136 ILLINOIS ACADEMY OF SCIENCE 
letins and other literature which list troublesome weed-seeds 
in grains, and by the writer’s experience with weed-seeds on the 
farm, the thirty-one seeds and fruits, which make up the key, 
were selected. 
The descriptions have been made with the use of a lens which 
magnifies about ten diameters. A simple lens known as “linen 
tester” gives very good results. Photographs show seeds and 
fruits magnified four diameters. Descriptions were made and 
photographs taken of the fruits after they were rubbed between 
thumb and forefinger. The nomenclature and order of classi- 
fication are those of Gray’s New Manual of Botany, seventh 
edition, 1908. When other names are used in common manu- 
als they are placed in parenthesis. 
Two previous weed-seed keys have been made. One by Edgar 
Brown and F. H. Hillman, keying the seeds of six species of 
Poa as found in commercial seeds. “The Seeds of the Blue 
Grass” Bulletin 84 of Bureau of Plant Industry, U. S. D. A. 
The other by E. L. Palmer in which he makes a seed key to 
some common weeds and plants. “A Seed Key to some Common 
Weeds and Plants,” Iowa State Academy of Science, 1916. The 
work was done under the direction of Professor William Tre- 
lease of the Botany Department of the University of Illinois. 
The writer desires to acknowledge the many helpful sugges- 
tions received. 
Tue Key 
1. Terminal appendages present. 2. 
Terminal appendages absent. 4. 
2. Appendages stiff, spiny; fruit top-shaped. Ambrosia arte- 
misiifolia. . 
Appendages scale- or bristle-like. 3. 
3. Achene with 2 rows of scales at apex. Cichorium Intybus. 
Achene with a whorl of short bristles at apex. Erigeron 
annuus. 
4. Seeds shot-like. 5.- 
Seeds or schemes not shot-like. 6. 
5. Seeds black, surface scarcely raticulated. Brassica 
arvensis. 
Seeds brownish, surface distinctly reticulated. Brassica 
nigra. 
