Zostem. NAIADACE.E. 



191 



• liiiiiiersed niiualics, with Hat linear leaves : ovaries solitary or (listiiict, 1-oviileil. — Naiadka;. 



4- Perianth none, or membranons and cni)-sliiiiic(l. 



+t Flowers monccuious or diuecious : ovary 1, sessile : stamen 1 (wliere known). 



1. Naias. Flowers diwcions, solitary or clustered, axillary. Pcriantli none in fertile flowers, 



cup-shaped and inenibranous in the staniinate. Style with 2 to 4 awl-shaped stigmas. 

 Stems floating, with opjiosito or ternate leaves. 



2. Zostera. Nakeil ovaries and stamens alternate in 2 vertical rows on the inner side of a mar- 



gined leaf-like enclosed si)adix ; ovaries pendulous. Stigmas 2, linear. Stem creeping. 



3. Phyllospadix. Ovaries naked, alternate in 2 rows on the inner side of a margined folia- 



ceously appendaged enclosed spadix, ascending. Stigmas 2, linear, sessile. 



4. Lileea. Fertile flowers in an cxserted slender spike. Stigma capitate. 



+ t +f Ovaries about 4, nearly sessile, becoming more or less stipitate. 



5. Zanuichellia. Flowers mon(ccious, axillary, sessile or nearly .so. Stamen 1, naked ; fila- 



ment slender. Fertile flowers solitary, with a cup-shaped membranous spathe or peri- 

 anth. Stigmas jieltate. Leaves opfiositc. 



6. Ruppia. Flowers perfect, 2 or more on an enclosed spadix, at length long-exserted, without 



perianth. Anthers 2, .sessile, the cells distinct. Stigma depressed. Leaves alternate. 

 +- +- Flowers perfect, with herbaceous 4-.sepaled perianth, in a peduncled spike. 



7. Potamogeton. Ovaries and anthers 4, ses.sile. Stigma sessile, unilateral. 



» » Marsh plants with terete bladeless leaves : flowers perfect, .spicato or racemose, with her- 

 baceous 6-lobed perianth : carpels 3 or ti, more or less united, separating at maturity : seed 

 erect or ascending, anatropous, with straight embryo. — Jun'OAGINK^e. 



8. Triglochin. Ovaries 3 to 6, united until maturity. Leaves radical. Flowers bractless, in 



a spike-like raceme terminating a jointless scape. 



9. Scheuchzeria. Ovaries 3, nearly distinct, at length divergent. Flowers bracteate in a 



loose raceme upon a leafy stem. 



1. NAIAS, Linn. Naiau. 

 Flowers mostly dioecious, a.xillary, solitary or clustered, sessile. Male flower of 

 a single stamen and a membranous tubular 4-lobed perianth within a small cup-shai)ed 

 membranous spathe ; anther 4-celled, nearly sessile : pollen granular. Fertile 

 flowers without perianth or spathe, the oblong ovary terminated by a short style and 

 2 to 4 narrowly subulate stigmas. Fruit a very thin membranous utricle, filled by 

 tlie single erect anatropous seed. Outer testa subcrustaceous. Embryo straight, 

 entire, with the minute plumule near the upper end. — Slender immersed aquatics, 

 with jointed brandling floating sterna, and opposite or verticillate (often crowded) 

 linear toothed leaves, sessile and somewhat dilated at base. 



Ten or twelve species are known, foiu- of which are found in the Atlantic States. 



1. N. major, AUione. Stem rather stout and often armed with broad prickles : 

 leaves broadly linear, 3 to 18 lines long, coarsely and sharply toothed, the dilated 

 ba.so entire : fruit 2 to 2^ linos long : seed very linely lineate, oblong, slightly com- 

 prcs.sed. — Noes, Gcmi. t. 44. 



In Clear Lake (liolnndrr) ; Huntington Valley, Nevada (Whrclcr); Santa Crnz T^iver, Arizona 

 {Dr. Smart); Utah, Purrii. It is also found in the salt springs of New York, in Kurope, the 

 West Indies, and the Sandwich Islands. 



2. N. flexilis, Rostk. Sc Schmidt. Stems very slender : leaves very narrowly 

 linear, a half to an inch long, very minutely serrulate : fruit 1^ lines long, narrowly 

 oblong. — N. Canadensis, Michx. ; Hook. Fl. Bor.-Am. ii. 170, t. 184. 



Near San Francisco (Chamis^n) ; Clear Lake (IMnndrr) ; Washington Territory {Lyall) ; com- 

 mon in the Atlantic States, and found in Mexico, the West Indies, and Euroj)e. 



2. ZOSTERA, Linn. KKL-t:itA.s.s. C.iiAss- whack. 



Flowers montKcious and without perianth, the single stamens and ovaries arranged 

 alternately in 2 rows upon the face of a linear-oblong leaf-like sessile spadix en- 



