8 ILLUSTRATIONS 



Page 

 Fig. 24. Corn cockle: three stages of seedling growth; also en- 

 larged drawing of seed 46 



25. Corn cockle: mature plant 47 



26. White cockle: three stages of seedling growth; also en- 



larged drawing of seed 48 



27. White cockle: flower, root system, separate flower, and 



mature pod 49 



28. French weed: three stages of seedling growth; also en- 



larged drawing of seed 52 



29. French weed: mature plant 53 



30. Peppergrass: three stages of seedling growth; also en- 



larged drawing of seed 54 



31. Peppergrass: mature plant, branch with fruit, and 



enlarged pod 55 



32. Shepherd's purse: three stages of seedling growth; also 



enlarged drawing of seed 56 



33. Shepherd's purse: mature plant 57 



34. Wild mustard: three stages of seedling growth; also 



enlarged drawing of seed 60 



35. Wild mustard: mature plant 61 



36. Yellow trefoil: three stages of seedling growth; also 



enlarged drawing of seed and fruit 62 



37. Yellow trefoil: showing both flowers and fruit 63 



38. Sweet clover: three stages of seedling growth; also en- 



larged drawing of seed and fruit 66 



39. Sweet clover: mature branch and enlarged flower 67 



40. Kinghcad: three stages of seedling growth; also enlarged 



drawing of seed 68 



41. Kinghead: mature plant 69 



42. Ragweed: three stages of seedling growth; also enlarged 



drawing of seed 70 



43. Ragweed : mature plant 71 



44. Burdock: three slaves of seedling growth; also enlarged 



drawing of seed 74 



45. Burdock: showing top of plant with burs; also Large 



basal leaf 75 



46. Canada thistle: three stages of seedling growth; also 



enlarged drawing of seed 76 



47. Canada thistle: mature plant 77 



48. Bull thistle: three stages of seedling growth; also en- 



larged drawing of seed 78 



4<). Bull thistle: mature plant 79 



