Here is a list of twenty-eight Pteridophytes:- 1. Psilotum 2. Lycopodium 3. Selaginella 4. Isoetes 5. Equisetum 6. Ophioglossum 7. Botrychium 8. Lygodium 9. Gleichenia 10. Cyathea 11. Hymenophyllum 12. Asplenium 13. Pleoplatis 14. Blechnum 15. Lindsaea 16. Cheilanthes 17. Pteris 18. Polystichum 19. Oleandra 20. Dryopteris and a few others.
1. Psilotum:
Plant Body (Sporophyte):
It is dichotomously branched with rhizome hidden under humus. Aerial shoot is green, slender, somewhat cylindrical to furrow at Upper region with the presence of scaly appendages and sporangia on the uppermost, aerial shoat axis.
Internally, the aerial shoot (stem) shows a siphonostelic vascular system which becomes actinostelic in the younger branches. Epidermis is single layered with heavily cuticularised outer wall and stomata in the furrows.
The cortex is massive and divisible into three zones – outer cortex (hypodermal zone composed of chlorenchymatous tissue), middle cortex (composed of sclerenchymatous tissue) and inner cortex (composed of thin walled parenchymatous tissue).
The cortical tissue is bounded inwardly by the endodermal layer which shows casparian strips on the radial walls. Xylem is surrounded by phloem. There is a conspicuous sclerotic pith with xylary tissues. Xylem is usually six rayed (Fig 6.1).
Reproductive Structure:
Sporangium:
It is mostly located at the distal end of the shoot. Each mature sporangium is 3-lobed, 2 to 3 mm wide and closely clasped with stem axis by a minute forked foliar appendage. In T.S. through sporangium it appears that each lobe contains a spore chamber with numerous spores within a multi-layered wall.
Spore:
The spores are bilaterally symmetrical while the walls are thick and reticulate (Fig 6.2).
Identification:
Plant body rootless, leafless, dichotomously branched sporophytic type, aerial shoots with rudimentary scale leaves and having terminal or lateral sporangia, presence of simple vascular supply (mostly protostelic, rarely primitive siphonostelic type.
CLASS: PSILOTOPSIDA
The class has only one order.
ORDER: PSILOTALES
The order has only one family.
FAMILY: PSILOTACEAE
Dichotomously branched plant body with rudimentary scale leaves, sporangium 3 lobed and closely clasped by minute, forked foliar appendage.
GENUS: PSILOTUM
2. Lycopodium:
Plant Body (Sporophyte):
In general, the plants are herbaceous, erect or pendent. The stems are densely covered with microphylls and are protostelic. It is mostly strobilus forming with the sporangia on the adaxial face of the sporophylls. The genera Lycopadium is now splitted into Lycopodiwn, Huperzia, Lepidotis & Phlegmarius.
The gross morphology of plant body in some Indian species (Fig 6.3) is discussed below:
Lycopodium elavatum:
The plant has a weak, prostrate stem trailing along the surface and with adventitious roots growing from anywhere on the lower surface. The branching is monopodial. The stem is closely covered spirally by small, simple (microphyllous), sessile, lanceolate leaves with mildly serrate margins and single median veins. The sporangia are developed in strobili’s, which are terminal and slender.
Lepidotis cernua (L) Franco. et Vasco. (Lycopodium cernuum L):
It is small and somewhat prostrate herb and about 45 – 90 cm long. It is branched and branching is found towards the apex, leaves are small, microphyllous and spirally arranged on the stem. Sporangia are aggregated into a small strobilus (5 – 7 mm in length) and situated at the tip of all aerial branches.
Huperzia squamosa (Forst) Rothm. (Lycopodium squarrosum Forst):
It is a small, herbaceous, pendulous plant mostly growing as epiphyte on tree trunk. Leaves are microphyllous and spirally arranged. Sporangia are aggregated into a lax strobilus at the terminal parts of the aerial branches.
Huperzia serrata (Thunb.) Rothm. (Lycopodium serratum Thunb.):
It is a small, erect, rooted and dichotomously branched, herbaceous plant. Leaves are microphyllous, lanceolate, with distinctly serrate margin. On the stem leaves are loosely arranged in spiral fashion. Sporangia are found in the axils of sporophylls without forming any strobilus. Sporophylls are comparatively smaller than leaves.
Huperzia hamiltonii (spring) Sen & Sen (Lycopodium hamiltonii Spring ex Hook, et Grev.):
Plants are small, erect, rooted, and dichotomously branched, terrestrial herbs. Leaves are spathulate, lanceolate with smooth margin and arranged spirally on stem. Sporangia are borne in the axils of loosely arranged sporophylls towards the apical region of the stem.
Phlegmarius phlegmaria (L) Sen & Sen (Lycopodium phlegmaria L.):
Plants are dichotomously branched, pendent, epiphytic herbs. Leaves are ovate to lanceolate, microphyllous and spirally arranged. The leaf apex is acute and margin is smooth. Sporangia are aggregated to form strobilus. Sporophylls are smaller in size than sporangia. Strobili are long, cylindrical and pendent.
Huperzia selago (L) Bernh. ex Schrank et Mart. (Lycopodium selago L.):
It is small, dichotomously branched, erect herb with distinct root system. Leaves are microphyllous, linear and spirally arranged. The arrangement of the leaves is lose all through except the apical growing zone. Sporangia are borne in the axil of some leaves and there are distinct sterile (vegetative leaves) and fertile (sporophylls) patches on the stem. There is no strobilus formation.
Internal Structure:
Transverse section of the stem is round or somewhat fluted. It shows an epidermis of one layer thickness with scattered stomata. Below it there is a thick cortex traversed by leaf trace bundles. The outer layers of cortex are sclerenchymatous while the inner layers are parenchymatous. The cortex is bounded on the inside by a layer of endodermis with the usual thickened radial walls (Casparian strips).
Internal to the endodermis, there are one or more layers of parenchamatous pericycle. The stele is protostelic without any cambium. In different species the stellar type varies distinctly. In Lycopodium clavatum stele is plectostelic, i.e. xylem element, are arranged in more or less parallel plates with the phloem in between these patches.
In Huperzia serrata (Lycopodium serratum) the stele is actinostelic i.e. xylem elements are arranged in star-shaped manner, which is surrounded by phloem. In Lepidotis cernuum (Lycopodium cernuum) the stele is a mixed protostele, where the stellar structure is broken up extensively so that a meshwork of innumerable xylem patches with surrounding phloem tissue is formed (Fig 6.4).
Anatomically, leaf is very simple with a one-layered epidermis broken by stomata, a uniform parenchymatous mesophyll with several air spaces and a median concentric vascular bundle. The anatomy of the root also shows simplicity, i.e., single layered epiblema, a few layered cortex, one layered endodermis and monarch stele.
Reproductive Structure:
Strobilus:
It is formed by the aggregation of sporangia bearing sporophylls. Sporophylls are lanceolate to ovate. Each sporophyll bears a sporangium on its adaxial surface. Most of the species have strobiloid reproductive structure. Only a few species have sporophylls loosely arranged. In 1.s. through strobilus, sporophylls with sporangia are seen on both sides of the axis.
Sporophyll:
It is somewhat smaller than vegetative leaf and lanceolate to ovate in shape. The margin may be smooth or serrate. Sporagium is situated at the base of the sporophyll. Except in a few species, sporangia are fully covered by sporophylls. The sporophylls are of one type only, i.e., micros-porous. So, it is homosporous.
Sporangium:
It is coriaceous, reniform to orbicular, compressed, 1-celled and dehiscing by a split down the apex from end to end.
Spore:
Spores are tetrahedral with a sculptured exine and a triradiate ridge (Fig 6.5).
Identification:
Plant body differentiated into shoot with stem and leaf and root, leaves microphyllous, stem mostly protostelic, homo- or heterosporous, sporangium on the upper axil of sporophyll.
CLASS: LYCOPSIDA
Plant body devoid of secondary growth, leaves eligulate, definite stobili present, homosporous.
ORDER: LYCOPODIALES
Plant herbaceous with definite strobilus.
FAMILY: LYCOPODIACEAE
Stem with protostelic core, strobili at the terminal part of the aerial branches, leaves eligulbte, sporophylls smaller in size than: the vegetative leaves.
GENUS: LYCOPODIUM
3. Selaginella:
Plant Body (Sporophyte):
The plant is herbaceous with copiously branching stem, the ultimate divisions usually flabellately dichotomous, trailing, sub-erect or scandent. There is conspicuous presence of rhizophores (root) which grow vertically down from the forking of the dichotomies. Adventitious roots develop where the rhizophores meet the soil.
There are four rows of leaves – two rows of smaller leaves (median leaves) on the upper side and two rows of larger leaves (lateral leaves) on the lower side, there being one large and one small leaf at each node. The leaves are microphyllous, lanceolate to ovate and mostly arranged in an anisophyllous opposite order though in some species the arrangement may look spiral.
Each leaf bears on its upper surface near its base one small membranous, tongue-like outgrowth called the ligule. At the tip of each branch there is a sporangiferous spike or strobilus. The strobilus is formed by the aggregation of sporophylls with sporangia.
The gross morphology of some Indian species (Fig 6.6) is described below:
Selanginella indica (Milde) Trayon:
The plant has a tendency to be upright with radially arranged, more or less uniform (isophyllous) leaves.
Selaginella pentagona Spring:
The plant has an erect stem axis with branches. Branches are devoid of hairs, and do not curl up when dry. Median leaves are serrulate, axillary leaves denticulate.
Selaginella monospora Spring:
The plant bears branches at the base. Lateral leaves are obtuse, median leaves are acuminate.
Selaginella repanda (Desv. ex. Poir.) Spring:
The plant has a strong erect stem, and root develops at the base only. Leaves are dimorphic and distributed throughout the stem.
Selaginella bryoptesis (L) Bak:
The plant has a short erect stem with branches without any hairs. Lateral leaves bear marginal sclerotic sheath. The branches curl up when dry.
In T.S. through the stem of Selaginella the following layers are noticed:
(a) A single layer of epidermal prosenchymatous tissue without any stomatal opening.
(b) A few layers of angular parenchymatous cortex usually without intercellular spaces.
(c) The innermost cortical layer, i.e., endodermal layer is modified into tubular trabeculae.
(d) The vascular cylinder varies in different species from protostelic to siphonostelic type and monostelic to polystelic. In 5. kraussiana stele is distelic. Each stele has a pericycle enclosing a simple protostele or siphonostele.(Fig 6.7).
A T.S. of the rhizophore shows a monarch stele surrounded by cortex of a few layer thickness and externally bounded by epidermis.
A T.S. of the leaf shows a one layered epidermis (both upper and lower) and in between chlorophyllous mesophyll cells and a simple vascular bundle.
Reproductive Structure:
Strobilus:
It is formed by the compactly arranged sporophylls on the terminal parts of the aerial branches. In L.S. view through strobilus, the sporophylls with sporangia are seen on both sides of the axis.
Sporophyll:
The sporophylls are all alike resembling the larger vegetative leaves but the sporangia are of two types (heterosporous) – microsporangia and mega-sporangia, so that the sporophylls also are called micro-sporophylls and megasporophylls. The sporophylls are spirally arranged on the axis in a compact manner to form a strobilus or sporangiferous spike.
In some species micro and megasporophylls are borne on separate strobili while in other species, the two kinds of sporophylls are borne on the same strobili-microsporophyll’s are on top and megasporophylls below or the micro-sporophylls are on one side of the strobili while the megasporophylls are on the other vertical side.
Sporangia:
In mature microsporangium, there are many microspores (usually in tetrad form) surrounded by 2 – 3 cells thick tapetum layer.
In mature mega-sporangium the tapetal layer encloses a few large thick-walled megaspores.
Thus, the species are heterosporous.
Spore:
The microspores are very small and with a 2-layered wall exinc and intine. The exine is usually ornamented with spines. Its shape is more or less tetrahedral with one side rounded. The megaspore shows a thick and sculptured exine and thin intine. A triradiate ridge is prominent on the top of the tetrahedral structure (Fig 6.8).
Identification:
Sporophyte differentiated into leaf, stem and root, leaves microphyllous, each sporophyll bears one axial sporangia, proto-to siphonostelic type stem axis.
CLASS: LYCOPSIDA
Terrestrial sporophyte with primary growth only, no vascular cambium; leaves microphyllous, ligulate; heterosporous.
ORDER: SELAGINELLALES
Stem mono – or polyprotostelic or siphonostelic; sporangia short stalked, single, near the axil of a leaf.
FAMILY: SELAGINELLACEAE
Leaves distinctly ligulate; presence of trabeculated endodermal zone in the stem axis ; two types of sporangia with sporophylls, microsporangia with many microspores and mega-sporangia with a few megaspores.
GENUS: SELAGINELLA
4. Isoetes:
Plant Body (Sporophyte):
The plant appears as ordinary tufted grass. The stem is short and 2-3 lobed, corm like structure which is covered by long, stiff, awl-shaped leaves. The entire plant is 10 – 50 cm. high.
The leaves are borne in acropetal order overlapping one another and taper abruptly from a broad base to an elongated acicular limb. The leaves are ligulate and microphyllous, i.e., each leaf has a single median vein. The lowermost leaves are sterile, while the upper leaves bear sporangia, i.e., they are fertile.
A T.S. of mature stem shows a number of tissue zones, viz.
a) There is a massive parenchymatous cortex (Primary) which forms the bulk of the stock. This is homogenous, full of starch and has big intercellular spaces and leaf traces.
b) External to the cortex, there are conspicuous leaf base parts, which are, of course, parenchymatous.
c) The internal core bounded by cortex stele which is protostelic, i.e., central xylem is surrounded by phloem. Cambium develops outside the phloem and produces secondary tissue called prismatic layer.
A T.S. of leaf shows a single collateral vascular bundle continuous with the leaf trace. There are four longitudinal air chambers running along the whole length of the acicular part. These are transversely barred. Leaf epidermis often shows stomata.
A T.S. of root shows a monarch protostele on one side of a central air space; xylem and phloem are almost collateral. There is a clear endodermis outside the stele. The stele is surrounded by parenchymatous cortex and delicate epidermis. (Fig 6.9).
Reproductive Structure:
Sporophylls:
All upper leaves are sporophyllous. A sporophyll bears a single flattened, oval or rounded sporangium between the ligule and the leaf base on the adaxial face. The sporangium is located within a depression in the leaf/ base and is completely or incompletely roofed by a membranous outgrowth arising from the base of the ligule which is called the velum.
In each mature sporangium there are a few transverse plates called trabeculae which incompletely divide the cavity within the mature sporangium. There are two different kinds of sporophylls and sporangia: microsporophyll’s with microsporangia and megasporophylls with mega sporangia.
Microspores are many per sporangium, while megaspores are larger and only a few per sporangium. The microspores are bilateral, lenticular while the megaspores are tetrahedral (Fig 6.10).
Identification:
Presence of well-differentiated plant body leaves microphyllous with single median veins, stele protostelic to siphonostelic, sporophylls with a single sporangium on the adaxial face near its base.
CLASS: LYCOPSIDA
Stem axis condensed rhizomorph like, leaves microphyllous and ligulate, heterosporous without strobiloid organisation.
ORDER: ISOETALES
Stem protostelic; leaves borne in a close spiral, more or less acicular; sporangia very large, sessile and trabeculated.
FAMILY: ISOETACEAE
Marshy or aquatic plants, stem corm like with long, stiff awl-shaped leaves; sporangia situated at the basal expanded portion of the fertile leaf, heterosporous.
GENUS: ISOETES
5. Equisetum:
Plant Body (Sporophyte):
It has an erect, branched aerial part and a horizontal rhizomatous part with adventitious roots and tubers at the nodes. Both horizontal and aerial shoots are ribbed and differentiated into nodes and internodes. At the nodes, whorls of branches and leaves arranged in whorls are present. Leaves are all microphyllous. Aerial branches are of two kinds,
Sterile aerial branch with lateral branches and fertile aerial branch without lateral branch but terminated with sporangiferous spike called strobilus. The stem, as seen in transverse section, has prominent, alternately arranged ridges and furrows. The outermost covering is the epidermal layer, which is composed of thick walled cells with generous deposition of siliceous material. Sunken stomata, located only in the furrows, are present.
Beneath the epidermis lies the cortex, which exhibits a varied type of organisation. The outer cortex is composed of sclerenchyma and thin walled chlorenchyma. Sclerenchyma is excessively developed opposite the ribs. The air spaces are conspicuously present in the inner cortex zone in between two ridges. This space is called vallecular canal. Opposite each ridge is a vascular bundle of unusual interest.
A T.S. of the internode of a mature stem reveals a protoxylem lacuna (carinal canal) associated with a vascular bundle. Opposite the lacuna is the primary phloem flanked on each side by strands of xylem. Xylem is endarch. Each bundle is covered by endodermis, or both endodermis and pericycle are continuous. In mature stem, hollow pith (pith cavity) is present. It is conspicuous only at the inter-nodal zone. The stem is siphonostelic (Fig 6.11).
Reproductive Structure:
Strobilus:
It terminates a fertile shoot and is composed of whorls of stalked sporangiophores with peltate sporangia. Each sporangiophore is umbrella-like in shape, with pendant sporangia (5 – 10 in number) attached to the underside of the polygonal, disc shaped shield of the sporangiophore. Immediately below the whorls of sporangiophores, the axis bears a ring-like outgrowth, termed anulus.
Sporangium:
Mature sporangia are elongated, cylindrical and open along a single longitudinal line of dehiscence.
Spore:
It is rounded and thick walled with elaters (Fig 6.12).
Identification:
Sporophyte differentiated into stem, leaf and root, stem jointed, siphonostelic; xylem exarch or endarch; sporangia borne oti specialised stalk (sporangiophore) which are organised into strobili, homosporus.
CLASS: SPHENOPSIDA (CALAMOPHYTA)
Stem ribbed, siphonostelic with endarch xylem, presence of conspicuous protoxylem lacunae (carinal canal), spores with elaters.
ORDER: EQUISETALES
Several microphyllous leaves fused together and form a sheath around stem at node, Strobili terminal and consists only of whorled sporangiophores, homosporous.
FAMILY: EQUISETACEAE
Stem jointed, with rough texture, presence of ridges and furrows on stem, presence of sunken stomata in the ferrous, strobili on fertile shoot apex; sporangiophore bears 5-10 peltate sporangia.
GENUS: EQUISETUM
6. Ophioglossum:
Plant Body (Sporophyte):
The plant body has a short, vertical, subterranean rhizome. Several leaves develop spirally from the top. Numerous fairly stout adventitious roots grow from the base of the rhizome.
Each leaf has a thin stipule at its base and is differentiated into a petiole and a lamina. The venation is closed reticulate with some finer veins ending blindly within the meshes. The lamina is entire and lanceolate to ovate. The sporangiferous spike develops at the junction of the petiole and the lamina.
A T.S. of the mature rhizomatous stem shows a broad homogenous cortex which may sometimes show an outer periderm. Cortex shows some leaf traces. The inner stele is siphonostelic with leaf gaps. Each bundle is endarch, and collateral (Fig 6.13).
Reproductive Structure:
Sporangiferous Spike:
It is stalked and bears two rows of sporangia embedded side by side on the apical part of the axis. At maturity, numerous tetrahedral spores are found in each sporangium which is liberated through a slit in the sporangial wall, perpendicular to the wide surface of the fertile spike (Fig 6.14).
Identification:
Plant body differentiated into rhizomatous stem, leaf and roots, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FIUCOPSIDA
Absence of circinate venation of developing leaf, sporangia aggregate in a special kind of spike; gametophyte subterranean, cylindrical.
ORDER: OPHIOGLOSSALES
Sporangia on a fertile spike growing from the adaxial face of the leaf at the juncture of the lamina and the petiole.
FAMILY: OPHIOGLOSSACEAE
Leaves simple, entire or deeply lobed with reticulate veination; spike simple, un-branched. Sporangia embedded on the sterile tissue of the spike.
GENUS: OPHIOGLOSSUM
7. Botrychium:
Plant Body (Sporophyte):
The plant axis is typically a short, stocky, subterranean rhizome from which roots arise at the base of the frond. The frond is fleshy and consists of two parts: the vegetative lamina (blade), which is pinnately branched and a fertile spike, which is also similarly branched, bearing sporangia in two rows on ultimate branches.
A T.S. through rhizome shows massive cortex, central pith and siphonostelic vascular cylinder with leaf traces. Vascular bundles are collateral and endarch. A periderm is present at the periphery of the broad cortex.
Reproductive Structure:
Sporangiferous Spike (Fertile Frond):
The fertile segment is pinnately branched, bearing sporangia in two rows on branches. Each sporangium has several layers of tapetum. At maturity each sporangium is large and has a vascular strand that extends to the base of the capsule. Each sporangium, which dehisces by means of a terminal slit, produces numerous tetrahedral spores (Fig 6.15).
Identification:
Plant body differentiated into rhizomatous stem, leaf and roots; leaf megaphyllous, sporangia aggregate on the leaf margin as soon.
CLASS: FILICOPSIDA
Absence of circinate venation of developing leaf, sporangia aggregate in a special kind of spike; gametophyte subterranean, cylindrical.
ORDER: OPHIOGLOSSALES
Sporangia on a fertile spike growing from the adaxial face of the leaf at the juncture of the lamina and the petiole.
FAMILY: OPHIOGLOSSACEAE
Leaves compound, pinnate, sporangiferous spike branched with sporangia in two rows on the terminal branchlets.
GENUS: BOTRYCHIUM
8. Lygodium:
Plant Body (Sporophyte):
Stem is short to long, creeping, slender and frequency branched. It bears trichomes and a few to many fibrous roots. Leaves are pinnately branched, pinnae partially dimorphic — sterile and fertile lobes, the latter with sori. Pinna is short-stalked and pseudo-dichotomously branched. Each pinna has free to partially anastomosing veins. A T.S. through mature stem shows massive cortex and central protostelic cylinder.
Reproductive Structure:
Sporangium:
Marginal lobes bearing sporangia are very much characteristic. The laminar flange that covers each sporangium serves as an indusium. Spores are tetrahedral, globose, and trilete type. (Fig 6.16).
Identification:
Plant body differentiated into rhizomatous stem, leaf and roots, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf magaphyllous of 1 or 2 types, sporangia in sori, indusiate or ex-indusiate, sporangia development sequential simultaneous.
ORDER: POLYPODIALES
Stem creeping or ascending, sporangia borne singly along the leaf margins, often covered by a flap-like growth of the leaf (indusium).
FAMILY: SCHIZAEACEAE
Leaves pinnate, sporangia develop in spikes and do not develop sori; cap like annulus present.
GENUS: LYGODIUM
9. Gleichenia:
Plant Body (Sporophyte):
The plant has long, creeping dichotomously branched rhizomes clothed with scales or hairs. Leaves are restricted to the upper side of the rhizome in a single row with adventitious roots on the underside of the rhizome. Leaves are pinnate, with pinnatisect penultimate segments and laminar buds with fimbriate scales are present. Pinnae have simple, open veins and each ultimate segmeni bears a single sorus.
A T.S. of stem shows central protostelic to siphonostelic core surrounded by cortex.
Reproductive Structure:
Sporangium:
A few sporangia are grouped together to form sori, which lie on the ultimate segments of pinnules. Sporangia lie on two sides of the midrib of the pinnules. All sporangia develop simultaneously. Each sporangium has a large number of spores and has an obliquely transverse complete annulus which causes vertical dehiscence.
Spore:
It is spheroidal, homosporous and trilete and has slightly papillate surface (Fig 6.17).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root; leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf magaphyllous, of 1 or 2 types, sporangia in sori, indusiate or ex-indusiate, sporangia development sequential simultaneous.
ORDER: POLYPODIALES
Stem rhizomatous, long, creeping with scales and hairs, leaves pinnately compound, sporangia in sori without indusia, lies on two sides of the midrib of pinnules.
FAMILY: GLEICHENIACEAE
Sporangia grouped indefinite clusters of 6 – 8; sporangia with oblique annulus, lateral veins parallel and forked.
GENUS: GLEICHENIA
10. Cyathea:
Plant Body (Sporophyte):
The plant has erect, stout, tall stem with treelike habit. Stem surface is covered with scales. Leaves are large, monomorphic, 2 – 6 m long and borne in a spreading crown at the upper part of the stem. Lamina is unipinnate, with entire pinnae. Pinnae bear free veins with costal areolae. The stripes are spiny and/or scaly, sometimes with aphlebia (abortive pinnae).
Reproductive Structure:
Sporangium:
A few sporangia are aggregated together to form sorus. Each sorus is rounded and borne on the veins on the under surface, often at a fork. Sori are gradade, cup shaped indusium is present. Receptacle is globose to elongate with short to moderately long paraphyses, indusium hemitelioid to sphaeropteroid. Annulus obliquely vertical with stomium dehiscing by transverse split.
Spore:
Spores with three prominent angles, tetrahedral, globose, trilete, surface even or verrucate, porate (Fig 6.18).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangia with indusium, sporangial development gradate or mixed.
ORDER: POLYPODIALES
Stem and petiole bearing only scales; Leaves pinnately branched, monomorphic; sporangia in abaxial sori.
FAMILY: CYATHEACEAE
Sori with long paraphyses, indusiate; spores tetrahedral, globose, trilete, surface verrucate.
GENUS: CYATIIEA
11. Hymenophyllum:
Plant Body (Sporophyte):
Plants are epiphytic with long-creeping rhizomes. Fronds are 1 veined, broad, lanceolate- oblong, bi-pinnatifid, and leaf segment hairy. Sori are located on terminal part of the leaf segments of upper pinnae; lips of indusium always well developed.
Reproductive Structure:
Sporangium:
Sporangia are grouped inter sori, sori more or less elongate. Receptacle is incited within indusium and not paraphysate. Indusium is more or less deeply bi-valvate.
Spore:
Spores are tetrahedral, globose and trilete (Fig 6.19).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plant homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem long-creeping, leaves pinnate, sporangia borne in marginal sori on a short to elongate receptacle, enclosed by a bivalved receptacle.
FAMILY: HYMENOPHYLLACEAE
Lamina 1-2 pinnate lobed, receptacle included, indusium bivalved.
GENUS: HYMENOPHYLLUM
12. Asplenium:
Plant Body (Sporophyte):
The plant body bears an erect to decumbent, stout stem with scales and fibrous roots. Leaves are monomorphic megaphyllous and borne in a cluster. Lamina is simple, entire, glabrous and veins are free.
A T.S. of stem shows dictyostelic condition.
Reproductive Structure:
Sporangium:
Sporangia are borne in clusters forming sori. Each sorus is elongate to long and borne on a nearly unmodified vein wall back of the tip, and also covered by a double flap-like indusium attached to the vein. Sori lie usually parallel or at wide angle to the costa. Sporangium is stalked and bears vertical to oblique annulus.
Spore:
Spores are more or less ellipsoidal to spheroidal, monolete and somewhat perforate (Fig 6.20).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with indusium, sporangial development gradate or mixed.
ORDER: POLYPODIALES
Sori elongate to long, borne on a vein, covered by a short to very long indusium; sporangia long stalked, annulus interrupted by the stalk, homosporous.
FAMILY: ASPLENIACEAE
Leaves pinnate, entire, glabrous, sori elongate to long, sori borne on veins and indusiate; sori lie at wide angle or parallel to the veins; sporangia stalked, spores spheroidal and monolete.
GENUS: ASPLENIUM
13. Pleopeltis:
Plant Body (Sporophyte):
The plant bears long, slender and creeping stem which is covered by clathrate scales and many fibrous roots. Leaves are monomorphic borne at intervals. Lamina is simple entire, lanceolate, glabrous and with veins anastomosing with each other.
A T.S. through the stem shows dictyostelic condition.
Reproductive Structure:
Sporangium:
Sporangia are borne in clusters to form sori on the inframarginal commissures. Sori are round to elongate and borne at the junction of two or more veins. They are slightly raised and ex-indusiate. There are many, persistent, filamentous, branched paraphyses in the sorus. Paraphyses cover the immature sporangia. Sporangium is stalked and annulus is vertical in position.
Spore:
Spores are ellipsoidal, monolete and with verrucate surface. (Fig 6.21).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangia with indusium, sporangial development gradate or mixed.
ORDER: POLYPODIALES
Several sporangia grouped together to form sorus on ventral surface of leaf, homosporous, sporangia stalked, annulus vertical.
FAMILY: POLYPODIACEAE
Sporangium stalked (2 rowed), spores ellipsoidal, monolete.
TRIBE: POLYPODIEAE
Sporangia borne on a long inframarginal commissure, sporangia borne in round to elongate sori, immature sori covered by stalked, peltate, roundish paraphyses ; spore ellipsoidal, monolete.
GENUS: PLEOPELTIS
14. Blechnum:
Plant Body (Sporophyte):
The plant bears erect to somewhat creeping stem. Stem surface is covered with scales and fibrous roots. Leaves are monomorphic and unipinnate, glabrous and with free veins. The rhizome is dictyostelic.
Reproductive Structure:
Sporangium:
Sporangia are aggregated together forming coenosori. Sori are borne on vascular commissures usually near the segment axis. Sori are long and lie parallel to midrib in a single line. Each sorus is covered by a membranous indusium open towards the axis. Sporangia stalked, 2 rowed and bear vertical annulus.
Spore:
Spores are elliptical, monolete, slightly papillate to smooth and homosporous (Fig 6.22).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangia with indusium, sporangial development gradate or mixed.
ORDER: POLYPODIALES
Sori abaxial, elongate, adjacent and parallel to the segment axis; sporangia stalked, annulus vertical; spores monolete.
FAMILY: BLECHNACEAE
Leaves unipinnate, sporangia borne on vascular commissures adjacent to midrib as coenosori.
GENUS: BLECHNUM
15. Lindsaea:
Plant Body (Sporophyte):
The plant is terrestrial with short creeping stem. Stem surface is covered with scales, stiff trichomus fibrous roots. Leaves are monomorphic and borne in a cluster. Lamina are simple with free to somewhat anastomosing veins.
Reproductive Structure:
Sporangium:
Sporangia are grouped as sori. Sori are marginal, laterally elongated, 1-2 nerved and borne on a vascular commissure connecting the vein ends. Sori are non-paraphysate and covered by an abaxial indusium.
Spore:
Spores are trilete, spheroidal with smooth to granulate surface (Fig 6.23).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plant homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the pinnae, sporangium with indusium.
ORDER: POLYPODIALES
Stem with trichome, sori indusiate.
FAMILY: DENNSTAEDTIACEAE
Indusium abaxial, spore trilete with smooth to granulate surface.
TRIBE: LINDSAEEAE
Lamina entire sori 1-2 nerved, laterally elongated, indusiate.
GENUS: LYNDSAEA
16. Cheilanthes:
Plant Body (Sporophyte):
The plant is terrestrial with long creeping and slender stem bearing scales and fibrous roots. Leaves are monomorphic, lamina 1 – pinnate, farinaceous and veins free. Margin of the fertile leaf segment is modified as an indusium.
Reproductive Structure:
Sporangium:
Few sporangia together often grouped as sori, which lies on leaf margin at vein tips. It is not paraphysate and ex-indusiate.
Spore:
Spores are globose to tetrahedral-globose and surface reticulate, cristate or verrucose type. (Fig 6.24).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root; leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangium in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem with scales, sori ex-indusiate.
FAMILY: PTERIDACEAE
Stem with scales, sori marginal at the apex of the vein tips, non paraphysate, and spore surface ornamented.
TRIBE: CIIEILANTHEAE
Spore surface cristate, reticulate or verrucose.
GENUS: CHEILANTHES
17. Pteris:
Plant Body (Sporophyte):
The plant body bears long-creeping rhizomatous stem bearing scales and few to many, usually long, fibrous roots. Leaves are periptnnate and borne in a cluster. Pinnae have free veins. A T.S. through rhizomatous stem shows central siphonostelic core with parenchymatous cortex.
Reproductive Structure:
Sori are marginal or sub-marginal, continuous as coenosori borne on vascular commissures connected with vein ends, being protected by reflexed leaf margin.
Sporangium:
Each sporangium is stalked. Mature and young sporangia are mixed together. Annulus is obliquely placed.
Spore:
It is tetrahedral, trilete and with coarsely reticulate surface. (Fig 6.25).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangia with indusium, sporangial development mixed.
ORDER: POLYPODIALES
Stem surface covered with scales; sori devoid of true indusium, sori protected by leaf margin; sporangia stalked, annulus vertical, homosporus, spore trilete.
FAMILY PTERIDACEAE
Sori develop on marginal commissure; margin of the fertile segment modified as indusium; sporangia contiguous in compact groups.
TRIBE: PTERIDAE
Leaves un-pinnate, pinnae long with marginal sori, sori without true indusium, annulus oblique; spores tetrahedral, trilete, surface reticulate.
GENUS: PTERIS
18. Polystichum:
Plant Body (Sporophyte):
The plant is terrestrial with small, stoat and erect stem including the persistent petiole bases, scales and fibrous roots. Leaves are monomorphic with the apical fertile portion somewhat contracted. Lamina are pinnatifid, 1-pinnate and with free veins.
Reproductive Structure:
Sporangium:
Sporangia are grouped together as sori. Sori are rounded and borne on the veins on a nearly flat receptacle. The sori are non-paraphysate and covered by a peltate persistent indusium. Sori are located in one row on each side of costa.
Spore:
Spores are ellipsoidal to somewhat spheroidal, monolete and surface more or less spinulose. (Fig 6.26).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root; sporangia aggregate on the leaf margin as sori, leaf megaphyllous.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem with scales, spores monlete, pinna stalk continuous with the rachis.
FAMILY: DRYOPTERIDACEAE
Leaves monomorphic, veins free.
TRIBE: DRYOPTERIDEAE
Lamina 1 – pinnate, indusium peltate and persistent, sori in one row on each side of the costa.
GENUS: POLYSTICHUM
19. Oleandra:
Plant Body (Sporophyte):
The plant is terrestrial with erect branching stem. Stem is slender, bearing scales and long rhizoids, leaves are monomorphic, entire, glabrate, and with free veins.
Reproductive Structure:
Sporangium:
Sporangia are grouped together as sori. Sori are roundish and borne on the veins. Sori are non-paraphysate, and covered by a reniform or orbicular indusium with a deep sinus.
Spore:
Spores are spheroidal, monolete with prominent wing-like fold on surface (Fig 6.27).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root; leaf megaphyllous, sporangia aggregates on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf, 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem with distinct scales, spore monolete, pinna stalks continuous with the rachis.
FAMILY: DRYOPTERIDACEAE
Sporangia borne on indusiate sori.
TRIBE: OLEANDREAE
Leaves monomorphic, indusium superior, lamina entire.
GENUS: OLEANDRA
20. Dryopteris:
Plant Body (Sporophyte):
The plant has creeping rhizomatous stem with scales and long roots. Mature stem portion bears persistem leaf bases. Leaves (fronds) are monomorphic and borne in a cluster. Lamina is unipinnate and glabrous with free veins. The lower portion of rachis is paleaceous, i.e., covered by numerous brown scales called ramenta. Younger leaves show circinate vernation.
T.S. of rhizome shows a simple dictyostelic vascular cylinder having a number of meristeles and leaf gaps.
Reproductive Structure:
Sporangium:
Sporangia are grouped together to form sori. They are roundish and borne on the veins on the baxial surface with a flat to slightly raised receptacle covered by a usually reniform indusium. They lie in between the midrib and the margin. The sporangia are mixed, stalked and each possesses a vertical annulus with stomium at one side.
Spores:
Spores are ellipsoidal, monolete, surface slightly regulose to spinulose (Fig 6.28).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangia with indusium, sporangial development mixed.
ORDER: POLYPODIALES
Stem erect, creeping to scandent, with scales; Leaves pinnate, sori on veins, indusiate, indusium reniform, annulus vertical, homosporous, spore monolete and spheroidal.
FAMILY: DRYOPTERIDACEAE
Stem creeping, leaves monomorphic, pinnae mostly non-articulate.
TRIBE: DRYOPTERIDAE
Veins free, Lamina unipinnate, sorus indusiate, indusium reniform.
GENUS: DRYOPTERIS
21. Vittaria:
Plant Body (Sporophyte):
The plants are epiphytic and stem is short, creeping, small, bearing scales and a few spongy roots. Leaves are monomorphic, mostly borne in a cluster. Lamina is entire, linear and veins are anastomosing without included free veinlets. Sori are located near the margin of lamina.
Reproductive Structure:
Sporangium:
Sporangia are grouped together as sori and sori are more or less sunken and long sorus extends along the margins of the lamina. Sporangia are located on the veins. Sporangia and paraphyses are grouped together in each sori. Paraphyses are branched with- an enlarged apical cell. Sori are ex-indusiate.
Spore:
Spores are tetrahedral – globose, trilete and surface papillate (Fig 6.29).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem short and covered with scales, lamina entire, indusium absent.
FAMILY: VITTARIACEAE
Veins anastomosing, sori sunken and very long near each margin, paraphyses with an enlarged apex.
GENUS: VITTARIA
22. Diplazium:
Plant Body (Sporophyte):
The plant is terrestrial with short erect stem bearing scales and fibrous roots. Leaves are monomorphic, with pinnatifid lamina. Veins are anastomosing with elongated sori borne on the veins.
Reproductive Structure:
Sporangium:
Sporangia are grouped together into distinct elongated sori. Sori are indusiate and non-paraphysate.
Spore:
Spores are ellipsoidal, monolete with prominent wing-like folds on surface (Fig. 6.30).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root; leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem with distinct scales, spore monolete, pinna stalks continuous with the rachis.
FAMILY: DRYOPTERIDACEAE
Leaves monomorphic, lamina 1 – pinnate, veins anastomosing, sori branched with the veins.
TRIBE: PHYSEMATIEAE
Sori elongated and indusiate, spores with prominent wing-like fold.
GENUS: DIPLAZIUM
23. Athyrium:
Plant Body (Sporophyte):
The plant has nearly erected to decumbent stem with scaly covering and fibrous soft roots. Leaves are monomorphic, and borne as loose clusters on the stem. Lamina is unipinnate – pinnatifid, more or less glabrous. Veins are free; sori lie on one side of veins. T.S. through stem shows dictyostelic condition. The section of petiole shows two vascular bundles, which are conspicuous at the base.
Reproductive Structure:
Sporangium:
Sporangia are aggregated to form sorus. Each sorus is covered by reniform to somewhat elongate indusium. Sporangia are mixed, stalked and devoid of paraphysis. Annulus is vertical in position.
Spore:
It is ellipsoidal, monolete, and surface is rugose (Fig 6.31).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1 – 2 pinnate, sporangia in sori on the vental side of the leaf, sporangia with indusium, sporangial development mixed.
ORDER: POLYPODIALES
Sporangia borne in roundish to elongate linear, abaxial sori, or rarely also on the leaf tissue, indusiate, indusium reniform, sporangia stalked, annulus vertical.
FAMILY: DRYOPTERIDACEAE
Two vascular bundles in the petiole.
TRIBE: PHYSEMATIEAE
Leaves monomorphic; sporangia in sori, indusiate, on the side of a vein, spores usually with coarse, rugose folds.
GENUS: ATHYRIUM
24. Pteridium:
Plant Body (Sporophyte):
The plant is terrestrial with long creeping stem. Stem bears trichomes and a few fibrous roots. Leaves are monomorphic; lamina is 2 – pinnate to 4 – pinnate. Veins are free.
Reproductive Structure:
Sporangium:
Sporangia are grouped as sori. Sori are marginal to the famine, lies on a vascular commissure between the apex and sinus of a segment. Sori are non paraphysate, but indusiate. Indusium is formed by the recurved modified margin of the fertile pinnae.
Spore:
Spores are tetrahedral – globose, with irregularly granulate surface. (Fig 6.32).
Identification:
Plant body differentiated into rhizomatous stem, root and leaf, leaf megaphyllous, sporangia aggregate on the leaf margin as sori.
CLASS: FILICOPSIDA
Plant homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangium with or without indusium.
ORDER: POLYPODIALES
Stem with trichomes, sori indusiate.
FAMILY: DENNSTAEDTIACEAE
Indusium formed by reflexed pinnae margin.
TRIBLE: DENNSTAEDTIEAE
Indusium of sori formed by recurved margin of fertile pinnae, sori few too many nerved.
GENUS: PTERIDIUM
25. Ceratopteris:
Plant Body (Sporophyte):
The plant body has a small, hard, stem with scales and roots. Leaves are dimorphic. The sterile leaves are 3 lobed. The fertile leaves are more erect, longer with narrower segments and 1 to 5 pinnate and borne in a cluster. Each leaf has veins anastomosing without included free veinlets.
The anatomy of the stem shows protostelic condition which later becomes dictyostelic.
Reproductive Structure:
Fertile fronds are large and dissected like a stag hom.
Sporangium:
It is solitary, sub-marginal and sub-sessile. The sporangial structure, specially the annulus, is very variable and the vertical annulus may be complete or incomplete and with or without a stomium. The margin of the fertile segment is modified as an indusium.
Spore:
It is homosporous, globose, trilete and ridged. (Fig 6.33).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plants homosporous, leaf 1-2 pinnate, sporangia in sori on the ventral side of the leaf, sporangia with indusium, sporangial development mixed.
ORDER: POLYPODIALES
Spores homosporous, trilete, sori indusiate, marginal; leaf dimorphic.
FAMILY: PTERIDACEAE
Sporangia distant on the veins, often with few annulus cells, spores large and strongly ridged.
TRIBE: CERATOPTERIDEAE
Margin of the fertile segment modified as an indusium, sporangia distant on the veins of the unipinnate fertile lamina.
GENUS: CERATOPTERIS
26. Marsilea:
Plant Body (Sporophyte):
The plant body has a creeping rhizomatous stem with nodes and fairly long internodes. Adventitious, branched roots develop in clusters from below the nodes.
The rhizome branches freely and the branches produce leaves. A mature leaf shows a long petiole on the tip of which there are four leaflets. The venation of the triangular leaflets is dichotomous but the fine veins anastomose at the apices. The leaflet margin is entire, serrate to crenulate.
A. T.S. of stem shows a single layer of epidermis, outer and inner cortex. The outer cortex shows a ring of large air spaces interspersed with only single rows of cells. The inner cortex bears outer sclerenchymatous layer and inner parenchymatous layer. The cortex is internally lined by endodermis. The stele is surrounded by pericycle. The stele is amphiphloic siphonostelic. There is distinct pith. Xylem is exarch (Fig 6.34).
Reproductive Structure:
Sporocarp:
There are oval, bean-shaped rounded to squarish and usually formed in a cluster of a few to many; A longitudinal horizontal section of the sporocarp cuts each sorus transversely and it is seen that each sorus is elongate, covered by a delicate indusium, gradade basipetal in arrangement with a row of larger sporangia (mega-sporangia) on top and two rows of smaller sporangia (microsporangia) on two sides. Mucilage rings are present at the two ends.
Spore:
It is heterosporous. Sporangia are of two types — mega-sporangium bears single, ellipsoidal megaspore with an apical papilla like laesura and papillate surface; microsporangium bears many small, spheroidal, trilete microspores with rugulose surface. (Fig 6.35).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Stem creeping, slender, often branched, and rooted in the soil; leaf petiolate, sori borne within sporocarp, indusiate, heterosporous.
ORDER: MARSILEALES
Leaflet veins dichotomous, anastomosing at the tips, sporocarp hard, flat, and stalked, sori gradade.
FAMILY: MARSILEACEAE
Leaflets at the apex of the petiole, leaflets 4 in number.
GENUS: MARSILEA
27. Salvinia:
Plant Body (Sporophyte):
The plant body is rootless, branched and possesses hairy rhizome. The rhizome is densely covered with leaves in alternate whorls of three thus giving rise to six rows of leaves. At each node two rows of leaves are lateral and floating and the third row is submerged.
Submerged leaf is modified into numerous root-like filaments with multicellular hairs. Leaves are entire, ovate, and oblong to sub-orbicular. Each leaf has a midrib and anastomosing veins.
The upper surface of floating leaf is papillose to hairy. T.S. of the stem shows extreme reduction and has a single layered non-cuticularised epidermis, aerenchymatous cortex with large air spaces and siphonostelic central core surrounded by endodermis.
Reproductive Structure:
Sporocarp:
The sporocarps are globose to ovoid, hairy when young, and borne in clusters near the base of the submerged leaf. A section through sporocarp shows one kind of sporangia, either microsporangia with many microspores or, mega-sporangia with a few megaspores. Sporangium is enclosed by indusium.
Spore:
It is trilete, megaspore surface perforate, and microspore surface rugulose (Fig 6.36).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root, leaf megaphyllous, sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plant free floating, each sporocarp contains only one kind of sporangia (micro or mega-sporangia), heterosporous.
ORDER: SALVINIALES
Heterosporous, the leaf bearing mega-sporangia and microsporangia enclosed in small, specialized structure – sporocarp, floating leaves entire, oblong to sub-orbicular.
FAMILY: SALVINIACEAE
Leaves in whorls of three, two broad floating, with anastomosing veins, one submerged, branches root-like.
GENUS: SALVINIA
28. Azolla:
Plant Body (Sporophyte):
The plant body is thin, delicate and has pinnately branched rhizome with two rows of alternating leaves densely packed to overlap one another on the upper surface of rhizome. Long adventitious roots develop from lower surface of rhizome. Each leaf has two lobes.
Upper chlorophyll containing cellular lobe with palisade and stomata above and below a cavity containing endophytic alga, Anabaena azollae. Each leaf has a single vein. The lower submerged lobe is colourless and one cell in thickness. A T.S. through stem shows central siphonostelic core surrounded by endodermis, delicate cortex and epidermis.
Reproductive Structure:
Sporocarp:
Sporocarps are dimorphic, sporangia are borne in short stalked sori on the lower lobe and are enclosed by an indusium and so forming a sporocarp. Each sporocarp either contains one mega-sporangium (megasporocarp) or several microsporangiam (microsporocarp).
Spore:
Megaspore is tuberculated with a perforate surface, but microspore surface is smooth. Both kinds of spores are embedded in massulae (Fig 6.37).
Identification:
Plant body differentiated into rhizomatous stem, leaf and root; leaf megaphyllous; sporangia aggregate mostly on the leaf margin as sori.
CLASS: FILICOPSIDA
Plant free floating, each sporocarp contains only one kind of sporangia (micro or mega-sporangia), heterosporous.
ORDER: SALVINEALES
Plants distinctly delicate and small with two rows of leaves, densely packed in overlapping manner on rhizomatous stem.
FAMILY: AZOLLACEAE
Leaves alternate, bilobed, long; sporocarp dimorphic.
GENUS: AZOLLA