462 COMPOSITAE (COMPOSITE FAMILY) 
pair of strong, hooked beaks at the tip and a covering of hooked 
spines which enable them to cling to a garment or to the coats of 
animals for a ride to new homes. Each bur contains two “seeds,”” 
or achenes, oblong, flat, slightly ridged, with a tough, black coat, 
f or skin. It is believed that one 
of the pair germinates the first 
season and the other the next, 
thus assuring a two-years’ crop for 
one sowing. But the entire bur 
is also known to lie dormant in 
the soil for several years. Sev- 
eral other species of Clotbur are 
common and all are about as 
obnoxious as this one but none 
ranges so widely as X. canadense. 
(Fig. 322.) 
Means of control 
Hoe-cutting while the plants are 
small; or, if not too numerous, 
Fia. 322,—Clotbur (Xanthium hand-pulling before the burs are 
canadense). X t. formed. Put infested corn land to 
a grain crop, followed by clover or grass, the harvesting of any 
of which beheads ‘the weed before it has attained to much size or 
developed the burs. In its tender youth (three to eight inches in 
height) Clotbur can be killed by a spray of Iron sulfate or Copper 
sulfate. Plants on waste land or roadside which have been 
allowed to mature their burs should be cut and burned. 
BLACK-EYED SUSAN 
Rudbéckia hirta, L. 
Other English names: Yellow_Daisy, Golden Jerusalem, Darkey- 
“head, Nigger-head, Ox-eye Daisy. 
Native. Biennial. Propagates by seed. 
Time of bloom: June to October. 
Seed-time: July to November. 
Range: United States and Canadian Provinces east of the Rocky 
Mountains. 
Habitat: Prairies; meadows and pastures, waste places. 
