THE SUNFLOWER FAMILY 165 



headed Sunflower (Helianthus scaberrimus Ell.) and Many- 

 flowered Prairie Sunflower {Helianthus Maximiliani Schrad.) 

 are the most abundant, but Wild Artichoke (Helianthus 

 doronicoides Lam.) is the most difficult to eradicate; for all 

 these, early summer-fallowing is the best method. 



The seeds are often found among western grain. The 

 seed of Many-flowered Prairie Sunflower (Plate 75, fig. 81) is about 

 1/6 of an inch long, brown, variable in shape but mostly narrowly 

 oblong, egg-shaped in outline, flattened and rather angular, 

 grooved lertgthwise, cross-mottled with irregular, zigzag, white 

 lines; both scars, at the top and the base, are conspicuous, 

 the latter rather oblique. 



The Bur Marigolds or Beggar-ticks (genus Bidens) are mostly 

 swamp and wet meadow plants. One of them. Common 

 Beggar-tick or Pitch-forks (Bidens frondosa L.) is a native weed 

 of general distribution. It is a tall, branching annual, with 

 3 to 5 divided leaves and yellow flowers. The seed is enclosed 

 in a flat, wedge-shaped fruit, often roughened with tubercles, 

 olive brown, about 1/4 to 1/3 of an inch long, provided with 

 2 awns, 1/2 as long as the fruit itself, downwardly barbed. 



Close cutting from year to year when the plant is in early 

 bloom will keep this weed in check by preventing the production 

 of seed. 



TRIBE HELENIEAE 



The only member of this tribe that is recognized as a weed 

 is Sneezeweed, False Sunflower or Yellow Star (Helenimn 

 autumnale L.), a native perennial found in moist soils, much 

 resembling some species of sunflowers. The whole plant is 

 aromatic, resinous. The leaves are firm, oblong-lance-shaped, 

 generally toothed, wing-like, and extend down the stem. The 

 bright yellow rays are 3-cleft. 



The seed is about 1/12 of an inch long, angled, ribbed, 

 hairy on the angles. The pappus consists of chaffy scales running 

 into bristles. 



