460 WEED FLORA OF IOWA 



Common Mallow (Malva rotundifolia L.). 



Commonly called cheeses. Carpels arranged about a center, flat, 

 beakless, in dehiscent ; each carpel a single seed, kidney- shaped, one- 

 sixteenth to one-twelfth in. in diameter, flattened, with a prominent 



'^JF ^s^ ss# 



Fig. 322. Common Mallow (Malva. rotundifolia). A, two seeds in side view. 

 B, a seed retained by a carpel of the seed-vessel. C, a seed in cross section 

 taken midway between the scar and the opposite edge. D, seeds, showing 

 the natural size. 



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



notch at base; seeds brownish or gray, minutely granular; scar 

 small, frequently containing spongy tissue; embryo curved; small 

 amount of endosperm. Reported in alfalfa and red clover seed. 



Bladder Ketmia (Hibiscus trionum L.). 



Capsule 5-valved, globose-ovoid, hairy ; seeds kidney-shaped, one- 

 fifteenth in. in length, blackened, roughened by short tubercular 

 processes, minutely granular; basal end of seed of much smaller 

 diameter; scar brownish; funicle extending to the notch. 



ONAGRACEAE, EVENING PRIMROSE FAMILY. 



Evening Primrose (Oenothera biennis L.). 



Seeds prismatic, 4 or 5-sided, sometimes curved, variable, one- 

 sixteenth in. in length, slightly wing-margined, rugose, brown, scar 

 indistinct at one end, embryo straight. 



UMBELLIFERAE, PARSLEY FAMILY. 



Water Hemlock (Cicuta maculata L.). 



Fruit ovate to oval, curved or nearly straight, one-eighth in. in 

 length, smooth, with longitudinal brown and straw-colored lines ; 

 apex widened with 2 styles; ribs corky; oil-tubes solitary, in the 

 intervals. 



