450 



WEED FLORA OF IOWA 



Prairie Rose (Rosa pratincola Greene). 



Achenes dark to light brown, smooth, shining; length 3-5 mm., 

 width 2-3 mm., general shape ovoid, modified by some flattening of 

 portions at the surface, and corresponding angulation of the seed's 

 form; scar at broader end, with dark line extending to the apex 

 which is tipped with a slight remnant of the style. 



LEGUMINOSAE, PULSE FAMILY. 



Rattlebox (Crotalaria sagittalis L.). 



Pod blackish, cylindrical, inflated, many seeded; seed greenish 

 brown, shining, smooth, somewhat flattened, circular-kidney-shaped, 



Fig. 304. Rattlebox (Crotalaria sagittalis). 

 (Drawing by Ada Hayden.) 



with one side interrupted by a deep rounded notch, bearing the 

 conspicuous scar with dark center and light rim; width of seed 

 2.5 mm. 



White Clover (Trifolium repens L.). 



Seeds varying from nearly square to triangular, margins rounded, 

 flattened, often concave on one margin, one-twentieth to one-thir- 

 tieth in. long ; smooth ; color dull yellow to light reddish brown, or 

 slightly green; radicle slender club-shaped, about as long as the 

 cotyledons. 



Alsike Clover (Trifolium hyoridum L.). 



Seed more nearly round than that of alfalfa or red clover; one- 

 twentieth to one-sixteenth in. in length ; color a peculiar yellowish 

 green, often brown and mottled, individual seeds even yellow or 

 brown ; the projecting radicle gives the seed the appearance of hav- 

 ing a nearly square top. 



