448 COMPOSITE. Tetradtmia. 



Dry plains of Lewis River, with the preceding, and on Ham's Fork of the 

 Colorado of the West; common, NuUall! July.— Shrub 2-3 feet high, 

 growing in tufts like a Furze. Spines sharp, spreading or recurved, half an 

 inch or a little more in length, as long as the fascicled leaves. Heads and 

 flowers nearly as in the preceding. 



§2. Involucre of b-Q scales, 5-9-Jlowered : the soft villoTis hairs which dense- 

 ly clothe the achenia as long as the less copious pappus ! — Lagothamnus, 

 Nutt. 



4. T. spinosa (Hook. & Am., I.e.): shrubby, much branched, decum- 

 bent ; the branches and scattered or racemose heads very woolly ; primary 

 leaves converted into acerose often recurved spines; the others fascicled in 

 their axils, very small, fleshy, linear, obtuse, glabrous. — Lagothamnus 

 microphyllus & L. ambiguus, Nutt. ! in trans. Amer. phil. soc. I. c. p. 416. 



Snake Country, on Lewis River, Mr. Tolmie. Arid plains with the pre- 

 ceding, common, Nuttall! July-Aug.— Shrub 3-4 feet high. Leaves usu- 

 ally much shorter than the spines, 2-3 lines long, somewhat terete, always 

 glabrous. Heads pretty large, on short jjeduncles, often nodding, most fre- 

 quently 5-flowered. Pappu^s of about 30 bristles, which are unequal as in 

 the preceding species, but are nearly concealed by the singular hairs of the 

 achenia, which perfectly simulate a pappus, and with which they were ap- 

 parently confounded by Hook. &f Am. I. c. These copious very white den- 

 ticulate hairs only differ from those of true Tetradymia by their greater 

 length, in this species nearly equalling the corolla and real pappus. 



165. CROCIDIUM. HooTc. fi. Bor.-Am. 1. p. 335, t. 118. 



Heads many-flowered, radiate ; the ray-flowers about 12, pistillate ; the 

 disk-flowers tubular, perfect. Scales of the involucre 8-12, oblong-ovate, 

 herbaceous, with somewhat scarious margins, spreading, nearly in a single 

 series. Receptacle oblong-conical, naked, papillose. Rays oblong; the 

 ligule with a short filiform tube : the corolla of the disk with a slender tube 

 and a campanulate 5-cleft limb ; the lobes spreading. Branches of the style 

 short; those of the ray very obtuse, nearly included in the tube ; of the disk 

 tipped with a flattened triangular appendage. Achenia obovoid-oblong, ob- 

 scurely 5-angled, canescent with somewhat caducous clavate-papilliform 

 hairs (which when moistened split from the apex into two valves, and emit 

 two attenuated spiral threads) ; those of the disk furnished with a deciduous 

 pappus of 15-20 strongly barbellate capillary bristles, rather shorter than the 

 corolla; of the ray similar, but destitute of pappus. — A small annual, send- 

 ing up numerous slender and mostly simple stems (a span high) from the 

 same root, which are naked above, and bear solitary heads. Leaves loosely 

 floccose-wooUy when very young, at length glabrous except in the axils, 

 which are lanigerous; the radical spatulate, somewhat toothed or incised; 

 the cauline linear, sessile. Corolla of the disk and ray somewhat deciduous, 

 bright yellow. 



C. multicaule (Hook. ! 1. c.)— iVu«. .' in trans. Amer. phil. soc. {n. ser.) 

 7. p. 441. 



