30 NAIADACEAE. 



Nutlet dull, reticulated; sheathing base of leaves commonly narrow and with few 

 teeth or sometimes entire 3. N. gitadahipensis. 



1. N. marina L. Holly-leaved Naiad. Stems stout, often armed with 

 prickles twice as long as their breadth; leaves linear, % to iy 2 i n - l° n g> 1 to 

 l 1 /^ lines broad, coarsely saw-toothed, with the teeth spinulose-tipped and 

 the broad sheathing base entire or with 1 or 2 teeth on each side; nutlet 2 to 

 2% lines long, reticulated. — (N. major All.) 



Clear Lake to Lower California and the Atlantic States. 



2. N. flexilis R. & S. Slender Naiad. Stems slender; leaves narrowly 

 linear, very minutely toothed, mostly acuminate, !/> to 1 in. long, % to y 2 line 

 wide; nutlet oblong-ovoid, 1 to 2 lines long, nearly smooth, shining. 



Southern California to Washington, eastward to the Atlantic and in Europe. 



3. N. guadalupensis (Spreng.) Morong. Stems thread-like, 1 to 2 ft. long; 

 leaves 6 to 9 lines long, % line wide or something less, abruptly acute; nutlet 

 cylindrical, 1 to 1% lines long, dull but distinctly marked with numerous rows 

 of squarish reticulations. 



Oregon to San Francisco and southeastward to the Atlantic. 



4. ZANNICHELLIA Mich. 



Immersed aquatic plants, flowering and fruiting under water, the thread-like 

 stems from a creeping rootstock. Leaves opposite or in whorls. Flowers monoe- 

 cious, without perianth, sessile, both kinds in the same axil: staminate flowers 

 consisting of an anther on a pedicel-like filament; pistillate flowers 2 to 6 

 in a cluster and surrounded by a hyaline cup-shaped involucre shorter than 

 the pistils, each flower consisting of a single pistil with a thin peltate stigma 

 on the summit of the short style. Fruit an oblong somewhat flattened, beaked 

 nutlet. (Zannichelli, 1662-1729, a botanist of Venice.) 



1. Z. palustris L. Horned Pondweed. Stems sparingly branched, 1 to 



1 ! •_. ft. long; leaves 1 to 2 in. long, filiform but flat; pistils usually 4, in fruit 

 slightly incurved, becoming stipulate, 1 to 1% lines long, often roughened or 

 toothed on the back. 



Pools and still waters of streams: Southern California to the Sacramento 

 Valley. Cosmopolitan. 



5. ZOSTERA L. Grass-wrack. 

 Submerged maritime herfts with elongated and very narrow grass-like radical 

 leaves and inflorescences raised on peduncle-like stems. Flowers monoecious, 

 borne in 2 rows on the face of a flattened spadix with or without small lateral 

 appendages covering them in the bud and closely invested by a protecting 

 foliaceous spathe until anthesis. staminate flower of 1 stamen. Pistillate 

 flower of 1 pistil. Nutlet ovoid. (Creek zoster, a girdle or band, on account of 

 the ribbon-like leaves.) 



1. Z. marina L. Eel-grass. Leaves with long sheathing bases, 3 to 

 7 aerved, l to l ft. long, 1 to I lines broad; fruiting Leaves jointed at base of 

 spathe, which terminates with a more or Less elongated Leaf-like summit; spadix 



2 to 4 in. long, 10 to 20 fruited; fruits L% lines long, the ribs of the seed 

 showing clearly on I he pericarp. 



Shoal waters of bays, San Pedro north to Alaska, Var. latifolia Morong. 

 Stem Btout, BOmetimes 8 or 10 ft. long; Leaves 3 to 6 lines wide; nutlet with a 

 distinct stipe, the pericarp splitting along the face. Santa Barbara north- 

 ward to Pugel Sound, ace. Morong (X. pacifies Wats.). 



