114 FARM WEEDS OF CANADA 



WHITE EVENING PRIMROSE (Oenothera pallida Lindl.) 



Other English name: White-stemmed Evening Primrose. 



Other Latin names: Oenothera albicaulis Niitt. and Canadian 

 authors; Anogr a pallida {Lindl. ) Britton. 



Native. Perennial. Roots white and fleshy, wide-spread- 

 ing and throwing up flowering stems at intervals, thus forming 

 large patches. Stems mostly simple, shining white, sparsely 

 downy above, erect or nearly so, about 3 feet high. Leaves from 

 1 to 4 inches long, narrow and waved, sometimes pinnatifid 

 but usually without teeth or divisions in plants found in the 

 West. Flowers axillary, large and handsome, 1| inches across, 

 waxy-white, turning pinkish as they fade, open in day time, 

 odour unpleasant. Tips of the calyx divisions at the ends 

 of the buds free, as 4 little points. Capsules narrow and curved, 

 4-angled, about 1 inch long with the seeds in single rows in each 

 of the 4 cells. 



The seed (Plate 74, fig. 52) is about 1/16 of an inch long, 

 normally spindle-shaped but angular and somewhat twisted 

 by compression in the pod, smooth and mucilaginous when 

 soaked, yellowish-brown; under the microscope minutely dotted 

 with black and faintly striate lengthwise. 



Time of flowering: July- August; seeds ripe in September. 



Propagation: By seeds and extensive deep-running fleshy 

 rootstocks, every part of which when broken will throw out 

 shoots and form new plants. 



Occurrence : Manitoba and westward to British Columbia. 



Injury: This deep-rooted perennial is very persistent in 

 sandy land. 



Remedy: Summer-fallow with deep or shallow plowing, 

 according to the nature of the soil, after the growth has been 

 made in summer. Cultivate in fall or in spring before seeding 

 to a crop. 



