BUCKTHORN FAMILY 65 



Ultimate branches rigidly divaricate and spinose; leaves evergreen, plane. 



Leaves 1-nerved and finely pinnate-veined; oblong-elliptic, bright green, entire; flowers blue. 



20. C. spinosus. 

 Leaves 3-nerved or in small-leaved forms, the lateral nerves obscure. 



Flowers blue; leaves abundantly glandular-serrate, glabrous above; branchlets pubescent. 



21. C. sorediatus. 



Flowers white; leaves mostly entire or on vigorous shoots, sparingly toothed, the teeth with or 

 without glands. 



Bark gray-green; rather compact erect shrubs; leaves ovate to oblong-ovate, mostly less than 



IS cm. long, glabrous. 22. C. leucodermis. 



Bark nearly white; widely spreading shrubs; leaves ovate to ovate-orbicular. 



Capsules smooth except for low crests; panicles usually simple; leaves mostly entire pale 



green on both surfaces and nearly or quite glabrous. 23. C. cordulatus. ' 



Capsules roughened with a thick exocarp; panicles usually compound. 



24. C. incanus. 



Stipule-bases persistent, thick and corky; capsules usually with dorsal or apical horns; flowers umbellate- leaves 

 firm-coriaceous and persistent. (Section Cerastes) ' 



Leaves alternate; flowers white. 



Horns of the capsule dorsal and prominent; capsule 7-13 mm. in diameter; leaves narrowly obovate 



entire, cuneate. 25. C. mcgacarpus. 



Horns of the capsule minute or none; capsule about 4-7 mm. in diameter. 



Leaves entire, oblanceolate to broadly elliptic, usually alternate but sometimes some of them 



opposite. 26. C. insnlaris. 



Leaves usually denticulate, round-obovate to deltoid-obovate, all alternate. 



27. C. verrucosus. 

 Leaves opposite; flowers white or blue. 



Flowers normally white. 



Leaves with their margins more or less revolute, densely tomentose beneath. 



28. C. crassifoHus. 

 Leaves not revolute. 



Horns of the capsule dorsal (near the middle) and spreading, usually minute; leaves usually 

 toothed, not cuneate. 



Leaves grayish green above, densely tomentulose beneath, minutely denticulate or entire. 



29. C. vestitus. 



Leaves rather bright yellowish green, nearly or quite glabrous above, spinose-toothed all 

 around. 30. C. perplexans. 



Horns of the capsule near the apex, erect and slender. 

 Erect shrub 1-2 m. high. 



Leaves entire, cuneate at base. 31. C. cuneatus. 



Leaves mostly toothed, obtuse or rounded at base. 32. C. Ferrisiae. 



Prostrate shrub forming mats; leaves entire or with a few small teeth at the rounded or 

 truncate apex. iZ. C. fresnensis. 



Flowers normally blue, sometimes lavender or rarely nearly white. 



Fruiting capsules 4-5 mm. broad, their horns short or slender and the intermediate surface smooth 

 or nearly so, not crested. 



Leaves not spinulose-toothed, either entire or denticulate, plane not sinuate and holly-like. 

 Leaves entire or denticulate at the apex. 



Plants prostrate. (See also C. fresnensis.) 



Leaves oblanceolate to narrowly elliptic, less than 6 mm. broad, with 1-3 small 

 teeth at the apex. 34. C. pumilus. 



Leaves nearly orbicular, entire or with several minute teeth; flowers lavender to 

 nearly white. 35. C. ramulosus. 



Plants not prostrate. 



Branches mostly elongated and arched; leaves not crowded, entire or often few- 

 toothed above. 35. C. ramulosus. 



Branches usually straight and rigid; leaves crowded on short lateral branchlets, 

 mostly toothed and retuse at apex; flowers dark blue. 



36. C. rigidus. 

 Leaves denticulate nearly all around, rarely some leaves nearly entire; stipules prominent. 

 Plants prostrate or with lax divergent and arching stems and branches; leaves 15-30 

 mm. long. 37. C. gloriosus. 



Plants with stout rigid and erect stems; branches short and stiff; leaves 5-15 mm. 

 long. 38. C. Masonii. 



Leaves with sharp spinulose teeth at least at apex, often sinuate and holly-like. 

 Plants with erect or divergent and arched stems. 



Bark usually gray; leaves mostly less than 12 mm. long and 6 mm. broad, with 4-8 



coarse spinulose teeth. 39. C. sonomensis. 



Bark brown; leaves over 12 mm. long and 6 mm. wide. 



Leaves concave or trough-like above, the margins undulate; stems stout and rigid. 



40. C. pupureus. 

 Leaves usually plane, the margins rarely undulate; stems rather weak and 

 arching. 41. C. divergens. 



Plants prostrate or decumbent. 41. C. divergens, subsp. 



Fruiting capsules 7-9 mm. broad; horns prominent and wrinkled, and the surface between the horns 

 conspicuously wrinkled and crested or ridged. 

 Prostrate or decumbent shrub forming mats; leaves spinulose-dentate above, cuneate and entire 

 below. 42. C. prostratus. 



Erect or spreading shrubs, forming rounded clumps about 1 m. high or less; leaves toothed 

 all around. 



Leaves mostly plane, not deflexed, rather finely denticulate with 6-8 rather coarse teeth 

 on each side. 43. C. pinetorum. 



Leaves undulate and strongly spinose-toothed all around with 4-5 coarse spinose teeth on 

 each side. 44. C. Jepsonii. 



