COMPOSITE. (COMPOSITE FAMILY.) 137 



Tribe VI. HEIJENIOIDE.E. Disk-flowers hermaphrodite and fertile. Bracts of 

 the involucre not scarious. Differing chiefly from the last tribe in entire absence of 

 chaff. 



* Involucre of narrow equal erect bracts : ligules persistent and becoming papery on the 



usually striate-nerved akenes : herbage more or less white-woolly ; no oil-glands. 



47. Riddellia. Heads with 3 or 4 ray- and 5 to 12 disk-flowers, all fertile. Involucre of 



4 to 10 linear-oblong coriaceous woolly bracts, and a few smaller scarious ones within, 

 sometimes an additional narrow outer one. Receptacle small, flat. Ligules as broad 

 as long, abruptly contracted at base into a short tube, truncate and 2 to 3-lobed. 

 Disk-corollas with short externally glandular-bearded teeth. Pappus of 4 to' 6 hyaline 

 scales. 



* * Involucre of narrow equal erect bracts, in only one series : ray-flowers female or none, 



the ligule deciduous ; disk-corollas 4-toothed : akenes Hat, with only marginal nerves, 

 usually much ciliate : plants not floccose-tomentose, and witli no oil-glands. 



48. -Pericome. Head many-flowered, homogamous. Involucral bracts lightly connate by 



their edges into a campanulate cup. Disk-corollas with viscous-glandular tube and 

 much exserted anthers. Akenes strongly villous-ciliate. Pappus a lacerate-ciliate 

 crown, and sometimes a pair of short awns, one from each angle of the akeue. Yellow- 

 flowered, with long-acuminate leaves. 



* * * Involucre hardly at all imbricated, its bracts when broad nearly equal or in a single 



series : ligules not persistent : disk-flowers numerous, mostly with 5 teeth : akenes few- 

 nerved or angled, or more numerously striate-angled when turbinate or pyriform: no 

 oil-glands. 

 *- Receptacle flat or convex: akenes from linear to obpyramidal, mostly quadrangular, 



rarely 5-angled : flowers all fertile. 



++ Involucre mostly hemispherical ; the bracts from oblong or oval to broader, not colored 



or scarious-tipped. 



49. Erlophyllum. Involucre of one or sometimes two series of oblong permanently 



erect bracts, either distinct or sometimes partially united into a cup, at least in fruit 

 concave at centre, partially receiving the akenes. Beceptacle from convex or rarely 

 conical to plane. Ray-flowers usually with broad ligules, very rarely none. Akenes 

 narrow, from clavate-linear to cuneate-oblong, mostly 4-angled. Pappus of nerveless 

 and mostly pointless scales. Floccose-tomentose or rarely glabrate herbs. 



50. Eahia. Involucre hemispherical or obovate and lax or open in fruit ; the plane bracts 



distinct to and commonly narrower at the base, not embracing akenes. Receptacle 

 mostly flat. Female flowers with exserted ligules, or rareiy none. Akenes narrow, 

 quadrangular. Pappus of several scarious scales. Not floccose-tomentose. 

 «. «■ Involucre broadly campanulate or turbinate ; its bracts from linear-lanceolate and 



spatulate to obovate or broader, at least the tips membranaceous and colored or 



petaloid. 



51. Hymenopappus. Involucre broadly campanulate ; its bracts 6 to 12, equal, obovate 



to broadly oblong, thin. Ray-flowers none. Corolla with reflexed or widely spread- 

 ing lobes. Akenes obpyramidal, 4 to 5-angled, with attenuate base, the faces 1 to 3- 

 nerved, the nerves at maturity sometimes as prominent as the angles. Pappus of 10 

 to 20 thin-scarious and mostly hyaline obtuse scales. 



52. Polypteris. Involucre from broadly campanulate to turbinate ; its bracts from spatu- 



late to linear-lanceolate, commonly in two series and equal. Rays in our species 

 evolute into a palmate ligule and fertile. Corolla of the disk-flowers with long lobes 

 Stamens wholly exserted. Akenes from linear and downwardly attenuate to clavate- 

 obpyramidal, 4-sided, minutely pubescent. Pappus of 6 to 12 equal hyaline-scarious 

 scales. 

 «. „ «• Involucre hemispherical or campanulate ; its bracts linear, erect, herbaceous to the 

 tip, inclined to embrace the akenes : heads discoid, or with an inconspicuous ligule. 



53. Chamactis. Receptacle flat. Akenes slender, linear-tetragonal or more compressed, 



pubescent Pappus of hyaline nerveless scales. Leaves mostly cleft or compound. 



