346 IOWA ACADEMY OF SCIENCE 



50. Medicago sativa L. Alfalfa, Lucerne. L., 1.8 — 2.5 mm. 

 W., 1. — 1.4 mm. C, greenish yellow to brown. S., kidney- 

 shaped to diamond-shaped with edges less rounded than in 

 Melilotus alba; slightly thinner and larger than Medicago lupu- 

 lina and without the prominent elevation near the scar. 0., 

 widely cultivated. Introduced from Europe. 



51. Medicago lupulina L. Yellow Trefoil, None-such, Black 

 Medick. L., 1.5 — 2.4 mm. W., .7 — 1. mm. C, yellowish green 

 or brown. S., flattened oval especially near the scar; with an 

 elevation near the scar extending beyond the general outline 

 of the seed. 0., found especially as an adulterant in alfalfa. 

 Introduced from Europe. 



52. Amphicarpa monoica (L.) Ell. Hog Peanut. L., 4.2 — 

 5.8 mm. W., 3.2 — 4.8 mm. C, purplish black mottled with 

 gray. S., short flattened oval with the hilum on the edge; 

 surface smooth. 0., not a bad weed; common in thickets grow- 

 ing over other weeds. Native. 



53. Rhus Toxicodendron L. Poison Ivy. L., 3. — 5.8 mm. 

 W., 2.8 — 5. mm. C, white or nearly so. S., fruit nearly globu- 

 lar, seed somewhat kidney-shaped with two flutings on each 

 side. 0., common in rocky and swamp places, shrubby or 

 climbing; poisonous. Native. 



54. Impatiens biflora Walt. Spotted Touch-me-not. L., 3.8 

 — 5.8 mm. W., 2. — 3.5 mm. C , usually quite dark reddish 

 brown. S., oval with a slight beak on one end and four or 

 sometimes five narrow longitudinal ridges on the sides; some- 

 what flattened with two ridges on the outer face and one down 

 each face; surface somewhat wrinkled. 0., common in damp 

 places and spreading quite rapidly. Native. 



55. Abutilon Theoplirasti. Medic. Indian Mallow, Velvet 

 Leaf. L., 3.2 — 4.4. mm. W., 2.6 — 3.4 mm. C, graying brown. 

 S., somewhat kidney-shaped to ovoid; resembling Datura but 

 having a much more pronounced notch; flattened. 0., flat 

 waste lands and in pastures. Introduced from India. 



56. Malva rotmidifolia L. Common Mallow, Cheeses. L., 

 1.2 — 2.2 mm. W., 1.2 — 1.8 mm. C, light greenish brown. S., 

 nearly circular except for a notch on one side; flattened and 

 slightly thinner on the side next the notch; seeds borne in 

 disc -like fruits. Introduced from Europe. 



