442 



WEED FLORA OF IOWA 



W 



\ 



cn> 







9 



Figure 288A Figure 288B 



Fig. 288. A. Small Peppergrass (Lepidium apetalum). A, seeds shown in side 

 view ; B, a half-section of a pod ; C, a seed in cross section, showing the 

 three parts of the embryo, the caulicle being at the right ; D, the embryo, 

 the caulicle at the left ; E, group of seeds, natural size. 



B. Lepidium apetalum, with section of seed coat showing action of mucilagin- 

 ous cells after moistening. 

 (A, after Hillman, Bull. Nev. Agr. Exp. Sta. ; B, drawn by C. M. King.) 



Large Peppergrass {Lepidium virginicum L.). 



Seed elongated with prominent ridge on one side, one-twelfth in. 

 in length; color light reddish brown; cotyledons incumbent; seed 



Fig. 289. Large Peppergrass (Lepidium virginicum). A, three seeds shown 

 in side view. The upper two show the narrow, curved groove of one face, 

 the lower one shows the broader, shallow depression of the opposite face. 

 The one immediately at the right of A shows the widened border and its 

 light colored edge. B, entire pod. C, a seed showing the mucilage as it 

 appears while wet. D is a cross sectional view of a seed, showing the 

 flattened form of the cotyledons and the edgewise position of the caulicle. 

 E, the embryo in side view. F, seeds, pod, and half-pod, natural size. 

 (After Hillman, Bull. Nev. Agr. Exp. Sta.) 



coat becomes mucilaginous when wet. Generally found in small 

 grains and commercial grass seed. Frequent in timothy. 



