A SEED KEY TO COMMON WEEDS 389 



4. Dark gray or black when mature. 



5. Dull lead-colored, almost circular, not over .5 mm. 



in diameter Arenaria serpyllifolia L. 28 



5. Almost shiny black, more ovate in shape, over 



.5 mm. in diameter Portulaca oleracea L. 35 



4. Distinctly reddish to red-brown in color. 

 5. Over .8 mm. in diameter with 5-6 curved rows of 

 minute tubercle-like projections on each face, 



dark (fig. XXXIV) Stellaria media L. Cyril. 29 



5. Under .8 mm. in diameter with coarser tubercles, 



lighter Cerastium viscosum L. 30 



2. Surface smooth, not pitted or tubercled. 

 3. Flat, nearly circular without a noticeable notch but 

 with a short projection on the margin and a narrow 



wing Ranunculus abortivus L. 36 



3. Not flat, narrow winged or circular. 

 4. Dark brown to black, with an oily appearance, 



under .8 mm. in length, broadly oval 



Eragrostis megastachya Host. S 



4. Not dark brown to black, usually over .8 mm. long. 

 5. Nearly spherical, minutely pitted or with a dis- 

 tinct granular appearance. 

 6. Pits quite distinct under a microscope, with a 

 pronounced concavity at the scar, usually 

 under .9 mm. long. .Cuscuta epithymum Murr. 64 

 6. Pits not markedly distinct, more granular in 

 appearance, not markedly concave at scar but 

 with more marked flattened areas than the 

 next preceding species. 



Cuscuta arvensis Beyrich 65 



5. Not spherical, pitted or with granular appearance. 



6. Somewhat shield-shaped with a notch at apical 



end, a slight groove on each side of the notch. 



7. Green to black Trifolium hybridum L. 48 



7. Yellowish to light brown. .Trifolium repens L. 47 

 6. Not shield-shaped or with grooves. 



7. Surface finely hairy, flattened oval, tapering 



at the base Erigeron cayiadensis L. 84 



7. Somewhat spindle-shaped with a scar at the 

 broader end extending not over one-fourth 

 length of the seed Agrostis alba Schrad. 7 



