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Largest Ovule: The ovules of Cycas are the largest in the plant kingdom. The ovules of C.circinalis are about 6cm wide, whereas those of C.thouarsii are 7mm wide.

Largest Egg: The egg of Cycas is the largest among all living plants. It is about ½ mm in diameter in C.circinalis.

Largest Sperms: The sperms of Cycas revoluta are the largest in the plant kingdom and measure about 200 to 300µ wide. They are top-shaped, multiciliate with spiral band of cilia.

Sequoia sempervirens (found in Red wood park of California) which measures about 368.5 ft in height is the world’s tallest gymnosperm tree.

Sequodendron is the largest gymnosperm tree (in girth). Its trunk measures about 13-16 metres in diameter.

Apospory: Formation of gametophyte differently from sporophyte without meiotic production of spores. Such gametophytes are generally diploid. Apospory was  discovered by Druery (1884) in fern Athyrium.

Apogamy: Formation of sporophyte differently from gametophyte without formation and fusion of gametes. Such sporophytes are normally haploid and non-functional. However, where gametophyte is diploid, it survives. Apogamy was discovered by Farlow(1874) in fern Pteris cretica.

Mr. A. KINGSLIN M.Sc, BEd, Phd,(doing)
Post Graduate Teacher in Botany
St. Mary Goretty Hr. Sec School, Manalikarai 
Kanyakumari district

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