364 Class XXII. Order II. 



DICECIA. 



DMJVDRM. 



422. VALLISNERIA, 

 VALLISNERIA AMERICANA. MX. V allisneria. 



Leaves linear ; stalks of the barren and fertile flow- 

 ers straight. 



The long, linear, obtuse leaves of this plant are found at the 

 bottom of stagnant waters stretching upward toward the surface. 

 I have not seen it in flower, but have repeatedly collected what, 

 I have no doubt, are the leaves. In the European plant, of 

 which this appears to be a cospecies, or variety, the fertile 

 flowers float on the surface, being connected with the root by 

 spiral stalks. The barren flowers grow near the bottom, but 

 break off, and rise to the surface before shedding their pollen. 

 In Fresh pond, Cambridge. 



423. SALIX. 

 SALIX ERIOCEPHALA. Mich. Swamp Willow. 



Diandrous ; twigs downy ; leaves oblong-oval, some- 

 what retuse at base, serrulate ; aments oval, exceeding- 

 ly villous. Mich. 



A small tree, common in low, moist grounds, where its woolly 

 aments expand during the month of March, and are usually in 

 flower the first week in April. The scales of both the barren 

 and fertile aments are covered with very long, even, smooth, 

 silken hairs, which at a distance give them a woolly appearance. 

 In the barren aments each scale produces two long, yellow an- 

 thers ; in the fertile ones, which exceed the last in length, they 

 support an oblong, tapering, downy germ. Leaves oval-oblong, 

 nearly entire, green above, glaucous and somewhat downy be- 

 neath. Stipules half cordate, deciduous. 



SALIX DISCOLOR. Willd. Bog Willow. 



Leaves oblong, rather obtuse, smooth, remotely ser- 

 rate, entire at the end, glaucous underneath ; stipules 

 deciduous, lanceolate, serrate ; aments nearly cotem- 

 porary, diandrous, oblong, downy, the scales oblong, 



