MICROSPERME.E 283 



formation, in waters relatively rich in mineral salts, 

 in stagnant waters and in slowly flowing waters in 

 the submerged-leaf association. 



The name Elodea implies that it is a marsh plant, 

 but it is really aquatic. In the older name Anacharis 

 the somewhat inelegant character is suggested, 

 unless it refer to the fact that the flowers rise up to 

 the surface. The second Babingtonian name Alsi- 

 nastrum indicates its resemblance to Alsine or Sea 

 Sandwort. The English name Water-thyme also 

 refers to the habitat of the plant. 



In colour the plant is dark green and the texture 

 is membranous, transparent. It is submerged. The 

 stems are solid, round in section, branched irregularly 

 and at intervals, semi-transparent, brittle, rooting at 

 the nodes. The plant is but slightly attached by the 

 membranous, long, threadlike roots. The leaves are 

 in whorls, three to four in a whorl, stalkless, blunt or 

 acute, bordered, linear to oblong, with small close 

 teeth, which point forwards, membranous, trans- 

 parent, with a minute, terminal point. The upper 

 leaves are not so acute as those below. They are 

 spreading at right angles. 



The stalkless, solitary, female flowers spring from 

 the axils of the upper leaves. Male flowers have only 

 been found near Edinburgh. The male flowers have 

 a perianth with six segments and nine stamens. 

 The male flower breaks off like a bud, and floats to 

 the surface, as in Vallisneria, when it opens. In the 

 greenish-purple female flowers the tube of the peri- 



