BUCKTHORN FAMILY 



477 



broadly obovate, entire, light green above, paler beneath with a microscopic to- 

 mentum and often obscurely quilted, 2 to 7 (or 10) lines long, on very short peti- 

 oles; umbels I/2 to 1 inch broad, borne on short spur-like branchlets; flowers white, 

 with sweetish odor; capsules globose or slightly oblong, 2^/2 to 3 lines long, with 

 3 short erect horns near the top. 



Dry exposed mountain slopes and ridges and semi-arid valleys, 300 to 4000 

 feet : throughout cismontane California, especially abundant in the inner Coast 

 Range and Sierra Nevada foothills, less common or infrequent in Southern Cali- 

 fornia. North to Oregon, south to Lower California. Mar.-May. 



Field note. — Ceanothus cuneatus is an important constituent of the chaparral association, 

 frequently dominating large areas. On the lower margins of the chaparral belt it often extends 

 out onto dry flats or hills which it colonizes with scattered individuals. In such areas it is often 

 the only woody species. After chaparral fires it crown-sprouts vigorously. The leaves of crown 

 sprouts are usually toothed or spiny-dentate, as are also the leaves of seedlings. In the case of 

 crown sprouts the leaves may occur in threes (Grouse Creek, Tulare Co., Jepson 4710). This 

 species also regenerates from roots exposed by landslips or in other ways. On account of the 

 bluish cast of the shrub (apart from the flower) it is called Blue Brush by settlers in the southern 

 Sierra Nevada. The flowers are only rarely bluish. As the lower opposite pairs of branches die, 

 the bark and wood tissue of the main trunk die above and below, forming more or less continuous 

 channels which in some cases eventually result in the longitudinal Assuring of the stem into 2, 3 

 or 4 separate trunks (cf. fig. 236.). 



a 



Fig. 236. Ceanothus cuneatus Nutt. In many shrubs of the open col- 

 onies in the Sierra Nevada foothills, lethal longitudinal channels are formed 

 below and above pairs of dying or dead decussate branches on the main stem. 

 These increase in length and deepen with age, so that eventually the living 

 tissue is separated into 4, 5 or 6 strands. With the decay of the duramen 

 a single axial stem may be replaced by 2, 3 or 4 distinct stems, a, cross sect, 

 of stem, showing the beginning of the channels; b, c, later stages (cf. Ma- 

 drono 1:190-192). This phenomenon is doubtless caused by some pathogenic 

 organism. 



Locs.— Coast Ranges: Yreka, Butler 497, 667; Forks of Salmon, sw. Siskiyou Co., Jepson; 

 Anderson, Shasta Co., Alice King; Winneshaw, w. Tehama Co., Jepson; Hettenshaw Valley, 

 Trinity Co., ace. Tracy; Buck Mt., Humboldt Co., ace. Tracy; Asa-Bean Ridge, ne. Mendocino 

 Co., Jepson; Low Gap, Mendocino Co., Jepson; Butts Canon, n. Napa Co., Jepson; Calistoga, e. 

 of, Jepson 13,987; Leesville, Colusa Co., Jepson 8964; Hoods Peak Range (w. of St. Helena), 

 Jepson 13,996; Howell Mt., Jepson 2447, 5313; Miller Canon, Vaca Mts., Jepson 13,992; Ken- 

 wood, Sonoma Co., Marie Chase; Mt. Diablo, Jepson 13,993 ; Cedar Mt., se. Alameda Co., Jepson; 

 Mt. Hamilton, Jepson 4204 ; Los Altos, Santa Clara Co., Jepson 9102 ; betw. Gilroy and Corralitos, 

 Santa Cruz Mts., Jepson 13,994; Aromas, San Benito Co., EicTcman ; Arroyo Seco, Santa Lucia 

 Mts., Jepson; San Antonio Creek, Santa Lucia Mts., Jepson; Hernandez Valley, s. San Benito 

 Co., Jepson 15,423; Waltham Creek, w. Fresno Co., Jepson; Parkfield, e. Monterey Co., Jepson; 

 Cantua Creek, sw. Fresno Co., S. C. Lillis. Sierra Nevada: Upper Fall River Valley, ne. Shasta 

 Co., Jepson; Old Cow Creek, Shasta Co., Jepson; Rough & Ready, Nevada Co., Jepson 13,989; 

 Gwin Mine, Calaveras Co., Jepson; Columbia, Jepson; Chinese Camp, Jepson; Hetch-Hetchy, 

 Jepson; Coulterville, Jepson; Wawona, Jepson; Rattlesnake Gulch, e. of Friant, Fresno Co., 

 Jepson; Watson's Spr., North Fork Kaweah, Jepson 578; Three Rivers, Jepson; Nelson, Middle 

 Tule River, Jepson 4868. Tehachapi Mts. : Rowen, Jepson 6737 ; Bear Mt., Jepson 7172. S. Cal.: 

 Sycamore Canon, Santa Inez Mts., Jepson; Mt. Gleason, San Gabriel Mts., Peirson 415; San 

 Bernardino, Parish; Mt. San Jacinto (Univ. Cal. Publ. Bot. 1:94); Campo, s. San Diego Co. 

 (Bull. N. Y. Bot. Gard. 6:415). 



Var. ramulosus Greene. Branchlets more numerous, the branches often much elongated; 

 leaves somewhat floceose-tomentose beneath. — Santa Cruz Mts.; Marin Co. to Napa Co. 



