The upcoming discussion will update you about the difference among Gnetum, Ephedra and Welwitschia.
Difference # Gnetum
1. Distribution of gnetum in restricted to tropical or subtropical and humid regions of several countries of the world.
2. Habit of gnetum is most of the species are lianes or trees and only a few are shrubs and trees.
3. Leaves of gnetum are foliaceous, green and angio-sperms-like.
4. Venation of gnetum are reticulate and unicostate.
5. Stomatal Development of gnetum is syndetocheilic
6. Shoot Apex of gnetum follows an open system of growth with a definable tunica layer.
7. Compound strobili of gnetum are cauline and only very rarely terminal.
8. Male Gametophyte of gnetum are:
(i) Only a single prothallial cell is present in the male gametophyte.
(ii) No sterile cell and spermatogenous cell are formed in the young male gametophyte.
9. Female Gametophyte of gnetum are:
(i) Normal archegoraa are absent in the female gametophyte. A free nucleus organises some cytoplasmic material around itself and functions directly as an egg.
(ii) The upper portion of the female gametophyte remains free- nuclear at the time of fertilization and the lower portion becomes cellular.
10. Endosperm of gnetum is like angiosperms, the endosperm in Gnetum is formed after fertilization.
11. Fertilization of gnetum takes place in an embryo sac.
12. In gnetum there is no free-nuclear division phase in the embryogenesis.
13. Feeder in gnetum is present in the embryo.
14. Haploid Chromosome Number of gnetum is 22.
Difference # Ephedra:
1. Distribution if ephedra occurs in dry and arid regions of North and South America, and several countries of Old World including India and China.
2. Habit of ephedra is most of the species are bushy or shrubby and only a few are lianes.
3. Leaves of ephedra are small and scale-like.
4. Venation of ephedra is parallel.
5. Stomatal Development of ephedra is haplocheilic.
6. Shoot Apex of ephedra is same as in Gnetum.
7. Compound strobili of ephedra are terminal and never cauline.
8. Male Gametophyte of ephedra are:
(i) A pair of prothallial cells are present in the male gametophyte.
(ii) A sterile cell and a spermatogenous cell are formed in the male gametophyte.
9. Female Gametophyte of ephedra are:
(i) Normal archegonia are present in the female gametophyte.
(ii) Prior to fertilization, the entire female gametophyte becomes cellular.
10.In ephedra endosperm is not formed.
11.Fertilization in ephedra takes place in an archegonium.
12. Free-nuclear divisions take place in the zygote until about 8 nuclei are formed in ephedra.
13. Feeder is absent in ephedra.
14. Haploid Chromosome Number of ephedra is 7 or 14.
Difference # Wetwitschia:
1. Wetwitschia is distributed only in a narrow coastal belt of about 1000 km in south-west Africa.
2. Habit of wetwitschia is the only known species of this genus resembles a gigantic turnip.
3. Leaves of wetwitschia are only two, large, thick foliaceous, ribbon-like, persistent and attain a length of about two metres. .
4. Venation of wetwitschia are parallel veins are joined by transverse or interwoven veinlets
5. Stomatal Development of wetwitschia is syndetocheilic.
6. Shoot Apex of wetwitschia follows a closed system of growth where the shoot apex stops activity after initiating a pair of foliage-leaf primordia.
7. Compound strobili of wetwitschia are cauline and only very rarely terminal.
8. Male Gametophyte of wetwitschia are:
(i) Only a single prothallial cell is present in the male gametophyte.
(ii) No sterile cell and spermatogenous cell are formed in the young male gametophyte.
9. Female Gametophyte of wetwitschia are:
(i) Only archegonial initials are present. These function directly as eggs.
(ii) Prior to fertilization, the entire female gametophyte becomes cellular.
10. Endosperm is not present in of wetwitschia.
11. Fertilization of of wetwitschia takes place in the pollen tube which is not found in any gymnosperms or angiosperms. Same as in Gnetum.
12. There is no free-nuclear division phase in the embryogenesis in wetwitschia.
13. Feeder present in wetwitschia.
14. Haploid Chromosome Number of wetwitschia is 21.