100 



NAIADACEJE. 



submerged leaves very thin, lanceolate, 4 to 12 in. long, rounded at 

 base or tapering into a petiole 1 to 4 in. long; stipules 1 to 4 in. long; 

 peduncles 2 to 3 in. long; spikes 1 to 2 in. long, densely fruited; 

 nutlets obliquely obovate, If to 2 lines long. 



Streams: Russian River southward to Santa Cruz; Sierra Nevada. 



2. P. lucens L. Stem branching below and often with masses of 

 short leafy branches at summit; leaves all submerged, thin, elliptical 

 to lanceolate or oblanceolate or the uppermost oval, many-nerved, 

 acute or acuminate, mucronate, often undulate-serrate, narrowed at 

 base to a short petiole or sessile, 2 to 7 in. long and f to If in. wide; 

 nerves 13 or fewer; stipules loose and spreading, sometimes very 

 broad; peduncles 3 to 6 in. long; spikes 2 to 2£ in. long, very thick 

 cylindrical; nutlet 1^ lines long, nearly as broad. 



San Francisco Peninsula. 



3. P. pauciflorus Pursh. Stems flattened, much branched, 1 to 

 3 ft. long; leaves all submerged, narrowly linear, 3-nerved or the 

 nerves obscure, 1 to 2 in. long, J to 1 line wide, narrowed at base; 

 stipules small, white, becoming setose; peduncles more or less clavate, 

 about £ in. long; spike subcapitate, few-flowered; nutlet 1 line long, 

 roundish or obliquely obovate, with a broad more or less undulate- 

 dentate keel. 



Still waters; near the coast. 



4. P. pusillus L. Stems filiform, branching, £ to 1 ft. long; 

 leaves all submerged, narrowly linear or often nearly setaceous, 

 obtuse and mucronate or acute at apex, 1 to 3-nerved, with 2 glands 

 at base or rarely glandless, 1 to 3 in. long, ^ to f line wide, sessile; 

 stipules obtuse, becoming setose; peduncles flattened, slender, £ to 3 

 in. long; spikes interrupted or capitate; nutlet obliquely elliptical, f 

 to 1 line long, curved and 2-grooved on the back, or sometimes with 

 3 distinct keels, beaked by a short style. 



Pools and ditches. - Coast Ranges. 



5. P. pectinatus L. Stems slender from a running rootstock, the 

 branches repeatedly forking, 1 to 3 ft. long; leaves capillary or 

 setaceous, often 1-nerved, 1 to 6 in. long; stipules \ to 1 in. long, free 

 for half their length; peduncles filiform, 2 to 12 in. long; flowers in 

 distinct whorls on a spike \ to 2 in. long; nutlets roundish or 

 obliquely obovate, \\ to 2 lines long, no middle keel on the back but 

 with obscure lateral ridges. 



Brackish water of tide sloughs or in ponds. 



2. RUPPIA L. Ditch-grass. 

 Immersed aquatic herbs with long filiform forking stems. Leaves 

 almost capillary, with a rather broad sheathing base. Peduncle of 

 the spadix axillary, at first very short and enclosed in the sheathing 

 spathe-like base of the leaf. Spadices slender, each with two flowers 

 disposed near together, rising to the surface when in anthesis. 

 Flowers perfect, entirely destitute of perianth. Stamens 2, sessile, 

 each anther consisting of 2 large and separate anther-cells. Pistils 



