388 IOWA ACADEMY OF SCIENCE 



4. Long oval or irregular in shape with a groove 

 running the entire length of the seed and onto 



the end Sisymbrium officinale Scop. 41 



4. With a double or looped groove 



Capsella Bursa-pastoris A. Medic. 39 



3. Black or with slight brown cast at apex, pointed 



at both ends Glyceria nervata Trin. 10 



2. Without a groove running more than one-half length of 

 seed. 

 3. Thickest in the middle coming to a more or less acute 

 angle at the edge, notch at scar very shallow. 



4. Ovate, angle at edge more rounded 



Amaranthus retroflexus L. 24 



4. Round, angle at edge distinct, slightly smaller than 



next preceding Amaranthus graecizans L. 26 



3. Angles at edges rounded, notch at scar quite marked. 



4. Green to black Trifolium hybridum L. 48 



4. Yellow to light brown Trijolium repens L. 47 



II. Not shining. 



III. With distinct forked curved wrinkles or ridges, light 



colored Potentilla monspelicnsis L. 44 



III. Without distinct forked curved wrinkles or ridges. 



1. Surface with a longitudinal groove starting at one end, 

 not pitted. 

 2. Groove looped or double, not running the entire length 



of the seed (fig. XL) . .Capsella Bursa-pastoris A. Medic. 39 

 2. Groove not double but running entire length of seed .... 



Sisymbrium officinale Scop. 41 



1. Surface without a longitudinal groove starting at one end. 

 2. Surface finely pitted qr with numerous tubercle-like 

 elevations. 

 3. Surface pitted. 

 4. Nearly cylindrical, one end smaller than the other, 



pits deep (fig. XXIV) 



Verbascum Thapsus L. or Blattaria L. 74 



4. Not cylindrical. 



5. A slight groove at one end, grayish brown (fig. 



XXXIX) Barbarea vulgaris R. Br. 42 



5. Without a groove at one end. 



6. Pits quite distinct under a microscope; with 

 quite 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 in next 

 preceding species. .. .Cuscuta arvensis Beyrich 65 

 3. Surface with concentric or eccentric rows of tubercle- 

 like projections. 



