A SEED KEY TO COMMON WEEDS 343 



31. Agrostemma Githago L. Corn Cockle. L. 2.8 — 3.5 mm. 

 W. 2.5 — 3.3 mm. C, dark brown to black. S., irregularly 

 round with two broad shallow grooves following the outline of 

 the cotyledons, quite angular; surface covered with numerous 

 (about thirty) rows of short rounded elevations. 0., "common 

 in seeds of cereals, millets, vetches and flax from all sources" 

 (Hillman). Introduced from Europe. 



32. Lychnis alba. Mill. White Campion. L. 1.2—1.8 mm. 

 W. 1.2 — 1.4 mm. C, dusty yellow with numerous black topped 

 tubercles. S., short kidney-shaped with about fifteen rows of 

 tubercles on each side, base of tubercles not notched as in Silene 

 noctiflora L. 0., rather common along roadsides. Introduced 

 from the Old World. 



33. Silene noctiflora L. Night-flowering Catch-fly. L. 1.2 

 — 1.8 mm. W. 1. — 1.3 mm. C, gray-brown with a slight red- 

 dish or pink tinge. S., very short kidney-shaped; flattened 

 especially on one side ; surface covered with concentric rows of 

 glandular-like structures. 0., common and often abundant in 

 seeds of red and alsike clovers. Introduced from Europe. 



34. Saponaria officinalis L. Soapwort or Bouncing-Bet. L. 

 1.8—2.4 mm. W. 1.8—2.4 mm. C, dark bluish black. S., 

 short kidney-shaped to circular with a notch on one side; sur- 

 face covered with concentric rows of tubercle-like projections. 

 0., sandy land and roadsides; in various farm seeds. Natural- 

 ized from Europe. 



35. PorUtlaca oleracea L. Purslane, Pussley. L. .5 — .8 mm. 

 W. .3 — .6 mm. C, shining black or sometimes with a purplish 

 tinge. S., broadly ovate, flattened ; sometimes almost circular 

 but usally quite pointed near the scar; surface covered with 

 numerous shallow cavities; one large cavity running from the 

 scar back along the seed. 0., very common in gardens and in 

 waste lands. Introduced from the southwest. 



36. Ranunculus abortivus. L. Small flowered Crowfoot. L. 

 .8 — 1.4 mm. W. .6 — 1.2 mm. C, light yellowish brown. S., 

 lenticular in cross section, slightly winged around the margin: 

 a beak at the end short and curved ; surface wrinkled radially 

 around the margin. 0., not particularly common but very 

 abundant in certain regions. Introduced from Europe. 



37. Ranunculus acris L. Tall Crowfoot or Tall or Bitter 

 Buttercup. L. 2.5 — 4. mm. W. 2.5 — 3.5 mm. C, dark brown 



