Tetradymia. COMPOSIT.K. 407 



The American species are of the Xurdnsmia section, with more corymbose heads and decided 

 rays. The few species of the group are very nearly related : the most southern one, and the only 

 one found in California, is the following." But P. sagittala (Xardosmia, Hook.), of the Rocky 

 Mountains, may possibly occur. 



1. P. palmata. Clothed with loose cottony wool when young, becoming gla- 

 brous with age : leaves rounded in outline, very deeply 5-7-cleft, the lubes im-i.^-ly 

 toothed or lulled: flowers dull white, deliciously scented : rays in the sterile heads 

 oblong and conspicuous, in the fertile ones narrow and shorter than their style. — 

 TussUago palmata, Ait. Kew. ed. L, iii. 188, t. 2. Sanlusmia palmata, Hook. 



Damp woodlands, from San Francisco northward. Also in Oregon and sparingly to New Eng- 

 land and Labrador. 



98. TETRADYMIA, DC. 



Head 4-9- (rarely 18-) flowered, homogamous ; the flowers all tubular and per- 

 fect. Involucre cylindrical or rarely campanulate ; its scales 4, 5, or sometimes 

 more numerous, oblong or narrower, rather rigid, more or less concave and carinate, 

 nearly equal, in one or two series, and rarely with short external ones at the base. 

 Receptacle small, flat or nearly so. Corolla with a slender tube, abruptly dilated 

 into a 5-parted limb ; the lobes linear or lanceolate, traversed by a more or less 

 evident mid-nerve. Anthers exserted, linear, mueronately sagittate, the auricles 

 connate. Style-branches with minutely penicillate apex tipped with a very short 

 and obtuse or sometimes more conspicuous and acute cone. Akenes terete, oblong 

 or somewhat fusiform, obscurely 5-nerved, long-villous or glabrous. Pappus of 

 copious fine and soft capillary scabrous bristles. — Low and much branched shrubs 

 (of the interior arid region, mainly between the Sierra and the Rocky Mountains) ; 

 with alternate linear or subulate entire leaves, and corymbose or racemose clusters 

 of middle-sized heads: corollas yellow. — DC. Prodr. vi. 240; Gray, Proc. Am. 

 Acad. ix. 207. 



In the paper above cited, the genus is extended so as to include an ambiguous species, con- 

 stituting the third section. 



§ 1. White-woolly, except the small terete fascicled leaves in the arils of the primary 

 leaves converted into spines: involucre of 5 or G scales, ."i - V-fiom ,-, <l : bristles 

 of t/t. pappus in a single series, a/must equalled and concealed by tht finer but 

 similar pappus-like long white hairs which densely cloth tin aJcene ! — Lago- 

 thamntjs, Torr. & Cray. (Lagothamnus, Xutt.) 



1. T. spinosa, Book. & Am. From 2 to 1 feet high, with rigid divaricate 

 branches, clothed with dense white wool and armed with sharp slender sph 

 Leaves crowded in the fascicles, succulent, Linear or terete, glabrous (aboul •"■ Lines 

 Long), mostly shorter than the spines : heads racemose or scattered along the branches 

 (half an inch long), short-peduncled. — Lagothamnus microphyllus & L. ambiguus, 

 Nutt. 



t in borders of the State; San Bernadino Co., on Providence Mountains (Cooper), and 

 through the Nevada desert to LI. die. 



§ 2. White-woolly, m- sometimes almost glabratt : involucre of I or 5 concavt scales 

 containing four flmoers : bristles of tin pappus very copious: akenes either 

 very villous or in thi sami species glabratt or glabrous J — El n ik\uvmi\. 

 Torr. & I - 



2. T. canescens, DC. A fooi or two high, unarmed, silvery-tomentose : leaves 

 narrowly Linear, varying i" Linear-lanceolate or somewhat spatulate (and from an 



