78 FARM WEEDS OF CANADA 



to identify them. The leaves and stems of many bear small, 

 star-shaped hairs. The flowers are regular, composed of four 

 free calyx divisions and four free corolla divisions, arranged 

 in two opposite pairs and forming a cross-shaped flower, from 

 which the whole family takes its name, Crudferae. The flowers 

 are borne on footstalks and clustered at the tips of branches 

 which gradually elongate, forming long, upright racemes, often 

 with fully formed and even ripe pods below, before the topmost 

 flowers have opened. When ripe the seed pods, which are of 

 various shapes, usually consist of two outside walls separated by 

 a thin white partition, to the sides of which the seeds are attached. 



The seeds as a rule are small and numerous. Their surface 

 is usually rather dull and more or less granular. Many, when 

 placed in water, develop a coat of mucilage, by which, when dry, 

 they remain attached to passing objects or adjacent surfaces. 

 This is an important factor in their distribution. The quantity 

 of mucilage developed varies ; on some seeds it remains after 

 drying as a covering of hair-like points or threads. The seed- 

 coat is generally thin and close-fitting, the position of the germ 

 showing plainly through it. 



WOOD WHITLOW GRASS (Draba nemorosa L.). 

 Other English name : Yellow Whitlow Grass. 



Native. Annual and winter annual. Slightly downy. Stem 

 low, branching below, leafy to the elongated raceme. Leaves 

 stalkless, oblong-ovate or lance-shaped, somewhat toothed. 

 Flowers whitish yellow. Pods elliptical-oblong, half the length 

 of the footstalks, which are almost horizontal at maturity. 



The seed (Plate 73, fig. 28) is small, 1/16 of an inch long, 

 egg-shaped, flattened, reddish brown, with a rough surface. 



Time of flowering : Early June; seeds ripe by end of June. 

 Propagation : By seeds. 



