128 SELECTED WESTERN FLORA . 



6. P. Purshii, R. and S. 



White silky-woolly; leaves oblong to linear; spike slender, dense. Ljry 

 prairies, N. Saak. and Alta. 



LXXXI. RUBIACEjE (Madder Family). 



Herbs. — in our climate, — with entire leaves, either opposite and 

 connected by stipules or in whorls without stipules, and regular 

 perfect flowers. Calyx gamosepalous, variously toothed; coroUa 

 4 or 5-lobed; stamens as many as the lobes of the corolla and alternate 

 with them, inserted on the throat; style either short or long; ovary 

 1-10-celled, many-ovuled; fruit a capsule, berry, or drupe. A very 

 large family but mostly tropical. 



1. GALIUM. Bbdstraw. 



Calyx teeth obsolete; corolla rotatOj 4-lobed; stamens 4, or 

 rarely 3, with short filaments; styles 2; fruit double, of two either 

 dry or fleshy parts separating into indehiscent 1-seeded carpels. 

 Slender,, often trailing herbs with small flowers, square stems, and 

 whorled leaves. 



1. G. boreSle, L. Nobthern Bedsteaw. • 



Smooth, erect, 6-18 in. high; leaves in 4's, linear to lanceolate; flowers 

 white, in close panicles; fruit often bristly. Dry prairies, common, Man.- 

 Alta. 



2. G. trifldrum, Miohx. 



Stem diffuse, ascending or procumbent, glabrous but a little roughened 

 on the angles ; leaves elliptical to lanceolate, slightly roughened on the mar- 

 gins and often bristle-pointed ; peduncles 3-flowered ; flowers greenish-white ; 

 fruit covered with hooked bristles. Moist shady places, Man.-Alta. 



3. G. trifidum, L. 



Stem very weak, slender, diffusely branched, forming a mat on the ground ; 

 leaves linear to spatulate, usually in 4's; flowers whitish, solitary except the 

 terminal, which may be in 3's. Wet shady places, Man.-Alta. 



2. HOUSTONIA. 



Calyx 4-lobed, persistent ; corolla 4-lobed, usually longer than the 

 calyx; stamens 4, inserted on the throat of the corolla; style 'l; 

 stigmas 2; ovary 2-celled. Erect, low, tufted herbs with opposite 

 entire leaves and small bluish, purplish, or white flowers. 



