Morphology of Cycus

1. A small palm-like tree.

2. Plant body differentiated into root, stem and leaves; the roots are of two types- normal and coralloid.

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.

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.

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.

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.

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.

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).

34 Female gametophyte bears 3-6 archegonia per ovule; neck present; no ventral canal cell: ventral nucleus present.

35. Female gametophyte parasitic on nucellus.

Morphology of Pinus tree