COMPOSITE FAMILY. 



179 



STAMINATE FL. numerous in subglobose heads ; scales of the involucre 

 distinct, in a single series. Corolla tubular, clavate, somewhat hairy. 

 Anthers connivent but distinct. Style abortive, undivided. Receptacle 

 oblong, terete, chaffy. PISTILLATE FL. 2, inclosed in a 2-celIed oblong 

 coriaceous closed involucre, which is armed with hooked prickles and 

 terminated by 1 - 2 stout beaks, ('orolla filiform. Akenes solitary in 

 each cell of the involucre, oblong, flat. Annual herbs. Leaves alter- 

 nate, lobed or dentate. 



1. X. struma'riinn, L. Leaves broad-ovate, mostly somewhat 3- lobed 



dentate, unarmed at base ; involucre of the fruit oval, with 2 straight 



beaks. 



SCROPHULOUS XANTHIUM. 



Clot-bur. Cockle-bur. 



Fr. Lampourde. Germ. Die 

 Spitzklette. Span. Lampazo 

 pequeno. 



Stem 1-3 feet high, roughish-pu- 

 bescent, branching. Leaves 3-6 in- 

 ches in length, andnearly as wide as 

 long, subcordate at base, but cun- 

 eately produced at the union of the 3 

 principal nerves. Heads of flowers 

 in axillary clusters. Involucre of the 

 fruit persistent, becoming an oblong 

 bur, with rigid uncinate prickles. 



Road-sides and waste places : 

 Northern and Middle States : intro- 

 duced ? Fl. August September. 

 Fr. October 



Obs. This has the appear- 

 ance of a naturalized strang- 

 er, but is considered by Gray 

 as indigenous ; it is an obnox- 

 ious weed, though not much 

 inclined to spread ; and with 

 a little attention, is easily 

 kept in subjection. The burs 

 are a great annoyance in the 

 fleeces of sheep. The var. 

 echina'tum, has the fruit 

 more prickly with the beak 

 incurved. 



AM. 



2. X. SPINO'SUM, Li. Leaves ovate-lanceolate, entire or somewhat 



Fro. 122. Branch of the Thorny Clot-bur (Xanthium spinosum) , showing the hooked 

 prickly, mature involucres. 



