COMPOSITE. 291 



21. Aster. Rays numerous, almot always in a single series. Involucre imbricated. Style- 



appendages subulate or lanceolate, not long-bearded. Akenes mostly flattened. Pap- 

 pus simple, copious. 



22. Brachyactis. Rays very numerous and in more than one series, short. Involucre herba- 



ceous. Style-appendages lanceolate, naked. Akenes flattish. Pappus simple, copious, 

 longer than the corollas. 



23. Erigeron. Rays numerous, long and slender, or sometimes short, in one or more series. 



Involucre of numerous narrow and mostly equal scales, little imbricated, not herbaceous. 

 Style-appendages short and broad, mostly obtuse. Akenes small, flattened, commonly 

 with a nerve or rib at each margin, rarely with one or more on the faces. Pappus sim- 

 ple or double ; the outer when present of short bristles or chaffy scales ; the other of 

 capillary scabrous bristles as in Aster, but commonly scantier, in a single series, and 

 more fragile or deciduous. 



Subtribe II. CONYZE.&. Heads heterogamous but never radiate ; the pistillate flowers in 

 more than one series ; their corollas a mere filiform tube, much shorter than the style ; 

 the perfect flowers with tubular 4-5-toothed corollas, much fewer in the centre of 

 the disk. 



24. Conyza. Involucre campanulate, of many narrow scales. Akenes and pappus as Erigeron. 



Heads small : flowers yellowish or whitish. 



Subtribe III. BACCHARIDEjE. Heads discoid and homogamous, unisexual, dioecious ; the 

 pistillate and staminate flowers on different plants, the former with filiform corollas shorter 

 than the style. 



25. Baccharis. Involucre imbricated ; the scales dry, not herbaceous. Pappus of very copious 



and soft capillary bristles, less copious in the staminate flowers. 



TRIBE IV. INULOIDEjE. Heads discoid in all Californian genera, and heterogamous, or 

 only when dioecious homogamous, with the ordinary tubular regularly 4 - 5-toothed corol- 

 las, or commonly the pistillate flowers (which are exterior) with slender or filiform corollas. 

 Anthers sagittate at base, their auricles pointed or tailed, rarely only acute. Branches of 

 the style never tipped with appendages : sterile (hermaphrodite-sterile) flowers with style 

 commonly undivided. Leaves almost always alternate, but opposite in No. 30. 



Subtribe I. PLUCHEINE^E. Scales of the imbricated involucre (at least the outer ones) not 

 scarious. Receptacle not chaffy. Head many-flowered ; the pistillate flowers with veiy 

 slender or filiform truncate or minutely 2 - 3-toothed corollas, the hermaphrodite but often 

 sterile flowers few on the centre of the flat receptacle. Akenes not exserted. 



26. Pluchea. Involucre not white-woolly, its scales dry and thin. Pappus of fine capillary 



bristles ; their tips not enlarged. 



27. Tessaria. Involucre white-woolly, of coriaceous rather rigid scales. Pappus of the central 



flowers with thickened tips to the bristles. 



Subtribe II. ADENOCAULONE^E. Scales of the involucre herbaceous, few in a single 

 series. Receptacle not chaffy. Head few-flowered ; both pistillate and hermaphrodite- 

 sterile flowers with similar dilated tubular corollas ; the former rather fewer, and with en- 

 larged exserted akenes. 



28. Adenocaulon. Akenes club-shaped and several times longer than the involucre, beset with 



some stipitate glands : pappus none. 



Subtribe III. FILAGINE^E. Scales of the involucre mostly thin and scarious. Receptacle 

 with chaff (scales of various texture) subtending or enclosing the fertile flowers or akenes. 

 Pistillate flowers with filiform truncate or 2 - 3-toothed corollas. Low floccose-woolly 

 herbs with sessile and commonly glomerate small heads. 



* Akenes gibbous and compressed : corolla and style lateral : pappus none. 



29. Micropus. Fertile flowers few and in a single series on the short receptacle, included in 



the laterally compressed very gibbous scales of the receptacle, which are firm-coriaceous 

 or cartilaginous in fruit, strictly enveloping the akene. 



* * Akenes straight or slightly oblique : corolla and style terminal. 

 +- Chaff loosely enclosing at least the akenes : central flowers sterile. 



30. Psilocarphus. Fertile flowers numerous in several series on a globular receptacle, each in 



an obovate hooded-saccate turgid membranaceous and reticulated chaff. Pappus none. 

 Leaves mostly opposite. 



