Comparitive account of spore bearing organ of lycopodium and selaginelle
Answers
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.