460 



COMPOSITAE (COMPOSITE FAMILY) 



SPINY CLOTBUR 

 Xdnthium spinosum, L. 



Other English names: Spiny cocklebur, Thorny Burweed, Dagger- 

 weed, Dagger Coeklebur, Bathurst Bur. 



Introduced. Annual. Propagates by seeds. 



Time of bloom: July to September. 



Seed-time: September to November. 



Range: Ontario to Florida, westward to Illinois, Missouri, and 

 Texas. Also abundant on the Pacific Coast. 



Habitat: Warm, moist soil ; invades almost any crop. 



A very pernicious weed which came to us from tropical America. 

 It is sometimes cultivated for the odd appearance of its white-veined, 

 white-lined, dark green leaves, yellow 

 spines, and green burs. But these last, 

 with their hooked spines, are so easily 

 transported on clothing and by animals 

 that the plant should be considered an 

 undesirable resident of any neighborhood, 

 particularly as the fruits retain their 

 vitality for years, biding the time when 

 some stirring of the soil shall furnish 

 them the needed warmth and moisture 

 for germination. It is a worse weed than 

 the other Cockleburs, for it spreads as 

 freely in sod lands as elsewhere. (Fig. 

 321.) 



Stem one to three feet tall, many- 

 branched and hoary with whitish hairs. 

 Leaves alternate, two to five inches long, 

 lance-shaped, long-pointed, and narrow- 

 ing to short petioles, the lower ones lobed 

 and the upper ones entire, white-woolly 



Fl ?^ 32 V~ Spiny Clot " underneath and on midribs and veins 

 above. Just below each leaf is a slen- 

 der, yellow, three-pronged spine about an 

 inch long. Flowers of two kinds, the staminate ones in short 

 terminal spikes, the heads very small and greenish, like the 

 Ragweed. Fertile flowers in the axils below, consisting of a 



bur (Xanthiu 

 xi. 



