THE SUNFLOWER FAMILY 149 



ALLIED SPECIES: False Ragweed (Iva xanthifolia Nutt.), 

 a coarse annual which grows to a height of 6 to 8 feet and produces 

 an enormous quantity of seed. Before flowering it has a remark- 

 able superficial resemblance to Great^ Ragweed, having the 

 same habit of growth and leaf outline; but it can be recognized 

 at once by the stem, which is perfectly smooth, while in Great 

 Ragweed both the stems and the leaves are noticeably rough; 

 when full grown, the resemblance between the two plants dis- 

 appears. False Ragweed bears a large, loose panicle of dark- 

 coloured flowers at the top of the stem, while Great Ragweed 

 has a long, rat-tail-like spike of male flowers at the tip of each 

 branch. 



The seed (Plate 75, fig. 76) is of the same general shape 

 as that of Poverty Weed, but is only 1/10 of an inch long, more 

 tapering and finer, somewhat darker in colour, the surface 

 finely striated lengthwise. When fresh it has a gray, mealy 

 covering, which partially rubs off and gives it a mottled appear- 

 ance. It is ocassionally found among grain, grass and alfalfa 

 seed of western production. 



False Ragweed is quite common in parts of the West, 

 occuring principally in rich land around farm buildings and 

 waste places. It does not often give trouble in cultivated fields, 

 and can be kept in check by repeated cutting to prevent seeding. 



The seeds of some weeds, particularly the different species of the thistle, are car- 

 ried to a considerable distance by the wind; and where any earth is grown up in such 

 a manner as to intangle them, as at the root of a hedge, or side of a ditch, there they appear 

 in great plenty. It is surprising, that many farmers allow them to grow there undis- 

 turbed: the consequence of which is, that their seeds are carried in great plenty into the 

 adjacent fields, and thereby great damage is done; which might have been prevented 

 by cutting them down, at a small expense, before their seeds were ripened. 



Adam Dickson, A Treatise on Agriculture, 1785. 



