A SEED KEY TO COMMON WEEDS 373 



6. Not nearly square in cross section with 10 longi- 

 tudinal ridges Hieracium sp. 117-118 



Not black or nearly so. 

 3. With numerous short terminal appendages and one long 



beak, turbinate Ambrosia artemisiifolia L. 86 



3. With a double row of short persistent scales at termi- 

 nal end (tig. II) Cichorium Intybus L. 107 



3. Without numerous terminal appendages. 

 4. Surface markedly shining. 

 5. Very dark brown, oval, a small whitish appendage 

 near hihim, tapering at both ends (fig. XXV) 



Prunella vulgaris L. 71 



5. Light brown or tan, not tapering at both ends, a 



cuplike collar at apex (fig. VIII) 



Cirsium arvense L. Scop. 105 



4. Surface not markedly shining. 

 5. Surface covered with about 10 longitudinal rows of 



tubercle-like projections (fig. XXVII) 



Anthemis Cotula L. 97 



5. Longitudinal lines if present not composed of tu- 

 bercle-like projections. 

 6. Thin and wafer-like, flattened. 



7. With a narrow wing, 3 to 5 regular ridges and 



broadest near middle 



Sonchus asper L. Hill. 112 



7. Without a wing, broadest toward apex 



Sonchus oleraceus L. Ill 



6. Not thin and wafer-like. 

 7. Plano-convex or concavo-convex. 

 8. Broad, with longitudinal rows on the surface 

 usually composed of short bristles, not red- 

 dish Baucus Carota L. 69 



8. Narrow, without many longitudinal rows of 



bristles Digitaria sanguinalis (L.) Scop. 1 



7. Not plano-convex or concavo-convex. 

 8. Comparatively short and distinctly triangu- 

 lar in cross section. 



9. Equally 3-sided, angles not rounded 



Rumex obtusifolius L. 14 



9. Unequally 3-sided, angles slightly rounded 



Polygonum avicu:are L. 16 



8. Not distinctly triangular in cross section. 

 9. Light straw-colored, broad at apex, con- 

 tracted at base, with about 9 longitudi- 

 nal grooves (fig. XXVI) 



Anthem is arvensis L. 97 



9. Not light straw-colored or noticeably broad- 

 er at the apex. 



