WEEDS OF THE THISTLE FAMILY. 



161 



another page. All have the top of the achenes or seeds armed with 



strongly barbed bristles or awns 

 by M'hieh they readily adhere to 

 clothing, wool or hair of animals 

 and thus are widely scattered. 

 The awns are usually 2 in num- 

 ber, whence the generic name Bi- 

 dens, meaning two-toothed. A 

 closely allied species is the com- 

 mon beggar-ticks {B. frondosa 

 L., Fig. 119), which is also very 

 common in moist soil in fence 

 corners, gardens, corn fields and 

 waste places. It has the leaves 

 3-5 divided, the outer bracts 

 larger and achenes wider with 

 more slender awns. The juices 

 sometimes cause an itching or 

 skin irritation when the plant is 

 handled. Both can be easily de- 

 stroyed by mowing before the seeds ripen, thorough cultivation or 

 improved drainage. 



Fig. 119. (After Vasey) 



120. Bidens bipinnata I* Spanish Needles. 



Stem erect, 4-sided, branched, 1-5 feet 

 high ; leaves stalked, 1-3 times divided into 

 oblong toothed or lobed segments. Heads 

 numerous, long-stalked ; involucre narrow, 

 its bracts linear, the inner ones the larger ; 

 flowers few, dull yellow ; rays none or 3-4, 

 short, yellow. Achenes linear, 4-sided, f 

 inch long, narrowed upward into a beak 

 which bears 3 or 4 short downwardly barbed 

 awns. (Fig. 120.) 



Common in gardens, cultivated fields, 

 borders of thickets and waste places, es- 

 pecially in rich moist soil. July-Oct. 

 Remedies: pulling or mowing before 

 the seeds ripen; burning over stubble 

 fields and waste places in autumn. 



127. 



(A. N. 2.) 



Fig. 120. Long inner fruit with barbed 

 awns; shorter and thicker outer fruit. 

 (After Britton and Brown.) 



Bcebera papposa Vent. Foetid Marigold. Yellow Dog-fennel. (A. 

 K. 2.) 

 Erect, glandular, strong-scented, very leafy, much branched, G-1S 

 inches high ; leaves opposite, sessile, divided into linear bristle-toothed or 

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