COMPOSITES. 53 



20. XANTHOCEPHALUM. Heads many-flowered, pluWradiate. Involucre broadly 

 campaiiulate or heuiispherical. Receptacle flat or convex. Ligules usually elongated, 

 numerous. Akenes truncate and naked at summit, or edged with a ring bearing a minute 

 corouiform or scpiamellate pappus, or none. Heads larger, solitary at the end of the branch- 

 lets or in open cymes. 



21. GUTIERREZIA. Heads few-many -flowered. Involucre oMong-clavate or turbi- 

 nate to campauulate. Receptaide from plane to conical, connnonly alveolate or fimbrillate. 

 Style-appendages mostly slender. Ligules 1 to 8. Akenes short, obovate or oblong, terete 

 or 5-angled. ra2:)pus pluripaleacreous, but the paleiB often reduced to a crown or minute, in 

 the ray commonly smaller and sometimes wanting. Heads small, paniculate or cymose- 

 clustei'ed. Disk-liowers, or some of the central ones, occasionally infertile. 



22. AMPKIACHYRIS. Heads few-many-flowered; the ray-flowers only fertile; those 

 of the disk liermaphrodite or subhermaphrodite but infertile. Involucre, &c. of Guticrrezia. 

 Style-appendages lanceolate ; tlie stigmatie lines below them intlistinct or obsolete. Fertile 

 akenes pubescent. Pappus of the ray-flowers obsolete or coroniform, or of a few setiform 

 sciuamelUv ; of the disk setiform-paleaceous, viz. of 5 to 20 aristiform paleas or weak bristles 

 more or less dilated and united at base, nearly ecpialling the corolla. 



33. BRACHYCH^TA. Heads, &c. as in iioliihujo. Pajipus both in the ray and disk of 

 bristles abbreviated to squamella?. 



* t- Pappus pauciaristate, i. e. of few (less than 10) elongated awns or rigid bristles, some- 

 times caducous or wanting : heads radiate or in same genus rayless, solitary at the end 

 of the branches. 



23. GRINDELIA. Involucre many-flowered, hemispherical or at first gloliose ; its bracts 

 numerous and narrow, imbricated in many series, firm and rigid, with more or less herbaceous 

 tips. Style-appendages lanceolate or linear. Akenes short and thick, compressed or turgid, 

 or the outer triangular, truncate, glabrous. Pappus of 2 to 8 caducous nearly smooth awns 

 or corneous In-istles. 



24. PENTACH^TA. Involucre many-several-flowered, hcmisphei'ical or campauulate, of 

 thin and scarious-margined apprcssed bracts, destitute of herbaceous tips, commonl}^ tipped 

 with a delicate nmcro. Style-appendages filiform-subulate, hispid. Akenes oblong to fusi- 

 form-obo\ate, sonicAvhat compressed and villous. Pappus of mostly 5 (rarely 3 to 6 or 

 even 12) slender and persistent scabrous bristles with somewhat enlarged base, sometimes 

 reduced to this base, or even this obsolete. Receptacle short-alveolate. Rays either yellow, 

 or white or pink ! 



* -* * Pappus multisetose in either tlie disk or ray, but not in both, and akenes of disk 

 and ray unlike. 



25. BRADBURIA. Involucre campauulate, of rather broad and thin scariously margined and 

 mucronate-acuminate appressed bracts. Ray-flowers about 12, fertile; the style very short. 

 Disk-flowers about the same number, infertile ; their style-branches destitute of stigmatie 

 lines, filiform, barbellate-hispid. Akenes of the ray sparsely villous, trigonal-turbinate with 

 a strong rib at each angle ; the pap])us of numerous unequal rigid capillary bristles, little 

 longer tlian the akene : tliose of the disk abortive, with pappus of very few (usually 2) bristles 

 which are somewhat chaffy-dilated at base. 



26. HETEROTHECA. Involucre hemispherical or broadly campanulate, of narrow rather 

 rigid l)racts. Receptacle alveolate. Ray- and disk-flowers numerous, both fertile. Style- 

 branches of the hermaphrodite flowers ti|)ped with a lanceolate or sometimes (in the same 

 species ?) ovate-triangular appendage. Akenes of the ray thickish, often triangular, with no 

 pappus or an obsolete crown, rarely a bristle or two; of the disk compressed, serii-eous- 

 hirsute, and with a douljle pappus ; the inner of copious and long capillary scabrous bristles, 

 outer of numerous sliort and stout bristles or setiform S(]uamella!. 



* * * * Pappus multisetose and double, both in disk and (when present) in the ray; the 

 inner capillary; outer very short and sctulose or snuamellate. 



27- CHRYSOPSIS. Heads many-flowered, with rays numerous, or rarely wanting. In- 

 volucre campanulate or hemispherical, of narrow regularly imbricated bracts. Style- 

 apjicndagos from liucar-filiform to slender-subulate. Akenes compressed, hut often turgid, 

 from obovate to linear-fusiform. Principal pappus of numerous capillary scabrous bristles ; 



