8. SALVmiACE.E. 

 Order HYDROFTERIDE^. Water-ferns. 



FAM. 8. SALYINIACE^. 



!Sma]l or delicate, mostly annual, aquatics floating on the surface 

 of the water with a dorsiventral stem with two or more rows of leaves, 

 sometimes verticillate, on the dorsal face, and modified filamentous 

 root-like leaves or true roots on the ventral face. Leaves folded 

 lengthwise in vernation. Sorus one in each unilocular thin-walled 

 sporocarp or indusium, which is composed of tAvo layers of cells. 

 Spores of two kinds, macrospores and microspores, those in the sporo- 

 carp all of one Idnd, but macrosporangia and microsporangia in the 

 same cluster on metamorphosed leaf -segments. Microspores giving 

 rise to a rudimentary prothallus which emerges from the spore through 

 a 3-cleft orifice and forming antheridia. Fem. prothallus well- 

 developed, emerging and bearing several archegonia. 



Leaves very small, 2-ranked, deeply 2-lobed. Roots present . . 1. Azolla. 



Leaves in numerous alternating 3-merous whorls, 2 aerial and one 

 ventral root-like submerged in each whorl. Aerial leaves in 4, sub- 

 merged in 2 alternating series on the stem. No true roots . , 2. Salvinia 



1. AZOLLA, Schreh. 



Small annual floating herbs with much dichotomously branched 

 stems, closely covered with minute fleshy imbricating leaves. L. 

 alternating in two series, deeply 2-lobed, lobes unec^ually developed, 

 upper floating with a peculiar recess on its inner side Avhich contains 

 Nostoc filaments, lower lobes submerged. Roots solitary or in tufts. 

 Sorus or sporocarp a 1 -celled capsule, wall or indusium 2 cells thick, 

 capsules 2 or 4 together on the lower lobe of the first lea.f of a lateral 

 shoot, containing either microsporangia or macrosporangia. Micro- 

 sporangia on a stalk of 2 cell-rows radiating from a slender columella, 

 containing numerous spores aggregated into " masulse " covered by 

 a hyaline cuticle. Macrosporangia with a single spore, the episporium 

 variously developed and furnished Avith swimming-bladders. 



1. A. pinnata, R. Br. Syn. Salvinia imbricata, Roxh. 



A small pretty floating aquatic, usually reddish especially towards 

 the end of the rainy season, with very small imbricate rhomboid 

 obtuse upper leaf-lobes. Roots solitary. Sori paired. Masulse 

 without glochidia. Macrospores with 9 swimming-bladders. 



Common in the r.s. and then disappearing ! Probably in all districts. 



The repeated dichotomous branching with the stronger branches alternately 

 to right and left results in a more or less deltoid form to the whole plant which 

 attains about l-Vb" diam. at the base. The upper leaf-lobes are sometimes 

 somewhat oblong, obtuse, papillose ; lower membranous, of but one layer of cells. 

 The roots have a distinct membranous root cap. 



2. SALVINIA, L. 



Small floating aquatics. Leaves in numerous 3-merous alternating 

 whorls consisting of two normal aerial dorsal leaves and the third 

 ventral submerged root-like, forming on the stem 4 rows of aerial 



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