374 ASTERACEAE. 



21. PLUCHEA Cass. 

 Herbs or shrubs with alternate leaves and small heads 

 of tubular flowers in terminal cymose clusters. Involu- 

 cral bracts imbricated in several series, appressed, her- 

 baceous. Receptacle flat. Outer flowers of the head 

 pistillate, their corollas filiform, 3-cleft or dentate. 

 Central flowers perfect, but mostly sterile, their corollas 

 5-cleft. Achenes small, 4-5-angled or sulcate. Pappus 

 a series of capillary scabrous bristles. 



1. P. sericea (Nutt.) Coville. (Arrowwood.) Shrub, 4 m. 

 high or less, with suberect slender willowy branches, very leafy 

 up to the cymose clusters of rather small heads; leaves silky-pubes- 

 cent, 2.5-5 cm. long, linear-lanceolate, acute at both ends, entire; 

 involucre campanulate; outer bracts ovate, obtuse, tomentose; 

 inner ones narrowly linear, deciduous; flowers whitish, tinged with 

 purple or red; pappus copious, the bristles of the sterile flowers 

 clavellate-dilated, of the fertile slender. (P. horealis Gray.) 



Rather common along the streams, especially in the interior 

 valleys. May-July. 



2. P. camphorata DC. Annual, stoutish, minutely and some- 

 what viscid-pubescent, leafy, 6 dm. high; leaves oblong-ovate to 

 oblong-lanceolate, acute at both ends, toothed or denticulate, the 

 larger 7-12 cm. long, petioled; heads short-pedicelled, dull purple, 

 crowded in a corymbose cluster; bracts ovate to lanceolate, often 

 colored. 



Occasional along streams and marshes about Los Angeles; Ballona 

 Creek. 



22. MICROPUS L. 



Low floccose annuals with alternate entire leaves and 

 several-flowered scattered heads. Pistillate flowers in 1 

 or 2 series on a small receptacle, each enclosed in a con- 

 duplicate bract which has a scarious appendiculate lip. 

 Hermaphrodite sterile flowers central, few, mostly naked. 

 Involucre outside of the fruiting bracts scanty and scari- 

 ous. Achenes gibbous, obovate, each enclosed in its 

 bract and falling away with it. Pappus none. 



1. M. californicus F. & M.' Slender, erect, 1-3 dm. high; leaves 

 mostly linear; fructiferous bracts 5-6, becoming firm-coriaceous, 

 somewhat semicordate or semiobovate in outline, straight anteriorly, 

 the soon erect bract-like tip mostly scarious. 



Freciuent on open hillsides in the Santa Monica Mountains and 

 in the foothills about Los Angeles. 



23. STYLOCLINE Nutt. 

 Low and diffuse white-woolly annuals, with alternate 

 leaves and terminal subglobose heads. Bracts of the 



