Salvinia
(named in honour of Antonio Maria Salvini, a Professor at Florence in the seventeenth century). ORD. Salvinieae. A small genus (all the supposed species are reducible to one) of plants found floating on still water (like Lemna), broadly dispersed over the Northern hemisphere, and in tropical and South America. "This pretty little floating aquatic, which, like Azolla, is suitable for a stove, greenhouse, or indoor aquarium, is easily managed in the summer time, simply requiring to be let alone or have its water changed, if necessary; but in the winter is often lost through a want of knowledge of its life-history. The mature plant floats on the water, and has no true roots, though the row of divided leaves on the under side of the stem look like roots at first sight, and assume their functions. Among these the spore capsules are developed, and from them the plant must be grown annually, as the old plants die in the winter. The best way to preserve the spores is to half fill a broad pan with sandy loam, and then fill up with water; when the water has cleared, place a number of plants upon it, and stand the pan by in a cool greenhouse. In the winter, the plants will all die, but the spores will remain in the loam, which must not be thrown away or allowed to dry, and the next spring they will reproduce the plant" (N. E. Brown).
S. natans (floating). fr. consisting of globular bags, composed of a double membrane, at length bursting irregularly. l. Fern-like, sub-elliptic, entire, floating, not curled up when young. Rhizome floating, thread-like, leafy above, and furnished below with long rootlets and fruit on short, leafless branches. The young plant closely resembles a young Selaginella, apart from the two cotyledon-like processes.