250 



NAJADACEiE. 



Najas. 



CONSPECTUS OF THE GENERA. 



1. Najas. Flowers dioecious, mostly solitary, axillary, naked: the sterile consisting of a solitary stamen ; the fertile of 



a pistil containing a single ovule. Style short : stigmas 2 - 3 or rarely 4, subulate. 



2. Zostera. Flowers monoecious, naked, in two rows on a linear spadix. Style single : stigmas 2, 



3. Ruppia. Flowers perfect, 2 or several on a spadix, naked, with 4 stamens and 4 ovaries ; the latter at first sessile, 



but in fruit on long pedicels. 



4. Zannichellia. Flowers monoecious, naked, axillary: the sterile solitary, or consisting of a single stamen; the 



fertile 2-6 from a short cup-like sheath, nearly sessile : stigma peltate. 



5. Potamogeton. Flowers perfect, sessile, in spikes. Perianth of 4 scales. Stigma simple. Pistils 4, which become 



4 small nuts. 



1. NAJAS. Linn.; Kunth, ennm. 3. p. 111. WATER-NYMPH. 



[So named from the Latin, nais, a water nymph ; in allusion to its place of growth.] 



Flowers dioecious, naked ; the staminate reduced to a single stamen, each included in a 

 calyptriform spatha : anthers at first nearly sessile, but the filament is elongated after 

 flowering, either 4-celled and bursting at the summit by 4 revolute valves, or 1 - 2-celled : 

 pollen globose. Fertile flowers reduced to a single pistil, without a spatha. Ovary sessile : 

 ovule erect, anatropous : style short : stigmas 2-3, subulate. Fruit drupaceous, a little 

 nut enclosed in a loose epicarp, the shell crustaceous. Seed conformed to the nucule, 

 straight, the radicular extremity inferior. — Submersed aquatic herbs, with slender branching 

 stems, and ternate or opposite sessile leaves which are dilated and sheathing at the base. 

 Flowers axillary, mostly solitary, inconspicuous. 



1. Najas Canadensis, Michz. Canadian Water-nymph. 



Leaves narrowly linear, membranaceous, fasciculate in the axils, one-nerved, remotely and 

 minutely spinulose-denticulate or entire ; sheaths denticulate ; style unequally 4-cleft ; nut 

 elliptical-fusiform, thin and crustaceous. — Michx.fl. 2. p. 220 ; Pursh, fl. 2. p. 620 ; Hook, 

 fl. Bor.-Am. 2. p. 170. t. 184 ; Kunth, enum. 3. p. 115. Caulinia flexilis, Willd. in act. acad. 

 Berol. 1798, p. 89. t. 1./. 1 ; Pursh, I. c. 1. p. 2 ; Muhl. cat. p. 86 ; Torr. compend. p. 330 ; 

 Ell. sk. 2. p. 515 ; Beck, hot. p. 114; Kunth, I. c. (in part). 



Annual ? Stem 6-18 inches long, much branched in a dichotomous manner. Leaves 

 opposite, but appearing verticillate from the short leafy branches in the axils, half an inch to 

 an inch long and scarcely a line wide, marked with an indistinct midrib, the margin (particu- 

 larly towards the apex) very finely denticulate, spreading and more or less recurved. Sterile 

 flowers not seen. Fertile flowers sessile in the axils, solitary, but sometimes several approxi- 

 mated, lanceolate, tapering to the summit, and ending in 4 subulate unequal stigmas : ovule 

 arising from the base, sessile. Fruit apparently an utricle, containing a narrow smooth seed ; 

 but, according to most authors, the latter is a nucule, the endocarp of which has separated at 

 an early stage from the membranaceous epicarp : shell (testa ?) pale brown, slightly pointed 



