558 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



Key to the species 



1. Leaves opposite, the blades pinnately veined with several broad veins, not more 

 than 2.5 cm. long, thick, pilose or tomentulose at least on the lower surface 

 when young; stipules thick, commonly persistent (at least the lower por- 

 tion) ; inflorescences small, not or but little surpassing the leaves. 



1. C. GREGGII. 



1. Leaves alternate, the blades palmately 3-nerved; stipules thin, usually soon 

 deciduous except for the thickened basal scar (2). 

 2. Inflorescences terminal, elongate-thyrsoid, 5 to 15 cm. long, very many- 

 flowered, naked or nearly so, greatly surpassing the leaves; twigs not 

 rigid, glabrous or obscurely puberulent; leaf blades (the larger ones) 3 to 

 6 cm. long, glabrous or sparsely pilose on the veins beneath, bright green 

 above, somewhat paler beneath, broadly elliptic or ovate, the margins 



entire or very nearly so 2. C. integerrimus. 



2. Inflorescences mostly axillary, cymose or subracemose, not more than 4 cm. 



long, relatively few-flowered, commonly leafy; twigs rigid, copiously 



pubescent or puberulent; leaf blades commonly less than 3 cm. long (3). 



3. Plant unarmed; leaf blades thin, mostly suborbicular, broadly rounded at 



apex, commonly rounded or subcordate at base, not more than 1)4 



times as long as wide, with commonly denticulate or serrulate margins, 



not whitish beneath, puberulent then glabrate, the veins not prominent 



beneath 3. C. martini. 



3. Plant usually spiny; leaf blades thickish, narrowly to broadly elliptic 

 (rarely suborbicular), narrowed and obtuse or acute at apex, often 

 narrowed at base, usually at least twice as long as wide, with entire or 

 nearly entire margins, permanently pubescent, whitish and sericeous 

 tomentose beneath, the veins usually prominent beneath. 



4. C. FENDLERI. 



1. Ceanothus greggii A. Gray, PL Wright. 2: 28. 1853. 



Mohave County to Cochise and Pima Counties, 3,000 to 5,300 feet, 

 very common in chaparral, March to April (occasionally September). 

 Western Texas to southern California and northern Mexico. 



The plants are seldom more than 1.5 m. (5 feet) high, with petals 

 commonly whitish but frequently bluish or pinkish. Arizona specimens 

 vary greatly in pubescence and in the shape of the leaf blades. The 

 latter are commonly relatively short and broad (var. orbicularis Kelso), 

 but specimens from Fort Apache, the Chiricahua Mountains, and Rose- 

 mont (Pima County) have narrowly elliptic or oblanceolate, perma- 

 nently pubescent leaves. The blades are commonly entire or sparingly 

 denticulate, but specimens with some of the leaves spinose-dentate, 

 thus approaching C. perplexans Trel., have been collected at Hack- 

 berry (Mohave County) and near Fort Verde (Yavapai County). It 

 is suggested in a recent publication 82 that the Arizona specimens may 

 not belong to C. greggii, but partly to C. vestitus Greene and partly to 

 C. cuneatus (Hook.) Nutt., or some related form. ) 



2. Ceanothus integerrimus Hook, and Arm, Bot. Beechey Voy. 329. 



1840. 



Ceanothus myrianthus Greene, Leaflets 1: 67. 1904. 

 Ceanothus mogollonicus Greene, ibid. 



Southern Coconino County to Cochise and Pima Counties, 3,500 

 to 6,700 feet, chaparral and open coniferous forest, preferring shade, 

 May to October, type of C. myrianthus from near Fort Huachuca 

 {Palmer in 1890). New Mexico and Arizona to Oregon and California. 



«2 Howell, John Thomas, studies in ceanothus m. Leaflets West. Bot. 2: 228-240. 1940. (See 



pp. 228-229, 234.) 



