In this article we will discuss about:- 1. Characters of Malvaceae 2. Distribution of Malvaceae 3. Economic Importance 4. Affinities 5. Important Types.
Characters of Malvaceae:
Stellate hairs on the young parts, mucilaginous juice present, leaves alternate, stipulate, multicostate reticulate; inflorescence solitary or cyme; flower actinomorphic, hermaphrodite, hypogynous, pentamerous, with epicalyx, calyx free or united, corolla free; stamens indefinite, monadelphous; anthers monothecous, stamens united to form a tube; gynoecium many often five, syncarpous, ovary multilocular, superior, axile placentation; fruit schizocarpic carcerulus or capsule.
Pollen grains large spherical, spiny and together with monothecous anthers form one of the distinguishing characters of the family The numerous stamens are supposed to have arisen by multiplication of five epipetalous members.
A. Vegetative characters:
Habit:
The plant are generally herbs (Abutilon, Malva, Sida, Urena), shrubs (Hibiscus, Gossypium), and a few trees (Gossypium arboreum) with a mucilaginous sap in all parts. Usually young parts of the plants are covered with stellate hairs.
Root:
Tap, root, branched.
Stem:
Herbaceous (Malva) or woody (Hibiscus), branched, erect or spreading (Sida, Malva parviflora) pubescent with stellate hairs.
Leaves:
Alternate, petiolate, stipulate, stipules deciduous (Malva), simple, entire or palmately divided or lobed, margin wavy or serrate, apex acute, multicostate reticulate venation.
B. Floral characters:
Inflorescence:
Solitary axillary (Hibiscus, Urena), solitary terminal (Abutilon), raceme (Althaea), panicle (Kydia).
Flower:
Pedicellate, bracteate, bracteolate in the form of epicalyx, hermaphrodite rarely unisexual (Napaea), complete, actinomorphic, pentamerous, hypogynous.
Epicalyx:
Epicalyx 3 (Gossypium), 7 to 9 (Althaea) and in a few totally absent (Abutilon, Sida).
Calyx:
Sepals five, connate at the base, persistent, sometimes forming a tube (Urena), valvate aestivation.
Corolla:
Petals 5, polypetalous sometimes slightly connate at the base with the staminal tube-thus epipetalous, large showy, twisted. Prominent veins can be observed on the petals.
Androecium:
Stamens indefinite, monadelphous, forming a staminal tube; epipetalous staminal tube united with the corolla, anthers monothecous, reniform, basifixed, filament short, introrse.
Gynoecium:
Multicarpellary usually five (Hibiscus) or ten (Althaea) indefinite (Abutilon) or 3 (Kydia); syncarpous, ovary superior, penta or multilocular with axile placentation, ovules one to many in each loculus; style one, long, passing through the staminal tube; stigma correspond to the number of carpels.
Fruit:
Schizocarpic carcerulus (Abutilon, Malva, Sida), capsule (Hibiscus, Gossypium), berry (Malvaviscus).
Seed:
Non-endospermic, in some genera seed coat is densely tomentose (Gossypium).
Pollination:
Entomophilous. Insects are attracted for nectar, showy nature of corolla and protandrous flowers.
Floral formula:
Distribution of Malvaceae:
It is commonly called cotton family or mallow family. The family consists of about 85 genera and 1500 species among which 111 species found in India. The plants are almost cosmopolitan in distribution but many of which are confined to tropics and sub-tropics.
Economic Importance of Malvaceae:
Economically this family is of much importance because there are a number of fibre yielding plants. According to certain authorities nearly all genera can produce some or other kinds of fibres.
A. Fibre yielding plants:
1. Cotton is perhaps the most important fibre inspite of many synthetic textile fibres. The seed coat of Gossypium produce epidermal hairs which is cellulosic in nature. This is cotton wool. These hairs are flattened, twisted and from the staple. Cotton plant grows best in the sandy damp soil of humid regions.
Egyptian cotton is derived from G. peruvianum whose staple length is 4 7/8 cms. G. barbadense produces sea inland cotton; its staple length in 5 cms. G. hirsutum is a native American species and is also considered superior cotton. The main Indian species is G. herbaceum; its staple length is 1 7/8 cms. G. arboreun is a small tree or a large shrub. It is also cultivated in India.
Cotton seed is further important for it produces an edible oil which is semidrying and useful as oleomargarine and in soap. The oil cake is also a very nourishing cattle feed. The residue is also used in washing powder, in preparation of oil cloth, artificial leather, nitroglycerine etc.
2. Hibiscus cannabinus (Hindi-Patsan, Deccan Hemp or Bilipatam Jute) produces a very valuable fibre from its stem which is used for making rope, cordage, coarse canvas, sacs, floor matting. It is thus used as a substitute for jute.
3. Hibiscus sabdariffa, (Hindi-Patwa). A strong silky brown fibre is produced from its stem. This is a good substitute for jute in textile and paper industry.
4. Other species of Hibiscus also produce fibres of minor importance. H. tiliaceous produces majanga fibres. Abelmoschus esculentus gives okra fibres.
5. Abutilon theophrasti (syn. A. avicennai) produces China jute or Indian mallow. It is extensively cultivated in China. It takes up dyes quickly and used in making rugs.
6. Urena lobata – It is a weed in all tropical countries and furnishes a yellowish fibre that lasts longer than jute and is used as a substitute at some places. In Barazil it is used for making coffee sacks.
7. Malachra capitata also produces a strong silky fibre like jute and used as a substitute.
B. Miscellaneous uses:
8. Abelmoschus esculentus (Hindi-Bhindi, Eng.-Lady’s finger) fruits are used as a vegetable.
9. Hibiscus rosa-sinesis or shoe flower is widely cultivated as an ornamental plant and also used in the worship of God and Godess Kali. Althea rosea is also a garden plant with its lovely pinkish flowers. Abutilon indicum (Hindi-Kanghi) is a wild plant which is sometimes used medicinally.
Malva sylvestris is also a garden plant. Urena repanda is supposed to be a cure for hydrophobia.
Affinities of Malvaceae:
Malvaceae is related to Sterculiaceae and Tiliaceae in having mucilaginous sap, simple alternate and stipulate leaves. According to Bentham and Hooker it differs from them in having monothecous anthers, monadelphous condition and presence of involucre or epicalyx.
Hutchinson placed the single family under Malvales. Engler and Prantl put this family together with Tiliaceae, Bombaceae and Sterculiaceae in the order Malvales.
Primitive characters:
1. Presence of mucilage in plant parts.
2. Some plants are shrubs and tree-like.
3. Leaves alternate, simple, stipulate.
4. Flowers solitary, hermaphrodite, hypogynous, actinomorphic and bracteate.
5. Presence of epicalyx.
6. Corolla free.
7. Gynoecium polycarpellary {Abutilon).
8. Seeds endospermic.
Advanced characters:
1. Many plants are annual herbs.
2. Epicalyx absent in some genera (Abutilon, Sida).
3. Calyx gamosepalous.
4. Stamens monadelphous and anthers monothecous.
5. Gynoecium syncarpous.
6. Fruit simple.
Common plants of the family:
1. Althaea – Commonly called Holly-hock and cultivated in gardens for flowers.
2. Abutilon – (H. Kanghi) A weed of road side and waste places, epicalyx absent.
3. Hibiscus rosa-sinensis – Cultivated in gardens for flowers.
4. Gossypium – Cultivated for cotton.
5. Sida – Wild herb and epicalyx absent.
6. Malva – Wild winter herb having reniform leaves and white flowers.
7. Abelmoschus – A large genus of herbs, shrubs and trees.
Division of the family and chief genera:
Schumann divided the family Malvaceae in two groups and four tribes on the basis of carpel arrangement.
Group A. Carpels arranged in vertical rows:
(i) Malopeae:
Carpels indefinite, each one ovuled. Malope, Kitaibelia.
Group B. Carpels in one plane and whorled:
(ii) Malveae:
Styles as many as carpels, fruit schizocarpic. Abutilon, Althacea, Malva, Sida, Anoda, Lavatera.
(iii) Ureneae:
Styles twice the number of carpels, fruit schizocarpic. Urena, Goethea, Pavonia.
(iv) Hibisceae:
Fruit capsule.
Important Types of Malvaceae:
1. Althaea rosea (Fig. 38.5):
Habit:
Tall ornamental annual herb.
Root:
Tap, branched and annual.
Stem:
Erect, cylindrical, green, hairy, woody and solid.
Leaves:
Alternate, stipulate, petiolate, simple, palmati-lobed with a cordate base, multicostate reticulate venation.
Inflorescence:
Solitary axillary.
Flower:
Bracteate, pedicellate, complete, actinomorphic, hermaphrodite, pentamerous, hypogynous, and showy.
Epicalyx:
7 – partite, green, hairy.
Calyx:
Sepals 5, gamosepalous, campanulate, green, densely hairy, inferior.
Corolla:
Petals 5, polypetalous, united below with staminal tube, twisted aestivation, hairy at the base, inferior.
Androecium:
Stamens numerous, monadelphous forming a staminal tube, filaments short, epipetalous; anthers reniform, monothecous.
Gynoecium:
Polycarpellary, syncarpous, ovary superior, multilocular, one ovule in each loculus, axile placentation; style long, number as many as carpels; stigma linear.
Floral formula:
2. Malva sylvestris (Fig. 38.2):
Habit:
An annual herb.
Root:
Tap and branched root system.
Stem:
Herbaceous, erect, cylindrical, solid, branched, hairy, mucilaginous.
Leaves:
Alternate, petiolate, simple, stipulate, margin crenate, obtuse, upper surface smooth and lower hairy, multicostate reticulate venation.
Infloresence:
Axillary cyme.
Flower:
Pedicellate, bracteate, bracteoles in the form of 3 epicalyx, hermaphrodite, actinomorphic, hypogynous, pentamerous.
Calyx:
Sepals 5, gamosepalous, persistent, hairy, valvate aestivation, inferior.
Corolla:
Petals 5, polypetalous, slightly united at the base, twisted aestivation, inferior.
Androecium:
Stamen indefinite, monadelphous, forming a staminal tube, epipetalous, anther monothecous.
Gynoecium:
Polycarpellary, syncarpous; ovary superior, multilocular, axile placentation; style as many as carpels and passing through staminal tube, stigma equal to carpels.
Floral formula:
3. Hibiscus rosa-sinensis (Fig. 38.3 and 38.4):
Habit and Habitat:
An ornamental shrub, cultivated in tropics; perennial.
Root:
Tap, branched and deep.
Stem:
Erect, branched, cylindrical, solid, woody, glabrous.
Leaf:
Alternate, simple, petiolate, stipulate, ovate, serrate margin, acute apex, glabrous, unicostate reticulate venation.
Inflorescence:
Solitary axillary.
Flower:
Ebracteate, pedicellate, complete, actinomorphic, hermaphrodite, pentamerous, hypogynous, large, showy, red, mucilaginous.
Epicalyx:
Five to seven, green, linear.
Calyx:
Sepals 5, gamosepalous, ovate, campanulate, valvate and inferior.
Corolla:
Petals 5, polypetalous, mucilaginous, twisted, red, united at the base and adnate to the staminal tube.
Androecium:
Stamens numerous, forming a tube, monadelphous, epipetalous, anthers monothecous, yellow, reniform, extrorse, transversely attached to the filament, pollen grains multiporate.
Gynoecium:
Pentacarpellary, syncarpous, superior, pentalocular, axile placentation, many ovules in each loculus; style passing through the staminal tube; stigma 5 capitate, covered with velvety growth.
Fruit:
Capsule.
Seed:
Endospermic.
Floral formula:
4. Gossypium (Fig. 38.6 & 38.7):
Habit and habitat:
A cultivated shrub, for fibres and oil.
Root:
A much branched, deep, tap.
Stem:
Erect, woody in mature plants, cylindrical, branched, solid, hairy.
Leaf:
Ramal, cauline, simple, alternate, petiolate, stipulate, palmately 3-5 lobed, hairy, divergent multicostate reticulate.
Inflorescence:
Solitary in leaf axil, sometimes axillary cymose.
Flower:
Ebracteate, pedicellate, complete, regular, actinomorphic, hermaphrodite, hypogynous, large, yellow.
Epicalyx:
3, united, large.
Calyx:
Sepals 5, gamosepalous, cupulate, hairy, inferior.
Corolla:
Petals 5, polypetalous, obovate, mucilaginous, yellow, twisted, inferior.
Androecium:
Stamens many, monadelphous, epipetalous, forming a tube, anthers monothecous, reniform, transversely attached to the filament, extrorse.
Gynoecium:
Pentacarpellary, syncarpous, ovary superior, pentalocular, axile placentation, many ovules in each loculus, style simple, stigma 5, capitate.
Fruit:
A five valved capsule.
Seed:
Endospermic; densely covered with fibres.
Floral formula:
Literature:
1. Schumann, K. 1895 : Tiliaceae, Malvaceae and Bombaceae. Die Nat. Pflanzenfamilien III (6): 30-53.
2. Webber, I.E. 1934 : Systematic anatomy of the woods of Malvaceae. Trop. Wood 38 : 15-36.