Part 1, 1914] 



CARDUACEAE : HELENIEAE 



65 



1. C. artemisiaefolia. 



2. C. lacera. 



3. C. lanosa. 



4. C. glabriuscula. 



5. C. denudata. 



the flowers. Corollas yellow, white or flesh-colored; tube very short, often glandular; throat 



elongate, longer than the tube and (except in the marginal flowers of some species) almost 



cylindric; lobes lanceolate or ovate, erect or spreading. Achenes linear or nearly so, terete, 



oval in cross-section, or obscurely 4-angled, striate and pubescent, in the first two species 



considerably compressed and somewhat tapering downward. Pappus of 4-16 hyaline squa- 



mellae, sometimes equal and sometimes very unequal in length, those of the marginal flowers 



often much shorter, or in one species wanting and in another rudimentary. 



Type species, Chaenactis glabriuscula DC. 



Annuals. 



Achenes decidedly compressed, tapering below; plants scurfy when 

 young. (Acarphaea.) 

 Pappus wanting. 



Pappus present, of 8—10 lacerated squamellae. 

 Achenes sub terete, linear or nearly so; plants floccose when young; 

 pappus of 4 (rarely 5 or 6) principal merely erose squamellae, with 

 or without 1-4 shorter external ones. (EuchaenacTis.) 

 Corollas yellow. 



Squamellae 4 or 5, without outer smaller squamellae. 



Bracts broadly linear; marginal flowers with decidedly 

 enlarged throat and limb, the latter palmately 5-lobed 

 (less marked in C. lanosa). 

 Stem branching at the base only; peduncles elongate, 



the earlier scape-like; plant decidedly floccose. 

 Stem mostly branched above, leafy; peduncles shorter, 

 never scape-like; plant sparingly floccose. 

 Bracts glabrate or glandular-granuliferous in age. 

 Bracts glandular -hispidulous. 

 Bracts narrowly linear; marginal flowers With slightly en- 

 larged throat and limb, merely obliquely 5-toothed. 

 Pappus of hyaline squamellae, at least 1 mm. long; plants 

 floccose when young. 

 Leaf -segments linear, not very fleshy. 



Pappus of the disk-flowers nearly as long as the 

 corolla, of lanceolate acute squamellae. 

 Plant tall and mostly simple below, soon 



glabrate. 

 Plant branched at the base and decidedly 

 floccose. 

 Pappus of all flowers less than one half as long as 

 the corolla, of oblong or obovate, obtuse squa- 

 mellae. 

 Leaf -segments very short and obtuse, crowded, fleshy. 

 Pappus of minute callous squamellae; plant not at all 

 floccose. 

 Squamellae 4 or 5, with some smaller ones outside. 



Plant erect, about 2 dm. high, leafy, conspicuously floccose; 



leaf -segments long. 

 Plant low, almost scapose, not conspicuously floccose; leaf- 

 segments short. 

 Corollas white or flesh-colored. 



Stamens partly exserted; bracts all appressed (except the very 

 tips in C. Xanthiana). 

 Involucral bracts acuminate; receptacle usually bristly. 



Heads broadly turbinate, often 1 cm. broad; squamellae 



of the central flowers half as long as the corollas. 

 Heads narrowly turbinate, 5—6 mm. broad; squamellae 

 all very short. 

 Involucral bracts obtuse or merely acute. 



Leaves bipinnatifid; involucres in age glandular-puberu- 

 lent. 

 Segments linear or filiform ; squamellae of the central 

 flowers as least two thirds as long as the corollas. 

 Segments oblong or short-linear; squamellae all very 

 short. 

 Leaves simply pinnate, with few linear divisions, or 

 simple. 

 Marginal flowers much enlarged ; squamellae equal or 

 nearly so. 

 Squamellae 4, rarely 5 or 6; plant rather simple, 

 erect; leaves, or their segments, linear-filiform. 

 Squamellae 10; plant low, diffusely branched; 

 leaves spatulate-linear, fleshy. 

 Marginal flowers scarcely enlarged ; bracts with some- 

 what foliaceous tips; principal squamellae 4 with 

 2-4 smaller outer ones. 



8. C. tenuifolia. 



9. C. aurea. 



10. C. gracilenta. 



11. C. Orcnttiana. 



12. C. Nevii. 



6. C. heterocarpha. 



7. C. tanacetifolia. 



13. C. carphoclinia. 



14. C. attenuata. 



15. C. stevioides. 



16. C. brachypappa. 



17. C. Fremontii. 



18. C. Cusickii. 



19. C. Xanthiana. 



