1 IOWA ACADEMY OF SCIENCES. 



2. Black aud shiuy, 1" or more broad; abruptly tipped with a short 

 . point. 

 a Gibbons flattened, sometimes slightly triangular; orbicular to 

 slightly ovate; l-lj" broad. 



Polygo7mm persicaria, L. 

 b Concave on both sides; oi'bicular; li-lf" broad. 

 Polygonum pennsylvanicum, L. 



IV. Seeds sharply angled in various ways, but not triangular; not 



achenes. 

 1. Dull black or brown seeds with one convex face which is more or 

 less rough. Angles not winged except in Verbena hastata. 

 a Nearly uniform in size throughout the entire length of the seed; 

 length, 2i-3 times the thickness; 3-faced, one convex, the 

 other two plane and meeting in a moderately sharp angle; light 

 brown. 



Verbena. 

 * Convex face prominently 4-ridged longitudinally; upper half 

 transversely wrinkled. 



/ Length, 1-1 i"; plane faces with whitish roughen- 

 ing. 



V. bracleosa, Michx. 

 // Length, 1-1 V'; little or no whitish roughening on 

 plane faces. 



V. angusiifolia, Michx. 

 Jff Length, l^-H"; otherwise same as in V. angusii- 

 folia. 



V. stricta, Vent. 

 ** Not prominently ridged nor wrinkled. 



f Length, |-1"; angles not winged. 



V. urtica;folia, L. 

 ff Length, 1"; angles between the convex face aud the 

 plane faces slightly winged. 

 V. hastata, L. 

 b Seeds flattish; angled in various ways; smaller at the ends than 

 in the middle. 



/ Dark brown, nearly black; length, f-lj". 



Plantago rugelii, Decaisne. 

 jy Light brown; length, i". 

 Planlago major, L. 

 3. Seeds irregular and winged on the angles, giving them a shriveled 

 appeM-ance; light brown; length, |". 

 (Enothera biennis, L. 



V. Obconical achenes; longitudinally ribbed; light colored. 



1. Ribs beset with tubercles; light brown; length, |". 



Anthemis cotula, D. C. 



2. Not tubercled; truncate at apex; length, f"; lighter colored than 



last. 



Anthemis arvensis, L. 



3. More slender; stripes of black between the ribs; f" long. 



Chrysanthemum leucanthenitim, L. 



