FLOWERING PLANTS AND FERNS OF ARIZONA 749 



3. Nutlets smooth and shiny 4 . 



4. Corolla white: flowers in a terminal capitate cluster, rarely with 1 or 

 2 -::-all few-flowered lateral clusters in the upper leaf axils: leaves 



sparsely strigose, green 2. C. capitata. 



4. Corolla yellow: leaves usually more abundantly sti - - and paler 

 5. Inflorescence an elongate cylindric thyrse: nutlets lance-ovate, 



than l a 2 times as long as wide, usually only 1 developing, the 

 margin acute: calyx becoming 8 to 10 mm. long in fruit, with 

 abundant spreading bristles: pedicels slender, 2 to 4 mm. long: 



plant 10 to 30 cm. high 3. C. flava. 



5. Inflorescence consisting of a large terminal cluster, capitate in flower, 

 with 1 or more remote, at maturity frequently stalked, much 

 smaller, lateral clusters: nutlets broadly ovate, less than l x 2 times 

 as long as wide, all 4 of them usually maturing, the margin 

 narrowly winged: calyx becoming 8 to 14 mm. long in fruit, its 

 hairs not very conspicuous and commonly more or less appr- - 

 pedicels stout, usually 1 to 2 mm. long: plant 20 to 50 cm. high. 



4. C. COXFERTIFLORA. 



2. Corolla tube short, scarcely if at all surpassing the calvx: flowers not hetero- 

 styled 6 . 



6. Nutlets smooth and shiny, not compressed 5. C. jamesii. 



6. Nutlets rugose or tuberculate. strongly compressed 7 . 



7. Margin of the nutlets with a conspicuous papery wing: a coarse bristly 



biennial 40 to 100 cm. high 6. C. setosissima. 



7. Margin of the nutlets not winged, thickened or merely acute: plants 

 less than 40 cm. high 8 . 

 8. Plant biennial: stems from a coarse rosette crowning a short-lived 

 taproot: scorpioid cymes elongating and becoming 3 to 8 cm. 



long, loosely 6- to 10-flowered 7. C. vtbginensis. 



8. Plant perennial, with a persistent caudex; cymose branches short, 

 1 to 2.5 cm. long, more or less corymbose, 2- to 6-flowere : 

 9. Pedicels stout, at first 1 to 2 mm. long, becoming 2 to 4 mm. long 

 in fruit; calyx lobes oblong or oblong-lanceolate, 5 mm. long 

 or less, with inconspicuous pale bristles: nutlets about one and 

 one-half times as long as wide, ovate, asymmetric, the ventral 

 face prominently rugose; stems usually less than 10 cm. 



high 8. C. MODESTA. 



9. Pedicels slender, 3 to 5 mm. long, becoming 5 to 10 mm. long in 

 fruit: calyx lobes lance-linear, 5 to 8 mm. long in fruit, with 

 abundant, conspicuous, usually tawny bristles: nutlets about 

 twice as long as wide, weakly asymmetric, the ventral face 

 weakly rugose: stems usually 15 cm. or more high. 



9. C. HUMILIS. 



1. Plants slender, annual: Section Krynitzkia Q0). 



10. Calyx circumscissile at maturity: low herb with a compact inflorescence; 



flowers each with a foliaceous bract 10. C. ctbcttms* essa. 



10. Calyx not circumscissile '11). 



11. Gynobase protruding beyond the nutlets, bearing a sessile stigma on its 

 apex; root and base of the plant conspicuously charged with a purple 

 dye; a small slender dichotomous herb; flowers each with a foliaceous 



bract 11. C. micraxtha. 



11. Gynobase shorter than the nutlets; style developed; root or herbage only 

 very obscurely if at all charged with a purple dye; plant not conspicu- 

 ously dichotomous; flowers commonly all or in part bractless 12 . 

 12. Nutlets all smooth and shiny (13). 



13. Spikes bracteate; stems reddish; nutlet 1, axial; ovules 2. 



15. C. maritima. 

 13. Spikes bractless; stems green; nutlets 1 to 4; ovules 4 14 . 



14. Calyx broadly conic at base, densely appressed hispid-villous, 

 lacking conspicuous bristles; nutlets 1 to 3; style surpassed by 



the nutlets 12. C. gr acilis. 



14. Calyx rounded at base, hispid or hirsute, inconspicuously str - - 

 along the margin; nutlets 4; style about reaching the tips of the 

 nutlets 13. C. fexdleri. 



