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Learn about the comparison of Cycas and Pinus.
Cycas:
1. A small palm-like tree.
2. Plant body differentiated into root, stem and leaves; the roots are of two types- normal and coralloid.
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3. In the beginning the stem is tuberous, later on becomes columnar, un-branched and covered with persistent leaf bases.
4. Leaves large and compound with circinate vernation; leaf crown on the top of the plant.
5. Xylem consists of tracheids; companion cells absent from phloem; secondary xylem tracheids do not possess spiral thickenings.
6. No resin canals; mucilage canals present in the mesophyll tissue.
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7. Root stele diarch to tetrarch.
8. Girdle traces present in the cortex of stem.
9. During secondary growth several successive rings of cambium are formed; the primary cambium is short lived; secondary cambium rings form concentric zones of xylem; no annual rings.
10. Mesophyll tissue differentiated into palisade and spongy tissue; no peg-like infolding’s; xylem mesarch in the midrib.
11. Transfusion tissue well developed in the leaves.
12. Vegetative reproduction by buds or bulbils.
13. Plants usually dioecious; cones simple and unisexual.
14. Sporophylls differ from foliage leaves, arranged in cones, i.e., male and female cones..
15. Microsporophyll triangular, woody, not peltate bearing numerous microsporangia.
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16. Male cone terminal, large bearing numerous microsporophylls.
17. Microspores (pollen) not winged.
18. Female cone has a whorl of loosely arranged megasporophylls.
19. Each megasporophyll quite large in size, bearing 1-5 pairs of big ovules.
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20. Ovule bears 1-2 integuments.
21. One megaspore (embryosac) in each megasporangium (ovule).
22. A sharp nucellar beak and a pollen chamber.
23. Nucellus free in the upper part or through out and not fused with the integument.
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24. At the time of fertilization the embryo sac consists of a gametophyte having many food laden cells and 2-3 archegonia.
25. 3-celled pollen are shed from the pollen sacs and pollinated by wind. Pollen grains are caught in the mucilage drop oozing out from the micropyle. As the drop dries the pollen are taken back into the pollen chambers.
26. Pollen deposited directly on the nucellus during pollination; further development of pollen is completed in pollen chamber.
27. Microspore germinates in situ (within microsporangium) while the germination is completed on the nucellus after pollination.
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28. The microspore cuts off only one prothallus cell, which is persistent (male gametophyte).
29. Generative cell produces two male gametes while large vegetative cell gives rise to tube cell and stalk cell.
30. The male gametes are large and multiflagellate.
31. The motile sperms move in the pollen tube and reach the neck of the archegonium; here the pollen tube acts as haustorium.
32. The female gametophyte is formed by the free nuclear di\i- on of the nuclear embryo sac cell; wall formation starts when numerous (1000) nuclei nave been formed within the megaspore
33. The megaspore germinates inside the megasporangium (ovule).
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34 Female gametophyte bears 3-6 archegonia per ovule; neck present; no ventral canal cell: ventral nucleus present.
35. Female gametophyte parasitic on nucellus.
36. The end of pollen tube bursts, discharges antherozoids in archegonial chamber where they swim and approach the archegonial necks; a spermatozoid enters the neck of archegonium; the male nucleus fuses with the egg nucleus resulting in the formation of oospore.
37. Endosperm develops from the vegetative parts of the female gametophyte, before fertilization; it is haploid.
38. The oospore divides by free nuclear division and the wall formation starts when numerous nuclei are formed.
39. Proembryo has no clear tiers.
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40. Only one embryo is formed; no cleavage polyembryony.
41. Seed has no perisperm; two cotyledons; testa fleshy and coloured; aril absent; endospermic.
42. Seeds have no wings.
43. Hypogeal germination of seed.
Pinus:
1. A tall, branched tree.
2. Plant body differentiated into root, stem and leaves; tap roots and mycorrhizic roots.
3. Stem cylindrical, branched; the branches are of two types, i. e, branches of limited growth (dwarf shots) and branches of unlimited growth (long shoots).
4. Leaves needle-like and grow on dwarf shoots; no circinate vernation.
5. As in Cycas.
6. Resin canals present; no mucilage canals.
7. Root stele diarch to hexarch.
8. Girdle traces absent.
9. Secondary growth; the cambium ring is persistent and produces a continuous cylinder of secondary xylem; annual rings are formed.
10. Mesophyll not differentiated into palisade and spongy tissue; mesophyll cells have peg-like infoldings; two vascular bundles with endarch xylem.
11. Transfusion tissue less developed.
12. No vegetative reproduction.
13. Plants usually monoecious; cones simple and unisexual.
14. Sporophylls arranged in male and female cones.
15. Microsporophyll scaly, not peltate, bearing two microsporangia.
16. Male cones small, grouped in clusters replace the dwarf shoot and not ma
17. Microspores (pollen) winged exine inflated to form balloon-like expans
18. Female cone compact and corresponds to an inflorescence; ovuliferous scale represents female flower.
19. Each megasporophyll or carpel is quite simple; each ovuliferous scale bears two ovules on its upper surface near the central axis.
20. Ovule bears single integument.
21. As in Cycas.
22. Pollen chamber and nucellar beak absent.
23. As in Cycas.
24. At the time of fertilization the embryosac consists of a gametophyte having many food laden cells bearing 2-3 archegonia.
25. Wind pollination; pollen grains enter the open ovuliferous scale and get entangled in the oozing mucilage drop from micropyle.
26. As in Cycas.
27. As in Cycas.
28. The microspore cuts off two prothallial cells towards the pointed end (male gametophyte).
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29. As in Cycas.
30. Male gametes small non-motile.
31. The non-motile sperms are carried to the mouth of archegonia through pollen tube; pollen tube acts as sperms carrier and haustorium.
32. As in Cycas.
33. As in Cycas.
34. Female gametophyte bears one or two archegonia; no neck canal cell.
35. As in Cycas.
36. Usually a time interval of one year in between pollination and fertilization; fertilization occurs in the end of April; pollen tube reaches the neck of archegonium; the neck breaks and receives the contents from pollen tube; male nucleus fuses with the egg nucleus forming oospore.
37. As in Cycas.
38. Wall formation starts when eight-nucleate stage is attained.
39. Proembryo has four distinct tiers.
40. Four potential embryos, but only one matures; common occurrence of-cleavage polyembryony.
41. Perisperm present; numerous cotyledons in each seed; no aril; testa dry; endospermic.
42. Seeds winged.
43. Epigeal germination of seed.
