Pondweed Family 11 



** With submerged leaves only. 



3. P. foliosus Californicus Morong. Stems 0.3-1 m. long, mucli 

 branched, flattened or winged; leaves 3-5 cm. long, 2 mm. wide, 

 3-nerved or sometimes 5-nerved toward the base ; stipules free 

 from the leaves, small, white, becoming setose; peduncles 8-12 

 mm. long, erect, clavate, flattened; spikes subeapitate, 6-12-flow- 

 ered; fruit lenticular or nearly orbicular, about 2 mm. long, 3- 

 keeled on the back, middle keel winged, sinuate-dentate, face 

 strongly angled or arched; style apical. (P. paucijiorus Cali- 

 fornicus Morong.) 



Occasional in streams and irrigating ditches in our interior valleys. 

 June-September. 



4. P. pectinatus L. Stems 0.3-1 m. long, slender, mucb 

 branched, branches repeatedly forking; leaves setaceous, attenu- 

 ate to the apex, 1-nerved, often capillary and nerveless, 2-10 cm. 

 long; stipules half free, 1-2 cm. long, their sheaths scarious 

 on the margins; peduncles filiform, 4-10 cm. long; spike 1-4 cm. 

 long; flowers in whorls; fruit obliquely obovoid, about 4 mm. 

 long, with two ohscure lateral ridges on the back ; style straight, 

 or curved, facial. 



Common in streams and ponds. May-August. 



2. RUPPIA L. Ditch-grass. 



Stems capillary, widely branched. Leaves all sub- 

 merged very slender attenuate 1-nerved, with mem- 

 branous sheaths at the base. Flowers on a capillary 

 spadix-like peduncle naked perfect, consisting of 2 ses- 

 sile anthers, 2-celled. attached by the back to the 

 peduncle, having between them several pistillate flowers 

 with sessile peltate stigmas in 2 sets on opposite sides 

 of the rachis, the whole at first enclosed in the sheathing 

 base of the leaf ; in developmenl the peduncle elongates, 

 bearing the pistillate flowers at the end ; fertilization 

 takes place at the surface, after which the peduncle coils 

 up. Fruit a small obliquely pointed drupe, pedicelled. 



1. R. maritima L. Stems 0.5-1 m. long; leaves 4-6 cm. lonj: ; 

 sheaths membranous, G-8 mm. long; peduncles 4-20 cm. long or 



