36 



SELECTED WESTERN FLORA 



2. POLYGONUM. Knotgrass. 



Calyx mostly 5-parted, the divisions often petal-like, and usually 

 withering; styles or stigmas 2 or 3; aohene angled according to the 

 number of stigmas. Slender or prostrate herbs usually 

 from fibrous roots. 



1. P. aviculare, L. Knotgrass. 



Leaves small, lanceolate, with the flowers in the axils; sepals 



small, green with pink borders; stamens 5 or 8. Slender or 

 prostrate herbs of a bluish green color forming a mat 

 on the ground. Very common around dwellings ; intro- 

 duced. 



2. P. amphibium, L. 



Stem slender, ascending or prostrate; leaves ellip- 

 tical to lanceolate ; pike dense ; flowers bright rose-pink. 

 ' Aquatic herbs but 



continuing to grow in 

 the mud after the 

 water has dried up; 

 the leaves long-peti- 

 oled, floating, and the 

 spikes of rose-colored 

 flowers protruding 

 from the surface of 

 the water or standing erect above the decumbent or prostrate stems. 

 Man.-Alta. • 



Fig. 33. — Polygonum aviculare. 



3. P. Convolvulus, L. Wild Buckwheat or Black Bindweed. 



A twining or ijrooumbent annual with slightly halberd-shaped leaves and 

 irregular racemes of small whitisli flowers; achene 3-angled, black. A 

 common introduced weed. 



4. P. viviparum, L. 



Stem low, simple, glabrous, erect, from a corm-like rootstock; root leaves 

 oblong, petioled, cordate; stem leaves linear or lanceolate, sessile; raceme 

 terminal, strict, rather dense, with some dark-colored bulblets j.ust below 

 the base. Swampy places, W. Alta. 



3. eri6gonum. 



Calyx 6-parted, colored, persistent; stamens 9, on the calyx ; 

 styles 3; achene triangular. Mostly perennial herbs with the 

 flowers on short pedicels mixed with narrow chaffy bracts, and sur- 

 rounded by a 4-8-lobed involucre. 



