62 Flora of the Palousc Region 



cm. long, greenish: flowers on pedicels 5-10 mm. long: valves 3-4 mm. long, 

 broadly ovate or cordate, each bearing a tubercle: akene about 2-2.5 mm. 

 long, brown. A weed in grain fields and along roadsides. 



R. salicifolius Weinm. Stems erect or decumbent, 40-90 cm. long, slightly 

 grooved, often branched below: leaves oblong-lanceolate, mostly acute, en- 

 tire, rounded or cuneate at the base, S-15 cm. long; petioles rather short: 

 panicle 10-12 cm. long, the branches short, leafy-bracted: valves triangular- 

 ovate, slightly toothed, 3-4 mm. long, each bearing a large oblong tubercle: 

 akene broad, 2 mm. long. Wet places, common. 



94. POLYGONUM. 



Annual or perennial, terrestrial or aquatic herbs, some species 

 woody: stems erect, prostrate, climbing or floating: leaves alter- 

 nate, sessile or petioled, continuous with or jointed to the cylindric 

 funnelform or 2-lobed often lacerate or fringed ocreae: flowers 

 small, perfect, green, white, pink or purple, variously clustered, 

 the clusters terminal or axillary; pedicels jointed, subtended by 

 ocreae: calyx 4-5-parted or cleft, the outer segments larger than 

 the inner: stamens 3-9: stigmas capitate: akene lenticular or 

 3-angled (rarely 4-angled), invested by or exceeding the calyx. 



Annual: stems twining: leaves cordate. P. convolvulus. 



Annual: stems wiry: leaves small, narrow. 



Prostrate: branches leafy to the tips. P. aviculare. 



Erect: flowers loosely scattered. 



Flowers pink with green midribs, campanulate, 2-3 mm. long: 



branches few, erect. P. DOUGLASii. 



Flowers white, broadly funnelform, 3.5-4.5 mm. long: branches 

 many, spreading. P. MAJUS. 



Erect: flowers dense. 



Bracts lanceolate, green, entire. 

 Bracts oblong, white-margined, crenulate. 

 Annuals: leaves rather large: stem not wiry. 

 Flowers pink: sheaths bristly-ciliate. 

 Flowers white: bracts naked. 

 Perennials: leaves large: stems not wiry. 

 Erect: racemes solitary: flowers white. 

 Decumbent or floating: flowers pink. 



Leaves oblong-lanceolate, acuminate. 

 Leaves elliptic, not acuminate. 



P. Convolvulus L. Annual: stems twining or prostrate, .5-1 m. long, 

 glabrous or pubescent, scurfy below: leaves heart-shaped or somewhat 

 halberd-shaped, acuminate, 2-6 cm. long, minutely scurfy beneath; petioles 

 equalling or shorter than the blades; ocreae short: flowers in clusters or 

 slender axillary leafy racemes: calyx 5-parted, closely investing the fruit: 

 akene 3-angled, dull black, minutely roughened. Introduced in cultivated 

 or waste soil. 



P. aviculare L. Annual, glabrous: stems slender, prostrate, much 

 branched, forming dense mats, the branches leafy to the top: leaves oblong 

 or lanceolate, acute, 1-3 cm. long, nearly sessile; ocreae scarious, cut into 

 lobes: flowers 1 or few in the upper axils, pink, on very short pedicels which 



