1) Mention the sifferences between gametophytes of Lycopodium and Equisetum.
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Comparison among Lycopodium, Selaginella and Equisetum | Pteridophyta
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Comparison Lycopodium:
(a) The Sporophyte:
1. Plants terrestrial herbs or epiphytes.
2. Stem is prosterate but the apex is upturned, densely covered with hairs, produces root branches.
3. Roots adventitious, produced from the older parts of the stem.
4. Leaves small, narrow, arranged densely and spirally on the stem, eligulate.
5. Sporophylls are similar to foliage leaves and aggregated at the tips of the branches forming strobilus.
6. Sporongia arises on the abaxial surface of the sporophylls or in their axils.
7. Spores all alike, numerous and small.
(b) The Gametophyte:
8. Spore is the first cell of the gametophyte. It produces prothallus on germination.
9. Gametophyte is of one kind and is represented by prothallus. It is small and round or tuberous, or carrot-like and infested by phycomycetous fungus.
10. Antheridium is embedded into the crown and surrounded by a jacket of sterile cells. It produces flagellate sperms.
11. Archegonium is embedded into the crown and is flask-shaped. It consists of six neck canal cells, one ventral canal cell and an egg cell.
12. No suspension.
Comparison # Selaginella:
(a) The Sporophyte:
1. Plants-delicate herbs.
2. Stem is creeping, apparently dichotomously branched, produces rhizophore at each bifurcation.
3. Roots adventitious, produced from the ends of the rhizophore.
4. Leaves are of two kinds in 4 ventrical rows – dorsal 2 rows are small, ventral 2 rows large, ligulate.
5. Sporophylls (both micro and mega) are spirally arranged at the tips of the lateral branches forming strobilus.
6. Sporangia (both micro and mega) arise in the axils of sporophyll (micro and mega).
7. Spores are of two kinds microspores and megaspores; microspores are small, numerous and are contained in the microsporangia, while the megaspores are large, 4, in number and contained in the 4 angled sporangia. Both are provided with tri-radiate ridge.
(b) The Gametophyte:
8. Spores are the first cells of the gametophytes. These produce two kinds of porthallimale. Prothallus and female prothalles.
9. Gametophytes are of two kinds. Male gametophyte is represented by the prothallial cell, and the female gametophyte by the mass of exposed green cells of the megaspores.
10. Antheridium is rudimentary end surrounded by a jacket of sterile cells. It produces biflagellate sperms.
11. Archegonium is produced on the female prothallus. Its structure is the same as that of Lycopodium.
12. Presence of suspensor.
Comparison # Equisetum:
(a) The Sporophyte:
1. Plants-usually perennial herb.
2. Stem is rhizome with nodes and internodes, produces two kinds of shoots – sterile and fertile, the sterile shoot is much branched and green while the fertile one is un-branched and non-green; item ribbel.
3. Roots adventitious, produced from the nodes of the rhizome.
4. Leaves small, scale like, fused to form a short sheath round the erect stems at the nodes.
5. Sporophylls are not be of like but consld of sporangiophores which are arranged in compact whorls at right angles to the fertile shoot forming the strobilus.
6. Sporahgia hanging from the corners of the peltate disc of the sporangiophores.
7. Spores all alike, numerous, small green and provided with elaters.
(b) The Gametophyte:
8. Spore is the first cell of the gametophyte. It produces one or two kinds of prothallus.
9. Gametophyte is of one or two kinds. In the latter case the male gametophyte is smaller than that of female one.
10. Antheridium is round and produces multi-flagellate sperms.
11. Archegonium is situated at the lips or margins of female prothallus. It is flask-shaped and consists of one or two neck canal cells, one ventral canal cell and one egg cell.