122 Polygonaceae 



variously clustered. Pedicels jointed. Calyx 4-5-part- 

 ed, usually petaloid, the outer segments slightly larger 

 than the inner ones. Stamens 5-9 ; filaments glabrous ; 

 anthers oblong. Style 2-3-parted or 2-3-cleft ; stigmas 

 capitate. Achene lenticular or 3-angled, invested by 

 the persistent calyx. 



1. P. incarnatum Ell. Annual, glabrous or nearly so; stem 

 erect, simple or branched above, more or less swollen at the 

 nodes, 8-12 dm. high; leaves lanceolate, 6-18 cm. long, acumi- 

 nate at both ends, short petioled, sparingly punctate and ciliate; 

 sheaths loose, long, sometimes ciliate when young, becoming 

 naked; racemes panicled, drooping, 4-10 cm. long, linear; calyx 

 white or pink, small ; stamens 6 ; style 2-parted to near the base ; 

 achene ovoid-oblong, lenticular, smooth and shining. 



Marshes about Los Angeles. Probably introduced from the Atlantic 

 coast. 



2. P. lapathifolium L. Stem simple or much branched, 

 erect or ascending, swollen at the nodes, 3-12 dm. high, the 

 peduncles and petioles glandular; leaves lanceolate or oblong- 

 lanceolate, 5-20 cm. long, attenuate to the apex, tapering to the 

 short petiole, ciliate, inconspicuously punctate; sheath cylindric, 

 ribbed or striate; racemes panicled, 2.5-10 cm. long, drooping, 

 narrow, rather dense, calyx pink, white or greenish, 5-parted ; 

 stamens 6 ; style 2-parted to below the middle ; achene lenticular, 

 2 mm. long. (P. nodosum Pers.) 



Occasional along streams. 



3. P. hydropiperoides Michx. Stems rather stout, 3-10 dm. 

 high, erect or decumbent, clothed with short appressed hairs; 

 leaves lanceolate, obtuse; sheath cylindric, loose, ciliate; 

 racemes panicled, terminal, erect, narrow, more or less in- 

 terrupted, 3-7 cm. long; calyx white or whitish, often conspicu- 

 ous; stamens 8; style 3-parted to below the middle; achene 

 3-angled, ovoid or oblong, 2-2.5 mm. long, smooth. 



Frequent along streams, especially toward the coast. 



4. P. aviculare L. Annual or perennial, slender, glabrous, 

 bluish-green; stem prostrate or ascending, simple or much 

 branched, 1-6 dm. long; leaves linear to oblanceolate, commonly 

 oblong, 6-18 mm. long, nearly sessile ; sheath oblique, 2-parted 



