404 COMPOSITE. 



1. A. bicolor, Hook. Bot. Misc. i. 19, t. 15 (1829). Stem 2 ft. high: 

 leaves ample, deltoid-cordate, coarsely sinuate-dentate or slightly lobed, 

 green above, white-cottony beneath: involucral bracts 4 or 5, in one 

 series, ovate, reflexed in fruit, small by the side of the 4 6 clavate 

 achenes. — Redwood forests of the Coast Range; also in the Sierra. 



Suborder 4- AMBRosiACEyE. 



Heads small, greenish, the fertile flowers without corolla, or this 

 reduced to an obscure rudiment. Rays none. Stamiuate involucres 

 mostly forming a raceme above the axillary and few pistillate ones. 

 Anthers but slightly united or quite distinct. Pappus none. 



Hints of tlie (lienera. 



Heads all alike, and only in the leaf-axils .--.--.- 43 



Staminate heads racemose above the others -------- 44, 45 



St aminate heads glomerate; fertile head becoming a bur - . _ . . 46 



43, IVA, Lhinxus. Perennial herb with simple mostly alternate 

 leaves, and discoid heads nodding on short pedicels in their axils. Invo- 

 lucre of few scales in 1 series, commonly joined into a cup. Marginal fl. 

 pistillate and with short tubular corolla; the other and more numerous 

 fl. staminate, with funnelform 5-lobed corolla and undivided style: 

 anthers nearly distinct. Receptacle with linear or spatulate scales sub- 

 tending the sterile fl. Achenes thick, naked. 



1. I. axillaris, Pursh, Fl. ii. 743 (1814). Branching sparingly, 1—1}4 

 ft. high: leaves from obovate and spatulate to broadly linear, sessile, 

 entire, 1 in. long or more: heads hemispherical: scales of involucre about 

 5, united at base, or beyond the middle. Var. pubescens, Gray. 

 Villous with loose spreading hairs; the involucre turbinate, almost 

 entire. — Solano Co. and southward, mostly on subsaline plains, or near 

 the coast. 



44. AMBROSIA, Tourneforl. Weedy aromatic coarse perennials with 

 mostly alternate and pinnately divided leaves. Flowers unisexual, the 

 staminate heads several-flowered and arranged in erect spikes or racemes 

 resembling aments. Pistillate heads mostly in the axils of the upper 

 leaves, 1 — 4-flowered, their involucres closed and achene-like, in maturity 

 bearing protuberances toward the summit. Achene ovoid or obovate, 

 thick. 



1. A. psiloslachya, DC. Prodr. v. 526 (1836). Stems erect, from 

 horizontal rootstoeks, 2 ft. high or more, with strigose pubescence and 



