1 ovule in each cell.
The family is closely allied to Polemoniaceae and Hydrophyllaceae. It is also related to Solanaceae and Nolanaceae on one side and to Convolvulaceae on the other. Hutchinson’ splitted Boraginaceae into Boraginacea and Ehretiaceae and these 2 families are placed- wide apart.
Boraginaceae is placed by him in a monotypic order Boraginales which is placed between Polemoniales and Lamiales. Ehretiaceae is included by him in his Verbenales. This treatment of the family by Hutchinson has not been supported by subsequent botanists.
Family # 3. Verbenaceae:
Verbenaceae are herbs, shrubs or trees, usually with square stem. Leaves are opposite or whorled, simple or pinnately or palmately compound, exstipulate. Inflorescence cymose or racemose, often paniculate, or a dense spicate head, usually bracteate. Flowers usually zygomorphic, bisexual, rarely polygamous.
Calyx of 5 united sepals, tubular or bell- shaped, persistent; teeth or lobes valvate, often more than 5. Corolla of 5 united petals, bilabiate or bell-shaped and oblique with spreading limb; lobes imbricate.
Stamens 4, epipetalous, didynamous, often only 2, rarely 5; staminodes often present in diandrous flowers; filaments free, usually pairs unequal in length; anthers 2-celled, opening lengthwise; often an inconspicuous disc is present.
Carpels 2, syncarpous in a superior 2celled or 4-celled or rarely 1-celled ovary; ovules 1 or 2 in each cell with downwardly directed micropyle; style terminal; stigma 2-lobed or entire. Fruit usually drupaceous, 1-4-seeded, often enclosed in the persistent calyx. Seed usually without endosperm; embryo straight.
The plants vary in habit from small trailing herb like Phyla nodiflora (L.) Green to lofty trees like Tectona grandis L. f. and Gmelina arborea Roxb. Petrea volubilis Linn, is a climber or a scandent shrub. Avicennia a genus of trees in mangrove forests develop pneumatophores and have fruits that germinate viviparously.
Several species of Clerodendrum are myrmecophilous, e.g. C. fistulosum Becc. that shelter ants in the hollow internodes. Leaves are usually simple but compound leaves are found in Vitex. The leaves of Verbena is often very finely sected.
Inflorescence is racemose or cymose. In Lippia, Stachytarpheta it is a spike, dense cylindrical head in the former and long and slender in the latter.
Pendulous spike occurs in Citharexylum, Petrea, etc. and in some Verbena. Dichasial cyme is found in most Clerodendrum while in C.fragrans Vent it is compact and corymbose. Unisexual flowers are found in Aegiphila, actinomorphic in Callicarpa and tetramerous in Physopsis, Callicarpa, etc.
In Symphorema and Sphenodesma the bracts form an involucre and are macrescent in the former genus persisting in the fruit. In Holmskioldia the calyx is petaloid. Stamens 5 in Genusia and Sphenodesma, 5-6 in Tectona while in Symphorema 6-16. Corolla lobes in Symphorema are 6-16. Carpels are 4 in Duranta and 5 in Genusia.
In Lantana and Lippia ovary is unilocular, one of the 2 carpels being abortive. Drupes usually separating into pyrenes but undivided in Gmelina, Premna, etc. Fruits are dry and capsular in Caryopteris, Avicennia, etc. while in Verbena there are 4 nutlets. In Chloanthes and Stilbe endosperm is present in the seed.
The floral formula of the family is expressed as:
The family consists of over 2500 species in about 100 genera and is distributed in the tropical and subtropical regions. In India 165 species occur in the plains while a few are cultivated in the hills.
Phyla nodiflora (L.) Green, Lippia geminata H. B. & K., many species of Clerodendrum, Stachytarpheta indica Vahl., Callicarpa macrophylla Vahl., Gmelina arborea Roxb., Tectona grandis L. f. are common in the plains. Lantana aculeata Linn, a bushy shrub is a pest in waste places. Duranta repens Linn, indigenous to Tropical America has been naturalised in this country and is a common hedge plant.
Phryma leptostachya climbs to an elevation of 2000 mtrs. in the West Himalayas and Caiyopteris wallichiana is found in the outer Himalayas upto an elevation of 1500 mtrs. (According to Airy Shaw Nyctanthes arbor-tristis Linn.-Shephalika belongs to this family.)
Characteristic anatomical feature is simple perforations in the vessels, rarely scalariform or reticulate. Intervascular pitting is small to moderately large and wood parenchyma is paratracheal. Fibres are usually septate. In Lantana the xylem is forked.
In Avicennia successive rings of bundles are found. In many genera cork development is superficial. The family includes a few plants economically very important. Tectona grandis is the famous Teak tree the timber of which is much valued for manufacture of furniture, as building material and so many other things.
Gmelina arborea is another good timber tree. Vitex negeundo Linn, is a febrifuge and V. peduncularis is effective in Kalazar or Black fever Clerodendrum indicum (L.) O. Ktz. (Syn. C. siphonanthus R. Br.) is also said to have medicinal value Clerodendrum fragrans is often cultivated for beautiful flowers in a compact inflorescence. Sp. of Verbena is cultivated in the plains as well as in the hills. Bark of Avicennia is used in tanning. Premna barbata and P. latifolia of the outer Himalayas have the wood very hard and are useful in different ways. They yield good fuel and can be ignited by friction.
The family is divided by Briquet into 7 tribes as noted below:
A. Inflorescence an elongated or head-like spike or raceme or uniparous cyme.
Tribe 1. Stilbeae:
Seed with endosperm, flower actinomorphic or slightly zygomorphic. Stilbe, Campylostachys, etc.
Tribe 2. Verbeneae:
Seed without endosperm, flower more or less actinomorphic. Verbena, Lantana, Phyla, etc.
B. Inflorescence cymose paniculate or umbellate, rarely flowers solitary.
Tribe 3. Chloantheae:
Seed with endosperm, fruit a drupe, ovule marginal. Chloanthus, Acharitea, etc.
Tribe 4. Viliceae:
Seed without endosperm, fruit a drupe, ovule marginal. Tectona, Callicarpa, etc.
Tribe 5. Caryopterieae:
Seed without endosperm, fruit capsular. Caryopteris, etc.
Tribe 6. Symphoremeae:
Seed without endosperm, fruit dry, ovule pendulous. Congea, Symphorema, etc.
Tribe 7. Avicenneae:
Seed without endosperm, fruit capsular, placenta central. Avicennia. The tribe Avicenneae is now placed by some in a distinct family Avicenniaceae. The family is closely allied to Labiatae and to Boraginaceae and Scrophulariaceae to some extent.
According to Hutchinson Verbenaceae and Labiatae are not at all related and Verbenaceae terminates the woody line Lignosae while Labiatae (Lamiaceae) is at the end of Herbaceae. Hutchinson’s view as regards the position of these 2 families in the system of classification has not been accepted by subsequent workers.
Family # 4. Labiatae (Lamiaceae):
Labiatae are annual or perennial aromatic herbs or shrubs with quadrangular stem. Leaves are simple, entire or variously lobed or sected, opposite or whorled, exstipulate. Floral whorls or verticillasters are double unipared cymes situated in axils of foliage leaves, or where the subtending leaves are bract-like forming, terminal spikes or racemes, often panicled; bracteoles usually present.
Flowers are hermaphrodite, strongly zygomorphic, usually bilabiate, hypogynous. Calyx gamosepalous, persistent, tubular or campanulate or ovoid, bilabiate or 5- or more-toothed. Corolla usually bilabiate, 5 or rarely 4 lobed, imbricate; tube often annulate inside.
Stamens 4, didynamous, the 2 pairs usually inserted at different levels in the corolla-tube; rarely stamens only 2; the anther- cells often separated from one another by transverse connective and placed at an angle with each other; disc prominent, sometimes lobed, uniform or produced in front.
Ovary of 2 carpels, syncarpous, superior, originally 2-celled, divided into 4 loculi by false partition, ovary deeply 4-partite with gynobasic style and bifid stigma; ovule 1 in each cell, erect, orthotropous, beaked and with inferior micropyle. Fruit of 4 nut lets with basal or lateral areola, endosperm absent or very scanty and fleshy.
Majority are herbs, undershrub’s or shrubs, while Leucosceptrum canum Smith is a short tree; some species of Hyptis also attain tree size. Species of Colquhounia are often scandent or rambler. Ajuga lobata D. Don. is a stoloniferous herb with prostrate or creeping stem.
Leucas biflora R, Br. has long procumbent branches. Leaves are whorled in Plectrantheef ternifolius D. Don (Rabdosia ternifolia), Leucas temifolia Desf. etc. and fascicled in Leucas rosamarinifolia Bth.. Pinnately compound leaves are found in Salvia hydrangea DC. and S. plectranthoicles Griffith, trifoliate in Rtibileucris palmala Kudo, finely seeted in Dracocephalum tanguticum Maxim, and more or less lyrate in Eremostachys.
The terminal spikes are often very dense and head-like. In Notochaetc hamosa Benth. the axillary inflorescence is a globose head. Globose head-like inflorescence also occur in some Hyptis. Calyx 2-lipped in many genera with unequal teeth or tubular with the teeth equal in others. In Scutellaria the upper lip with a pouch or shield-like protuberance.
In Otostegia the calyx limb is very much expanded at the mouth. Corolla, almost always bilabiate but in Teucrium there is no upper lip, the limb is slit behind to form a 5-lobed lower lip. In Coleus the stamens are monadelphous, the filaments connate below in a sheath separate from the corolla.
Perfect stamens only 2 in Salvia-, the connective linear, transverse with an upper arm having one fertile anthercell and a lower arm with or without any anthercell. In Leucosceptrum the anther is unilocular and reniform.
In Lycopus, Perowskia, giziphora etc. there are only 2 perfect stamens. Nutlets with a thick and more or less fleshy pericarp in Gomphostemma. In Ajuga, Cymaria, Leucosceptrum and a few other genera the areola of the nutlets are lateral.
The family Labiatae is mainly distributed in the temperate regions and consists of about 200 genera and 3000 species. About 350 species are found in India in the Himalayas and in the hills of Assam and Peninsular India.
Quite a good number are also common in the plains, e.g. Ocimum sanctum Linn., Salvia plebeja R. Br.; Leonurus sitfiricus Linn., Leucas lauandulaefolia Nees, Anisomeles indica (L.) O. Ktz., Leonotis nepetifolia R. Br. Pogostemon plectranthoides Dcsf., Leucas cephalotes Spr. etc.
Leucosceptrum canum Sm., mafty species oiNepeta, Salvia, Thymus serpyllum Linn., Mentha arvensis Linn., M, sylvestris Linn., Royllea calycina Briq., a few species of Phlomis, -Dracocephalum, Stachys, Scutellaria, etc. are Himalayah.
Vessels occur in multiples in many vascular bundles., very small in dimension, usually with spiral thickenings and are semi-ringporous; perforations are simple and intervascular pitting is alternate.
Wood parenchyma is poorly developed and paratracheal. Fibres are simple-pitted and sometimes septate. In pericycle schlerenchyma fibres are few in’isolated strands. Endodermis is often indistinct.
Many species contain volatile oil. Lavandula vera DC. is the source of lavender oil. Oil of rosemary is obtained from Rosmarinus officinalis Linn. Thymus vulgaris Linn, yields thymol, while menthol is obtained from Mentha piperata Linn.
Mentha viridis Linn, is Pudina, much used to flavour curries and chutney. Mentha cablin Bth. gives patchouli oil and Pogostemon Heyneanus Benth. the Indian Patchouli is a substitute. The root-tubers of Stachys palustris, some species of Coleus and Ocimum are edible.
Ocimum Kilimandscharicum Gurke is the camphor basil, from the oil of which camphor is manufactured. Seeds of Ocimum americanum Linn. 0. basilicum Linn, and Lallemantia Royleana Benth. become mucilagenous when wetted and a poultice of the same is applied to abscesses and boils.
The juice of the leaves of Ocimum sanctum Linn, is used in catarrhal affections of children. Leucas cephalotes Spr. is also reputed to have medicinal properties.
The family has been divided into 8 subfamilies by Briquet as noted below:
A. Style not gynobasic; nutlets with lateral areola.
Subfam. I. Ajugoideae:
Endosperm absent—Teucrium, Ajuga, Rosmarinus, etc.
Subfam. II. Prostantheroideae:
Endosperm present—Proslanthera, Wrixonia, etc.
B. Style gynobasic, nutlets with basal areola.
Subfam. III. Prasioideae:
Nutlets drupe like with somewhat fleshy pericarp— Gomphostemma, Prasium, etc.
Subfam. IV. Scutellarioideae:
Nutlets dry, seeds transverse—Salazaria, Scutellaria, etc.
Subfam. V. Lavanduloideae:
Nutlets dry, seeds erect, anthers ultimately unilocular, radicle superior—Lavandula.
Subfam. VI. Stachydoideae:
Nullets dry, seeds erect, stamens on the upper lip, radicle inferior—Stachys, Salvia, Mentha, etc.
Subfam. VII. Ocimoideae:
Nutlets dry, seeds erect, anther cells confluent, stamens declinate, radicle inferior—Ocimum, Hyptis, Geniosporum, etc.
Subfam. VIII. Catopherioideae:
Nutlets dry, seeds erect, radicle curved lying against the cotyledons—Catopheria.
Labiatae is closely allied to Verbenaceae and the 2 families are placed side by side in different systems of classification.
Hutchinson however places Labiatae (Lamiaceae) in Lamiales which is according to him most highly evolved order among the Dicotyledonae and terminates the line of Herbaceae while Verbenaceae is in Verbenales an order terminating the woody line Lignosae. So according to Hutchinson Verbenaceae and Labiatae are not allied to each other.
Family # 5. Solanaceae:
Solanaceae are herbs or shrubs, rarely small trees or climbers; the juice is often poisonous. Leaves are simple, alternate, exstipulate, often lobed. Inflorescence a cyme or cymose panicle, often helicoid cyme, terminal or axillary or lateral or extra-axillary, often solitary or in clusters; bracts and bracteoles absent.
Flowers are actinomorphic or zygomorphic, bisexual, hypogynous, with a flat thalamus. Calyx gamosepalous, usually 5-lobed, persistent and enlarging in fruit. Corolla gamopetalous, rotate or funnel- or bell-shaped, rarely bilabiate, plicate-imbricate or plicate-convolute.
Stamens 5, epipetalous, alternating with corolla-lobes, sometimes 4 and often didynamous; anthers 2-celled or 1-celled, often connivent, dehiscing longitudinally or by apical pores; connective often prolonged; a hypogynous disc usually present.
Carpels 2, syncarpous in an obliquely placed superior ovary, 2-celled or 3-5-celled due to false partitions; ovules anatropous,’ numerous on thick axile placentas; style terminal, simple; stigma capitate or bilobed. Fruit a capsule or a berry, often enclosed within the enlarged calyx. Seeds compressed, discoid or reniform, with fleshy and translucent endosperm and straight or curved embryo.
The leaf arrangement is peculiar in some species. The leaves are in pairs of which one is larger than the others. Often both the leaves of a pair are raised to a higher position or only one is raised and the other remains in original place. In the former case they appear to be the leaves of the axillary branches which terminate in a flower.
In the other case the larger leaf of the pair has a branch in the axil and is raised to a higher position in the axillary shoot, while the smaller leaf without any axillary vegetative bud remains in its place. So that a pair of leaves at each node contains leaves belonging to two successive shoots of a sympodial stem.
The family predominantly of herbaceous or shrubby plains includes a few trees and some lianas. Solarium jasminoides Paxt and S. Wendlandii Hook.f. are climbers while species of Dunalia and Cyphonandra are short trees. Solarium tuberosum Linn, and a few other species have stem-tubers. S. tuberosum and S. jasmininoides have pinnate leaves.
Flowers are actinomorphic but may be termed zygomorphic due to the obliquely placed ovary. Corolla is regular but in Hyoscyamus and Schizanthut it is bilabiate. Salpiglosis also has strong zygomorphic flowers. Calyx is persistent and accrescent.
In Physalis it becomes dry and papery and encloses the berry completely. It is scarlet in P. alkekengi Linn, the “Chinese lantern.” In Datura the long limb of the tubular calyx falls off leaving a disc-like basal portion that enlarges in fruit.
The corolla in Brunfelsia changes colour and in B. latifolia Benth. the corolla is violet in the beginning then turns white and from white changes to yellow. For this reason the plant is called popularly as the “Yesterday—Today and Tomorrow” —plant. Fertile stamens only 2 in Schizanthus.
The anthers in Solarium fuse together in a cone over the style and the dehiscence is by apical pore, in other genera they are distinct and dehisce by longitudinal slits. In Browalia the anther is 1-celled. Cyphonandra has an enlarged connective. Ovary unilocular in Henoonia, while in Capsicum it is 2-locular below but 1-locular in upper part.
The floral formula is expressed as:
Stem anatomy shows that intraxylary phloem is invariably present. The fibres occur as isolated groups or as a -continuous ring. Fibres in pericycle are in strands or in loose ring with or without stone cells. Vessels may be in irregular clusters, in numerous or radial multiples, etc. Perforations are simple and intervascular pitting is alternate.
The family with over 2000 species in 90 genera is found in the tropical and subtropical regions in both hemispheres but more in Central and S. America. About 60 species are found wild in India in the plains and a few in the hills besides a few exotics.
Solanum has several species of which S. tuberosum Linn, the potato-plant was introduced and extensively cultivated. S. melongenaL. is also cultivated for the fruit. S. trilobatum Linn, is a halophyte occurring in littoral forests in India.
Datura metel Linn, is wild in the plains and D. stramonium Linn, occurs in subtropical parts of the Himalayas. Cestrum noctumum Murr. is cultivated in gardens for fragrant flowers while a few other species of the genus, all from Trop. America have been naturalised and grow wild in India.
Many important economic plants belong to this family. Solanum tuberosum Linn. is the potato-plant and Lycopersicon lycopersicum Karst. is the tomato. Solanum melongena Linn, is the egg-fruit plant or Brinjal plant the fruits of which are much used as vegetable in tropical Asiatic countries.
Cyphonandra betacea (Cav.). Sendt. of Peru has fruits that taste like tomato and is called the Tree-tomato. Physalis peruviana Linn, is the Cape gooseberry cultivated for its acid-sweet edible berries. Capsicum frutescens Linn, is the green pepper used as a condiment.
Nicotiana tabacum Linn, is the Virginian Tobacco and N. rustica Linn.—Central Asain Tobacco. Atropa belladona Linn, gives atropin used to dilate the pupil. Hyoscyamus niger Linn, has the same property and also medicinally used in other ways.
Datura stramonium Linn., Withania somnifera Dun., Solanum surattense Burm. f. are poisonous and have medicinal properties. Mandragora officinarum Linn, the Mandrake, is a medicinal plant and is notorious for its so called magic properties.
Petunia is a genus of herbs several species of which are cultivated in gardens for the large showy flowers. Species of Browalia, Cestrum, Datura, Solanum, Brunfelsia etc., are also cultivated either for the beauty or the fragrance of the flowers.
Wettstein divided the family into 5 tribes:
Group A:
Embryo strongly curved forming a semicircle; fertile stamens 5, filaments equal.
Tribe I. Nicandreae:
Ovary 3-4-chambered; the wall of the ovary dividing the placentas irregularly.
Tribe II. Solaneae:
Ovary 2-chambered.
Tribe III. Datureae:
Ovary 4-chambered; the wall of the ovary equally dividing the placentas.
Group B:
Embryo slightly curved or not.
Tribe IV. Cestreae:
Fertile stemens 5; seeds small, not compressed.
Tribe V. Salpiglossideae:
Fertile stamens 2-4; flowers zygomorphic. According to some workers Solanaceae is closely allied to Convolvalaceae both having 5-merous flowers, actinomorphic corolla, persistent calyx, usually bicarpellary 2-ceBed ovary, etc. Convolvulaceae is a family of predominantly climbers or twiners while plants of Solanaceae are predominantly erect.
The obliquely placed ovary in Solanaceae is a very distinct character that separates it from Convolvulaceae and other allied families.
Solanaceae is also very close to Scrophulariareae so much so that a plant of Solanaceae with irregular flower can be distinguished from Scrophulariaceae only by the position of the ovary. Flowers of Solanaceae are usually regular while in Scrophulariacea they are usually irregular.
In Solanaceae stamens are usually 5 in number while in Scrophulariaceae they are usually 4 and didynamous. Solanaceae is also considered to be allied to Boraginaceae and Polemoniaceae.
Engler included all these families in the order Tubiflorae recognising the close affinity between them but Rendle takes out Convolvulaceae from Tubiflorae. So according to Rendle Convolvulaceae is not closely allied to Solanaceae as are the other families.
Hutchinson placed Solanaceae and Convolvulaceae in Solanales while Scrophulariaceae in Personates which however is placed next to Solanales. So according to him Solanaceae is closer to Convolvulaceae than to Scrophulariaceae. But Takhtajan considers Solanaceae is closer to Scrophulariaceae than to Convolvulaceae.
Hutchinson has raised the tribe Salpiglossideae to the rank of distinct family and named it as Salpiglossidaceae. The tribe was included by some under Scrophulariaceae, the flowers being zygomorphic. Hutchinson’s treatment has not been supported by later workers.
Recently D’Arcy made critical taxonomic studies of the family Solanaceae and merged Nolanaceae under Solanaceae. According to him Solanaceae should be divided into 3 sub-families viz. Solanoideae, Cestroideae and Nolanoideae.
Family # 6. Scrophulariaceae:
Scrophulariaceae are herbs or undershrub’s, sometimes twining or trailing, rarely parasitic. Leaves are usually simple, alternate or opposite of whorled, exstipulate. Inflorescence is a raceme or spike or cymose, rarely flowers solitary.
Flowers are bisexual, zygomorphic, hypogynous, bracteate, Calyx gamosepalous, 4-5-partite, with imbricate or valvate lobes. Corolla gamopetalous, with 5 lobes, personate or rotate or bilabiate, often sptirred or saccate; lobes imbricate; rarely corolla regular.
Stamens usually 4, didynamous, sometimes 5, rarely only 2, epipetalous; anthers 2-celled, one cell larger than the other, often 2-celled at the initial stage and later 1-celled. A hypogynous annular or unilateral or lobed disc is present.
Carpels 2 in a syncarpous, superior, 2-celled rarely 4-celled medianly placed ovary; ovules numerous on thick axile placenta, anatropus or am- phitropous; style simple terminal; stigma entire or bilobed. Fruit a capsule or a berry; seed with endosperm and a straight or slightly curved embryo.
Herbaceous plants predominate in this family with few shrubs, e.g., Scrophularia, Verbascum, etc., species of Rhodochiton and Maurandia are climbers, climbing by means of sensitive petioles. Paulownia* is a tree while Harveya and Hyobanche are total parasites.
Some species of Pedicularis, Striga, Sopubia are root-parasites. Melamporum and Castilleja are saprophytes. Some species of Limnophila and Aubulia are heterophyllous. The leaves of Verbascum are decurrent and give the stem a winged appearance.
The family shows a wide range of variation as regards flower-structure. Flowers are solitary in Bacopa, Kickxia, etc., but usually in racemosc or cymose inflorescence in other genera. In Verbascum repeated dischasia are formed.
In Antirrhinum the terminal flower is different from the rest. Castilleja has brightly coloured bracts. Flowers are usually zygomorphic but Scoparia, Bacopa and Verbascum have flowers which are regular or almost so.
Calyx is 5-lobed but 4 in Euphrasia where the posterior sepal is supressed, and in Calceolaria where the 2 posterior sepals are united. Limbs of corolla are spreading as in Veronica while the 2 lips of corolla in Linaria and Antirrhinum’ touch each other so that the mouth of the corolla is closed.
In Linaria and Diascia the corolla is spurred. In Digitalis corolla is bell-shaped- In Scoparia, Verbascum, Bacopa, etc., the lobes of corrolla are similar and equal or subequal so that corolla in these genera are regular.
In Verbascum and Capraria there are 5 fertile stamens. Scrophularia and Pents lemon have 4 fertile stamens and 1 staminode. Castilleja, Linaria and most other genera have 4 fertile stamens, Stemotria has 3 and Calceolaria, Hebe and Veronica have 2 only. In the genus Lindernia some species have 4 fertile stamens while others have 2 and 2 staminodes.
In Euphrasia the anther is appendaged and the pollens are loose and powdery. Carpels are mostly 2 and equal but in Antirrhinum the anterior carpel is larger. Capsules are septicidal or loculicidal while in a few genera the dehiscence is by apical pores. Fruits of Halleria and Leucocarpus are berries.
The floral formula for the family is:
The pericycle is present as a continuous ring of fibres which often occur as isolated strands, or these may De absent. Vessels are narrow and variously arranged. Wood parenchyma is absent or poor and paratracheal or apotracheal. Fibres are thin walled and with simple pits. Internal phloem is absent in this family. Endosperm haustoria is always present.
The family consists of over 3000 species under 220 genera occurring mainly in northern and southern temperate regions. A few are saprophytes and some are aquatics.
The aquatics are usually heterophyllous, the submerged leaves being finely sected and those above water with entire lamina. In India 275 species are found in the hills as well as in the plains. Lindernia indica O.Ktz. usually grows on old walls and rubbish heaps. Scoparia dulcis Linn, with white regular flowers is a weed of waste places.
Kickxia ramosissima (Wall.) Janch., Bacopa monniere Pennel, Mazusjaponicus O.Ktz., Lindernia brachiata Link & Otto., Limnophila heterophylla Bth. etc. are other weeds common in the plains.
Pedicularis a large genus of about 500 species, is well represented in the Himalayas at high altitude. Hemiophragma heterophylla Linn, a prostrate herb is very common in temperate belt of the hills. Torenia cordata (Griff. ) Dutta is a medicinal plant of the E. Himalaya. Digitalis purpurea Linn, an introduced plant is commonly cultivated in Indian hill stations for the large purple flowers.
The family is not of much importance economically but includes a few medicinal plants. Digitalis purpurea Linn, yields from the leaves digitalin a heart stimulant. Bacopa monnieri Pennel is considered by some as the “Brahmi” of the Indian Vaids. Kickxia ramosissima is useful in diabetes and species of Scrophularia were formerly used to cure scrofula.
Wettstein divides the family into 3 subfamilies as mentioned below:
Group A.
Two lateral lobes of corolla covered by two posterior lobes.
Subfam. 1. Pseudosolanioideae:
Leaves alternate, stamens 5.
Subfam. 2. Anlirrhinioidear:
Leaves opposite (at least the lower), stamens 4.
Group B.
Two lateral lobes of corolla not covered by posterior lobes.
Subfam. 3. Rhinanthoideae:
Stamens 4 or 2.
Scrophulariaceae is closely allied to Labiatae and Acanthaceae, being predominantly herbaceous, flowers usually zygomorphic, stamens usually 4 and didynamous, and fruit usually dry.
It is also very close to Solanaceae and Convolvulaceae, having exstipulate leaves, persistent gamosepalous calyx, bicarpellary superior ovary, etc. A plant of Solanaceae with irregular flower resembles much like a Scrophulariaceae while some Scrophulariaceae with regular flowers resemble plant of Solanaceae or Convolvulaceae.
Intraxylary phloem present in Solanaceae and Convolvulaceae is however absent in Scrophulariaceae. Scrophulariaceae is also related to Bignoniaceae having zygomorphic flowers, exstipulate leaves, usually 4 didynamous stamens, presence of hypogynous disc and superior bicarpellary ovary.
The genus Paulownia seems to be the connecting link between the two families. Bignoniaceae however is a predominantly woody family with compound leaves, and seeds without endosperm.
Family # 7. Bignoniaceae:
Bignoniaceae are woody plants, trees, shrubs or climbers. Leaves are opposite, pinnately compound, exstipulate; trees often have very large leaves. Inflorescence a dichasial cyme or helicoid or paniculate, often racemose, or rarely clustered on the old branches or stem.
Flowers are zygomorphic bisexual, hypogynous, usually large and showy. Calyx gamosepalous, 5-lobed or toothed or 2-lipped; lobes imbricate or valvate. Corolla gamopetalous, funnel-shaped or campanulate and oblique or sometimes bilabiate; lobes imbricate.
Stamens 4, didynamous, inserted on the basal part of the corolla tube; anthers bilobed, lobes divaricate or one placed at a little higher level than the other; a fifth posterior stamen is rarely represented as astaminode. Disc fleshy, annular, hypogynous.
Carpels 2; ovary syncarpous, superior, bilocular or rarely unilocular; ovules anatropous, numerous on axile or parietal placenta; micropyle of ovules directed downward; style simple, filiform; stigma 2-lobed. Fruit a septicidal or loculicidal bivalved capsule or sometimes indehiscent. Seeds without endosperm, usually winged or comose.
The family includes some large trees like Stereospermum, Spathodea, Kigelia, etc., but a few are dwarf xerophytes found in Brazil. The climbers usually have the terminal leaflet transformed into tendril while Campsis radicans (L.) Seem, is a root climber.
Leaves are usually pinnate but tripinnate leaves are found in Oroxylon, Millingtonia, etc., and bipinnate leaves in Jacaranda while digitate leaves are found in Tabebuia.
Simple leaves rarely occur as in Crescentia. In the case of climbers where the terminal leaflets are metamorphosed into tendrils there is only one pair of leaflets remaining in a leaf. Kigelia has a long pendulous racemose inflorescence, while in Pajanelia it is a thyrsoid panicle.
In Crescentia flowers are solitary or in small clusters. Fertile stamens are usually 4 but Oroxylon has 5 fertile stamens and Catalpa has only 2. Ovary is bilocular but in Kigelia, Eccremocarpus and Crescentia it is unilocular with parietal placentation while the placentation is axile in other cases.
Crescentia, Kigelia and Parmentiera have indehiscent fruits while others have bivalved capsule and the capsule of Eccremocarpus splits from base to apex while the seeds remain attached to the septa.
Fruits of Oxoxylon indicum Vent. is about a metre, or more long, flat and 5-7 cm. broad. Those of Crescentia cujete is round and as big as a human head. Seeds are winged but those of Crescentia, Kigelia, etc., are wingless. The seeds of Bignonia have very fine markings on the wing.
Floral formula for the family is represented as:
Anomalous secondary thickening in the stems of climbing species is a characteristic feature; the thickening is not uniform and formation of secondary xylem and phloem varies greatly at different parts in the stem so that steler cylinder develops ridges and furrows.
Vessels are irregularly disposed with simple perforations and alternate intravascular pitting. There is paratracheal wood parenchyma and the pericycle is usually composed of fibrous strands. Fibres are septate in twining plants.
Bignoniaceae with about 650 species under 120 genera is found in the tropical countries of the world but chiefly in S. America. It is represented, in India by several tree-genera e.g., Stereospermum, Oroxylon, Heterophragma, Dolichondrone, etc., which are indigenous, but the family is better known in this country for the introduced trees, climbers and shrubs having large showy flowers.
Bignoniaceae is closely allied to Scrophulariaceae which however is a predominantly herbaceous family. Didynamous stamens, bi-carpellary superior ovary, presence of hypogynous disc, zygomorphic flowers and usualy capsular fruits are characters common to both. It is also allied to Acanthaceae and Pedaliaceae.
Hutchinson however placing more importance on the woody habit places Bignoniales with Cobaeaceae, Bignoniaceae, Pedaliaceae and Martyniaceae near the end of his Lignosae far removed from his Personales of Herbaceae where Serophulariaceae, Acanthaceae, etc., are included Hutchinson’s arrangement of these families has not been followed by subsequent workers.
The family has been divided into 4 tribes, e.g.:
I. Bignonieae:
Ovary bilocular cylindric or compressed, parallel to the septum; capsule septicidal; seeds winged. —Bignonia, Pyrostegia, Oroxylon, Millingtonia, etc.
II. Tecomeae:
Ovary bilocular, cylindric or compressed, at right angles to the septum; capsule loculicidal; seeds winged. —Tecoma, Pajanelia, Spathodea, Catalpa, Heterophragma, etc.
III. Eccremocarpeae:
Ovary unilocular; capsule dehiscing from base to apex; seeds winged.—Eccremocarpus.
IV. Crescentieae:
Ovary uni- or bilocular; berry or dry and indehiscent fruit; seeds not winged. —Kigelia, Crescentia, etc. Bignoniaceae gains importance for many species having showy flowers.
Among these Stereospermum suaveolens DC. and St. personatum (Hassk.) Chatterjee are the Parul trees or Patala of Sanskrit literature. Millingtonia hortensis Linn. f. with long, white, fragrant flowers is the Akas-nim, met with in parks and gardens and on roadsides as an avenue trees.
These are indigenous to India. But quite a number of foreign species are very often seen in Indian gardens and a list of the most common ones is given here. These are all tropical plants and are cultivated in the plains.
Spathodea campanulata Beauv.—Central Africa, tall tree with large crimson flower.
Jacaranda ovalifolia R. Br. — Brazil; small tree with purplish blue flowers.
J. filicifolia D, Don.— same, leaflets smaller.
Tabebuia rosea DC.—Trop. America, small tree with pink flower.
T. chrysantha Nichols—same with yellow flowers.
T. donnell-smithii Rose—same.
Catalpa ovata Don.—W. China, small tree with yellow flowers.
Pyrostegia veruista (K.G.) Miers.—Brazil, twining shrub with orange flowers.
Bignonia capreolata Linn.—Argentina, twining shrub with reddish yellow flowers.
Clyptosloma callistegioides (Cham.) Bur.— Syn. B. speciosa R. Grah. Trop. Am. twiner, flowers with yellow tube and pink limb.
Saritaea magnifica (Sprague) Dug. (known to the gardeners as Bignonia magnifica)— Colombia; twiner with mauve flowers,
Campsis radicans (L.) Seems—N. Am. root climber; fls. orange-red
Tecomnria capensis (Th.) Spach.—S. Africa; rambling shrub, fls. flame-coloured.
Tecoma starts (L.) H.B.K.—Trop. Am. tall shrub, fls. golden yellow.
Family # 8. Orobanchaceae:
Orobanchaceae are annual or perennial herbs, root parasites with very little or no chlorophyll; stem short, usually simple with scale-like alternate leaves. Inflorescence a simple spike or panicle, or flowers solitary at the axil of bracts.
Flowers are hermaphrodite, medianly zygomorphic and hypogynous. Bracts and bracteoles scale-like; bracteoles 2 or 1, often absent. Calyx gamosepalous, 2-5 lobed, tubular or spathe-like, persistent; lobes valvate or open in bud.
Corolla gamopetalous, bilabiate or 5 lobed; tube curved, usually villous at the throat; lobes imbricate. Stamens 4, didynamous, epipetalous, inserted below the middle of the corolla tube; anthers 1- or 2-celled, one cell often abortive, cells frequently spurred at the base; dehiscence by slits or by apical pores.
A glandular or unilateral disc usually present. Carpels 2, rarely 3; ovary syncarpous, superior, 1 or 2 celled, with numerous anatropous ovules on parietal placentas which are often confluent; style short; stigma peltate. Fruit a capsule, 1-celled or perfectly or imperfectly 2-celled. Seeds minute, with a pitted, tubercled or reticulated testa; endosperm oily or fleshy; embryo undifferentiated.
The plants derive their nourishment from the host plant by means of exogenous haustoria that enters into the root of the host by enzyme action. Where haustoria is absent a contact between the vascular bundles of the host and the parasite is established and the nutrient material passes from the host to the parasite.
Floral formula:
K (2 – 5) C (6) A (4) G (2)
This is a comparatively small family with about 140 species under 12 genera found mainly in the temperate and subtropical parts of the Old World, the largest genus Orobanche with about 100 species extends also to the tropical region. In India the family is represented by a few species of Orobanche, Aeginetia, Christisonia, etc.
Orobanchaceae is closely allied to Scrophulariaceae in which family a few genera are also root parasites. The floral construction in both the families are more or less similar and in this respect it is also allied to Gesneriaceae. The 3 families are considered to be closely associated to each other by almost all workers on taxonomy.
Family # 9. Pedaliaceae:
Pedaliaceae are annual or perennial herbs, rarely shrubs, usually viscid. Leaves are simple opposite, or the upper alternate, exstipulate; the lower leaves very rarely trifoliate; hydathodes usually present. Inflorescence a dichasial cyme, axillary, rarely flowers solitary.
Flowers are bisexual, zygomorphic, hypogynous. Calyx gamosepalous, tubular, or campanulate, or spathe like, persistent, hairy; lobes 5, imbricate. Corolla gamopetalous, indistinctly bilabiate and ventricose; lobes 5, imbricate. Stamens 4, epipetalous, didynamous; a short staminode is often present; anthers bilocular, introrose, dehiscing longitudinally.
Carpels 2, syncarpous, forming a superior uni- or bilocular or quadrilocular ovary due to development of false septa; ovules 1 —∞ in each locule on axile or parietal placenta, anatropous; style long and filiform, persistent; stigmas 2, leafy, elliptic. Fruit a capsule or a nut with smooth or hairy pericarp, often with hooked or spiny outgrowths. Seed with a straight embryo and scanty endosperm.
The usual floral formula is:
K (5) C (5) A (4) G (3).
Species of the genus Trapella are aquatic herbs having dimorphic leaves, and flowers with 2 stamens and inferior ovary. Martynia has 2 fertile stamens and 3 staminodes.
Pedaliaceae is a small family comprising about 60 species only under 17 genera, occurring in S. Africa, Indo-Malayan region and Australia. They are found mare in the arid region and on sea shores. Martynia annua Linn, native of Mexico grows wild in the plains of India and Sesamum indicum Linn, is widely cultivated.
The family is closely allied to the other families of Tubiflorae and particularly to Acanthaceae. Many authors prefer to segregate 3 genera, viz., Probscidia, Craniotia and Martynia under a distinct family Martymaceae mainly on parietal placentation. The family includes Sesamum indicum Linn, a very important oil yielding plant. Oil is also extracted from S. angustifolium Engl, and Pedalium murex Linn.
Family # 10. Lentibulariaceae:
Lentibulariaceae are insectivorous herbs, often aquatic or marsh-plants, and often rootless. Leaves are in submerged plants multifid with capillary segments bearing bladders; small and rosulate in terrestrials and obsolete in the epiphytes.
Flowers are hermaphrodite and strongly zygomorphic, borne on racemes or spikes; bract and bracteoles small or absent; in case of submerged plants the raceme projects above water surface and are often provided with inflated modified leaves serving as floats. Calyx persistent, 2-lipped or 2-5-lobed or partite.
Corolla bilabiate, the upper lip smaller, entire or emarginate, the lower much larger, 3-5 lobed and saccate or spurred. Stamens 2, attached to the base of the corqjla, filaments broad and curved, anthers 2-celled, cells transversely confluent and in some cases ultimately becoming 1-celled; anthers dorsifixed and dehiscing longitudinally.
Ovary superior, bicarpellary syncarpous, unilocular with many anatropous ovules, more or less sunk in the tissue of a free central placenta, rarely ovules only 2; style short or absent, stigma unequally 2-lobed. Fruit a many seeded capsule dehiscing by 2-4 valves or irregularly, or opening circumscissously, rarely fruit indehiscent and 1-seeded. Seeds minute, without endosperm.
The bladder of Uticularia is an egg-shaped structure with a horseshoe-shaped mouth on one side. The mouth is surrounded by a thick ridge or ‘collar’ which is produced at the two ends of the base of the horse-shoe. The two projections bear branched hairs called ‘antenna”.
The mouth is closed by a valve which is attached along the base of the horse-shoe and opens towards inside. Irritable hairs are situated at outer side of the dome which on coming into contact with an insect pass on stimuli that cause the valve to open and the insect is sucked in.
The valve quickly comes back to its original position and the insect is entrapped. The inner wall of the bladder is provided with scattered quadrifid or quadripartite glandular hairs that absorb the decaying material of the insect trapped inside the bladder.
In Pingiucula the simple entire leaves bear glandular hairs which capture tiny insects by a sticky secretion while the margin of the leaf also bends over the insect. The decaying material is made soluble by the secretion and then absorbed. Bladder or pitcher formation is also noticed in other genera of the family.
The floral formula is represented as:
The family is distributed in the tropical and temperate parts of the world and has about 250 species of which Utricularia alone contains about 200- This is represented in India by several species of Utricularia in the plains and the hills and a few species of Pinguicula in the temperate region of the Himalayas.
Family # 11. Acanthaceae:
Acanthaceae are annual or perennial herbs or shrubs, sometimes climbers or twiners, rarely small trees. Leaves are opposite, simple, exstipulate; cystoliths usually present in the leaves. Inflorescence racemose or cymose usually with prominent bracts and bracteoles.
Flowers are small or large, bisexual, hypogynous, strongly zygomorphic. Calyx gamosepalous, 5-partite or 4-partite; lobes unequal, imbricate. Corolla usually bilabiate, sometimes oblique, imbricate or twisted.
Stamens 4, didynamous, epipetalous; anther 2-celled or rarely 1-celled, often spurred and hairy; anther-cells sometimes divergent or one placed slightly above the other; dehiscence of anthers longitudinal or by apical pores; stamens sometimes only 2 with or without staminodes; pollens usually variously sculptured.
Carpels 2; ovary syncarpous, superior, 2-celled with 2 or more anatropous ovules in each cell on axile placenta; style slender, terminal; stigma bilobed, lobes often unequal, sometimes spathulate. Fruit a loculicidal capsule, hard or leathery. Seeds usually supported on hook-like outgrowths of the funicle, the so called retinacula or jaculators; endosperm absent; embryo curved.
Acanthaceae has the floral formula as:
There is comparatively less variation in general habit as well as in floral structure although it is a fairly large family. A few species of Thunbergia and Mendoncia are climbers. Among the shrubby genera a few are arboreal, e.g. Adhatoda, Phlogacanthus, Strobi-lanthus etc.
Some have axillary spines, as in Barleria, Hygrophila, etc. The calyx in Thunbergia is reduced to a narrow ring. Sepals usually connate and 5-lobed, but in Elytraria, Nelsonia, Blepharis, Acanthus, Barleria, etc. calyx is 4-lobed or there are 4 free sepals in opposite pairs.
The corolla is 2-lipped in most cases but in Acanthus, Blepharis, etc. the upper lip is absent. In Symplectochilus the lower lip is roled. In Thunbergia, Ruellia, Hemigraphis, etc. the corolla is 5-lobed.
In Pentstemonacanthus five fertile stamens are present. In other cases they are either 2 or 4. Anther cells are distinct and wide apart in some species of Justicia, Beloperone, Salviacanthus, etc., sometimes one placed higher than the other, e.g. Justicia, Adhatoda, Rhinacanthus, Peristrophe, etc., and rarely spurred, e.g., Dyschoriste, Justicia, Monechma, etc.
Pollens are of different shape and size and vary much as regards the sculpturing of the exine. A hard retinaculum is present in the fruit of many genera and is absent in the others and the family is divided into 2 subfamilies mainly on this character.
The family comprises about 2500 species under 250 genera and is cosmopolitan in its distribution but the majority are in the tropics. Over 500 species occur in India and a few are often gregarious in the hills of S. India, e.g.
Carvia callosa Bremek which is endemic in Malabar hills. Other species common in India are Ecbolium viride (Forsk) Alston, Lepidagathis incurva Don. Rungia repens (L.) Nees., Justicia procumbens Linn., etc. Strobilanthes usually are found in the hills and many species are in S. India and in the Himalayas upto and elevation of 2000 mtrs.
Thunbergia coccinea T. Anders a climber with scarlet flowers occurs in the Himalayas in the subtropical region. Justicia gendarusa Burm. f. an African species is commonly cultivated as a hedge plant and so is Adhatoda zeylamca Med. which is also found wild. Acanthus ilicifolius Linn, is a semihalophytic plant growing in Sunderbans and also in marshy places.
Acanthaceae is closely related to Scrophulariaceae, Labiatae, Verbenaceae and Bignoniaceae. Bignoniaceae is quite distinct being predominantly woody and having compound leaves among other characters.
Fruits of Verbenaceae are drupaceous and of Labiatae are nutlets. Scrophulariaceae has many characters similar to Acanthaceae but may be easily distinguished by absence of retinacula in fruits and pollen grains not ornamented. Acanthaceae and Scrophulariaceae are considered to have originated from same ancestral stock.
Acanthaceae is divided into 2 subfamilies by Lindau as noted below:
I. Thunbergioideae:
Retinacula absent, funicle indistinct; lateral walls in fruit undivided.
Tribe (i) Nelsonieae:
Ovules numerous,—Staurogyne, Nelsonia, etc.
Tribe (ii) Mendoncieae:
Ovules 4, fruit drupacious,—single genus—Mendoncia.
Tribe (iii) Thunbergieae:
Ovules 4; fruit capsular.—Thunbergia, Meyenia, etc.
II. Acanthoideae:
Retinacula and funicle distinct; lateral walls of the fruit bipartite.
Tribe (iv) Contortae:
Corolla lobes usually contorted, never imbricate.—Hygrophila, Ruellia, etc.
Tribe (v) Imbricatae: Corolla lobes imbricate.—Andrographis, Barleria, Justicia, etc.
Economically the family is not very important. A few are reputed for medicinal properties, viz. Adhatoda zeylanica is recommended in cough and cold, Phlogacanthus thyrsiftorus is a febrifuge. Andrographis paniculata Nees. is efficacious in liver troubles, and kills worms.
Roots of Ecbolium are used in jaundice and roots of Rhinacanthus cure skin disease. The juice of the leaves of Justicia gendarusa or a paste of the same is very good for cuts and for ulcers.
The juice is taken in cases of internal haemorrhage with good results. A few species are cultivated in gardens for their large and beautiful flowers e.g. Thunbergia grandiflora Roxb., Barleria prionitis Linn., Crossandra undulifolia Salisb., Justicia betonica Linn., etc.