A SEED KEY TO COMMON WEEDS 381 



2. With more than 3 longitudinal ridges, greenish in color 



(fig. XXX) Daucus Carota L. Gl 



2. With 3 or less longitudinal ridges. 

 3. Equilateral or very nearly so. 



4. Without pointed ends, angles sometimes indistinct, 



never over 2 mm. long Rumex Acctosella L. 15 



4. With pointed ends, angles very distinct, apical end 

 sharp pointed, basal end blunt pointed, shining. 

 5. Rarely under 2 mm. long, less shining than the 



following species, apex more acuminate 



Rumex obtusifolius L. 14 



5. Usually about 2 mm. long, shiny, apex not attenu- 

 ate, angles dip slightly just back of apex (fig. 



XXXVI ) Rumex crispus L. 13 



3. Not equilateral. 



4. Light straw-colored. 



5. Over 1.5 mm. long Setaria viridis K. Braw. 4 



5. Less than 1.5 mm. long Agrostis alba L. 7 



4. Not light straw-colored. 



5. Seed coat loosely fitting, irregularly shaped, brick 



red (fig. XII) Oenothera biennis L. 59 



5. Seed coat tightly fitting. 



6. Surface granular, usually black 



Plantago Rugelii Dene. 78 



6. Surface finely striate. 



7. Usually over 1.8 mm. long with a remnant of 

 calyx at one end, other end quite acuminate, 



striations quite straight 



Polygonum aviculare L. 16 



7. Usually under 1.8 mm. long, irregularly shaped, 



striations wavy, variously colored 



Plantago major L. 77 



1. Not triangular in cross section. 

 2. Black or nearly so. 

 3. Round with a wing. 



4. Wing very broad, seed very thin 



Linaria vulgaris Hill. 76 



4. Wing narrow, seed thick Spergula arvensis L. 27 



3. Without a wing. 

 4. Shining markedly. 



5. Slightly pointed at opposite ends, fairly thick edges 



rounded Polygonum Persicaria L. 17 



5. Not pointed at opposite ends. 



6. Calyx persistent, when rubbed off seeds slightly 

 flattened on both faces. 

 7. One side flattened more than the other, margin 

 not always rounded, slight curved groove on 

 one side Chenopodium allnim L. 22 



