PLATE V. 



Each magnified about 5 diameters. 



No. 1 Triticum spelta L Spelt, spikelet and seed 



2 Iva xanthiifolia (Fresen) Nutt Marsh Elder, 2 seeds. 



3 Iva ciiiata Willd Marsh Elder, 4 seeds. 



4 Ambrosia artemisicefolia L Ragweed, 4 seeds. 



5 Ambrosia trifida L Great Ragweed, 2 seeds. 



6 Helianthus annuiis L Sunflower, 2 seeds. 



7 Cardials arvensis (L) Robs Canada Thistle, 4 seeds. 



8 Cardials lanceolatus L Common Thistle, 2 seeds. 



9 Rudbeckia hirta L Yellow Daisy, 2 seeds. 



10 Leontodon autumnale L Fall Dandelion, 2 seeds. 



11 Arctium Lappa L Burdock, 2 seeds. 



12 Grindelia squarrosa (Pursh) Dunal Gum-plant, 4 seeds. 



13 Centaur ea "jfacea L Brown Knapweed, 2 seeds. 



14 Centaur ea solstitialis L Star Thistle, 2 seeds — these come with snd 



15 Centaur ea Cyanus L Blue-bottle, 2 seeds. [without pappus. 



From original photographs by P. A. Hinman and J. M, \ an Hook. 



