r 



100 University of California Publications in Botany. [VOL. 3 



TRIBE 3. INULEAE. EVERLASTING TRIBE. 

 27. PLUCHEA. Cass. 



Tall leafy herbs or shrubs. Heads numerous, clustered in 

 corymb-like terminal cymes, hemispheric, discoid, the numerous 

 flowers purplish. Marginal flowers of the head pistillate and 

 perfect, with tubular-filiform truncate entire or 2 or 3-toothed 

 corolla and slender 2-cleft style ; central flowers few, perfect, but 

 sometimes sterile, with tubular 5-cleft corolla (enlarged above) 

 and trifid or merely notched style. Involucre imbricated. Re- 

 ceptacle flat, naked. Achenes grooved. Pappus a single series 

 o'f capillary bristles. 



The genus Pluehea is here made to include two plants which 

 are very different in general appearance but which represent 

 two extremes of a genus in which the species are well united by 

 technical characters. Some botanists have attempted to force our 

 second species into the South American genus Tessaria, which 

 disposition of it is apparently favored by Hoffman, 18 who gives 

 as the range of that genus "Argentine to California.". Since 

 no other species of Tessaria ranges near California he probably 

 had T. borealis in mind. But Hoffmann distinguishes Tessaria 

 from Pluchea largely by the fewer (one to ten) hermaphrodite 

 flowers. Now, P. borealis often has, in California, at least, as 

 high as twenty hermaphrodite flowers, while in P. camphorata 

 a geuine Pluchea they are sometimes reduced to twelve. Since 

 also the involucral bracts in the two genera are quite similar it 

 is necessary, if both genera are to be retained, to fall back on 

 other characters, among which those proposed by Gray 19 may be 

 useful, namely, "the narrow heads and the long villosity of the 

 small receptacle" in Tessaria. This would restrict Tessaria to 

 South America and leave our second species in Pluchea, where it 

 undoubtedly belongs, unless a new genus based on habital char- 

 acters alone be erected for it. 



Herb : glandular-pubescent 1. P. camphorata. 



Shrub: herbage silvery with a close dense pubescence 2. P. sericea. 



Hoffmann, in Engler & Prantl, Natiirl. Pflanzenf. iv. abt. 5, 177 (1890). 

 . Am. Acad. xvii. 212 (1882). 



