COMPOSITE. 



ly annual coarse weeds, with opposite or alternate lobed or dissected 

 leaves, and inconspicuous greenish or whitish flowers. 



1. A. TRIFIDA, L. Great R<vj-v:ccd. 



Stem tall and stout; leasee 3-lobed serrate, the lobes oval-lanceolate, acuminata: 

 *acemes panioled :/n/#6-ribbed, the ribs terminating in as many crested tubercles 

 Tar.— intzgrifoua has all the leaves, or the upper ones, undivided, ovate or oval, 

 pointed. 



Low moist grounds, and banks of streams ; common. Aug. Stem 4 to 12 feet 

 1 i ,-h. s iiu r \ rough and hairy as well a ; th.> 'arge !e ver. Leaves ± to" inches broad, 

 opposite. Flowers obscure and unattractive, in long leafless spikes, axillary and 

 terminal. 



2. A. artemisjefolia, L. Roman Wormwood. Hon- 

 weed. Common Rag-weed* 



Stem slender, much branched hairy or roughish-pubescent ; leaves opposite, and 

 the upper alternate, twice pinnatifid, smoothish above, paler or hoary beneath ; 

 racemes or spiles loosely panicled; fruit obovoid globular, pointed, armed with 

 about 6 short teeth. — Yar. hetekophtlla, has the stem leaves pinnatifid, those of the 

 branches lanceolate. 



Waste places ; common everywhere. July — Sept. An extremely variable weed, 

 1'to 3 feet high, with finely cut leaves, embracing several nominal species. 



25. XAXTHIUal, Tourn. Cockle-burr. 



Gr. xanthus, yellow; in allusion to the color the plants are said to yield. 



Fertile and sterile flowers occupying different heads 

 on the same plant j the fertile clustered below ; the sterile in 

 short spikes or racemes above. Fertile involucre closed, 

 coriacious, ovoid or oblong, clothed with hooked prickles, so 

 as to form a rough burr, 2-called, 2-flowered, the flowers pis- 

 tillate, with a slender filiform corolla. Sterile involucre 

 sub-globose, many-flowered, with the scales in one series. 

 Achenia oblong, flat. — Low coarse annuals, with stout bran- 

 ching stems and alternate lobed or toothed petioled leaves. 



1. X. STRUMARIUM, L. Common Cockle-burr. Clot-weed. 



Stan unarmed, branching; leaves cordate, lobed, 3-veined, unequally serrate, 

 rough : fertile involucre oval, somewhat pubescent, the beaks straight. 



Roadsides and waste places: introduced. July — Sept. Stem bristly, spotted. 2 

 to 3 feet high. Leaves large, 3 to 6. Inches broad, on loag. stalks, iigi.1. FbrtOe 

 flowers in sessile axillary tufts. S'rile flowers few together, terminal, globular, 

 green. Fruit a hard 2-celled burr, near an inch long, covered with stiff hooked 

 prickles. 



2. X. SPINOSUM, L. Thorn Clot-burr. 



leaves ovate-lanceolate, pointed, wedge-shaped at the base, entire or slightly 3- 

 labed, minutely pubescent above, hoary underneath. 



Waste places: introduced. Sept. — >\~ov. Stem 1 to 3 feet high, armed with 3-par- 

 ted slender spurs. L-a>ys entire or repand-denticulate. Heads few, axillary, soli- 

 tary ; fertile in the lower and sterile in the upper axils. 



Tribe V. HELIAXTHE>£. The Sun-flower tribe. 



