750 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



12. Nutlets all (or some of them) roughened (15). 



15. Calyx conspicuously recurving, most hirsute on the axial side; nutlet 



solitary, bent; ovules 2 14. C. recurvata. 



15. Calyx strict to spreading, not recurving, most hirsute on the abaxial 



side; nutlets straight (16). 



16. Nutlets distinctly heteromorphous, differing in size, frequently 



also in the markings and in the firmness of the attachment (17). 



17. Nutlets 2, one smooth and shiny, the other roughened; ovules 2; 



stems reddish 15. C. maritima. 



17. Nutlets 4, all more or less roughened; ovules 4; stems not red- 

 dish (18). 

 18. Odd nutlet abaxial; nutlets dark, with pale tubercula- 

 tions (19). 

 19. Plant shrubby, much branched, twiggy; inflorescence not 

 scorpioid, loosely racemose; flowers distant and not 

 2-ranked; pedicels frequently spreading, 1 to 6 mm. 



long _ 16. C. RACEMOSA. 



19. Plant herbaceous; inflorescence scorpioid, unilateral, the 

 crowded flowers 2-ranked; pedicels strict or ascending, 

 less than 1 mm. long (20). 

 20. Nutlets with merely angled margins; style reaching to or 

 only slightly beyond the tip of the odd nutlet; inflor- 

 escence naked, except near the base; plant usually 



prostrate or decumbent 17. C. angustifolia. 



20. Nutlets with narrowly winged margins; style coarse, 

 much surpassing the odd nutlet; inflorescence bearing 

 scattered minute bracts throughout; plant usually 



erect 18. C. inaequata. 



18. Odd nutlet axial; nutlets and tuberculations usually pale (21). 

 21. Consimilar nutlets winged; calyx lobes not noticeably 



thickened. 25. C. pterocarya. 



21. Consimilar nutlets not margined (22). 



22. Stems with spreading hairs; calyx with a short but dis- 

 tinct pedicel, evidently spreading or even recurving, 

 the base not gibbous on one side, the mature lobes 

 (particularly the axial one) usually much thickened 



and very conspicuous 19. C. crassisepala. 



22. Stems distinctly strigose; calyx sessile, strictly and closely 

 appressed to the rachis, gibbous on the axial side due 

 to a basal prolongation of the odd nutlet, the mature 

 lobes (particularly the axial ones) weakly and incon- 

 spicuously thickened 20. C. DUMETORUM. 



16. Nutlets homomorphous or practically so (23). 

 23. Style distinctly surpassing the nutlets (24) . 



24. Nutlets strongly bent above the base, glossy; gynobase nar- 

 rowly pyramidal 21. C. pusilla. 



24. Nutlets not bent, dull except in some forms of C. muricata (25) . 

 25. Groove of the nutlet replaced by a large more or less exca- 

 vated triangular areola occupying much of the ventral 

 surface of the nutlet; gynobase narrowly pyramidal; 

 nutlets thick, angulate, not margined. _ 22. C. albida. 

 25. Groove of the nutlet narrow; gynobase subulate (26). 

 26. Nutlets obscurely rugose, the back high-convex, the face 

 flat, the margin knifelike and inflexed. 



23. C. COSTATA. 

 26. Nutlets tuberculate or verrucose, not decidedly plano- 

 convex, the margin spreading, or none (27). 

 27. Margin of the nutlets merely angled, frequently thick- 

 ened; nutlets usually glossy and with the back ob- 

 tusely angled, the body ovate or triangular-ovate. 



27. C. muricata. 

 27. Margin of the nutlets more or less winged; nutlets with 

 a rounded back, the body lanceolate to narrowly 

 ovate (28). 



