LIST OF ILLUSTRATIONS 



FIGURE PAGE 



Fireweed Frontispiece 



1. Canada Thistle Seed 7 



2. Woolly Thistle Plant 8 



3. Pigeon Grass 9 



4. Root of Milkweed 11 



5. Scattering of Red Cedar by Birds 14 



6. Tumble Weed 15 



7. Bull Thistle "Seed" 16 



8. Seed of Vegetable Oyster 17 



9. Ragweed Sunflower, and Foxtail Seeds 17 



10. Seed of Sedge 18 



11. Arrow-Head Seed 18 



12. Cast from Crow Containing Various Seeds 19 



13. Goldfinch Eating Dandelion Seeds 20 



14. Pod of Licorice; "Seed" of Cocklebur; Section of Carrot Seed 20 



15. Burdock Head 21 



16. "Seeds" of Pitchforks 21 



17. Seeds Scattered through Explosive Properties 21 



18. Explosive Seeds and Fruits 22 



19. Seeds Distributed with Wheat Seed 23 



20. Russian Thistle Seed 24 



21. Ragweed Seed 24 



22. Foxtail Seed 24 



23. Plaintain Seed 25 



24. Smartweed Seeds 25 



25. Wild Carrot Seeds 25 



26. Canada Thistle Seeds 26 



27. Impurities in Red Clover Seeds 34 



28. Red Clover and Sweet Clover Seeds 35 



29. Impurities in Alsike Clover Seeds 35 



30. Impurities in Alfalfa Seeds 36 



31. Seeds of Kentucky and Canadian Blue Grass 36 



32. Seeds of Various Grasses 37 



33. White Weed 53 



33a. California Poison Ivy 63 



33b. Poison Ivy 64 



33c., 33d., 34., Maps Showing Distribution of Various Weeds 77, 79, 82 



34a. Wild Morning Glory 113 



35. Fibrous Root of Crab Grass 114 



36. Root Cap 114 



37. Root Hair 115 



38. Wild Buckwheat 116 



39. Brace Roots of Corn 117 



40. Cross-Section of an Endogenous Stem of Corn 118 



41. Tendrils of Japanese Ivy 118 



42. Tendril of Star Cucumber 119 



43. Horse Chestnut Leaf 119 



44. Rose Leaf 120 



45. Parts of a Leaf 120 



46. Parallel-Veined Leaves 121 



47. Sassafras Leaf 121 



48. Aconite Leaf 122 



49. Leaves of Various Types 122 



50. Radiate-Veined Leaves 122 



51-57. Various Types of Leaves 123 



58. Catkin of Birch <. 124 



59. Cymose Cluster of Pink- 124 



60. Spike of Cat-Tail 125 



61. Head and Achene of Ragweed 125 



ix 



