10. 
a A i 
E2; 
13. 
14. 
15. 
16. 
ed 
PAPERS ON BOTANY 187 
Triangular in cross section. 7. 
Not triangular in cross section. 10. 
Achene black, granular, angles rounded. Polygonum Con- 
volvulus. 
Achene brown. 8. 
Achene attenuate at apex. 9. 
Achene not attenuate at apex, 1 to 1.5 mm. long. Rumex 
Acetosella. 
Achene shiny, 1.5 to 2.5 mm. long. Rumex crispus. 
Achene not shiny, 2 mm. long, acuminate. Rumex obtusi- 
folius. 
Canoe shaped. 11. 
Not canoe shaped. 12. 
Convex side with groove across the middle. Plantago 
aristata. 
Convex side not grooved. Plantago lanceolata. 
Surface sculptured. 18. 
Surface not sculptured. 17. 
Surface granular. 14. 
Surface otherwise. 16. 
Achene jet black, flattened. Polygonum pennsylvanicum. 
Seeds not jet black. 15. 
Reddish to yellow, flat, two-thirds ovate. Lepidium vir- 
ginicum. 
Brown to black, coarsely granular. Plantago Rugelii. 
- Lemon yellow, slightly double convex. Solanum carolin- 
ense. 
Achene having vertical stripes. Cirsium lanceolatum. 
Surface having vertical lines. Digitaria sanguinalis. 
Achene having vertical spotted ridges. Lactuca scariola. 
Achene having warty ribs, obovoid. Anthemis Cotula. 
Seed coiled, conical. Salsoli Kali. 
Seed with 3 to 6 curved rows of tubercles. 
Seed brownish, flattened. Stellaria media. 
Seed lead colored, .5 mm. in diameter. Silene antir- 
rhina. 
Seed wrinkled, base white-tubercled. Lithospermum ar- 
vense. 
