SILVA OF NORTH AMERICA. 
CEANOTHUS SPINOSUS. 
Lilac. 
BRANCHLETS angled, spinescent. Inflorescence compound, on leafy branches. Leaves 
coriaceous, rarely 3-nerved, persistent. 
Ceanothus spinosus, Nuttall, Torrey & Gray Fl. N. Am. 411.— Parry, Proc. Davenport Acad. vy. 172. — Greene, 
i. 267 (1838). — Watson, Proc. Am. Acad. x. 337. — Garden and Forest, v. 447. —K. Brandegee, Proc. Cal. 
Brewer & Watson, Bot. Cal. i. 103. — Trelease, Proc. Acad. ser. 2, iv. 185 (excl. var. Palmeri). 
Cal. Acad. ser. 2,i1.109; Gray Syn. Fl. N. Am. i. pt. i. 
Usually shrubby in habit, Ceanothus spinosus in the canons of the San Rafael Mountains 
sometimes becomes a shapely tree, eighteen or twenty feet in height, with a stem five or six inches in 
diameter covered with dark red-brown bark roughened by small closely appressed scales, and upright 
branches forming an narrow open head. The branchlets are slender, divaricate, angled, pubescent or 
puberulous when they first appear, soon glabrous, bright green, ultimately reddish brown, and frequently 
end in sharp leafless thorn-like points. The leaves are elliptical, full and rounded and apiculate or often 
slightly emarginate or gradually narrowed and pointed or rarely three-lobed at the apex, rounded or 
cuneate at the base, villose-pubescent below when they first unfold along the stout midribs and obscure 
primary veins, soon glabrous, coriaceous, and persistent ; they are usually about an inch long and half 
an inch wide, and are borne on stout petioles which vary from one sixth to one third of an inch in 
length and, at first villose, finally become nearly glabrous. On vigorous shoots the leaves are sometimes 
ovate, conspicuously three-nerved, irregularly serrate, with incurved apiculate teeth, or coarsely dentate, 
and often an inch and a half long and five eighths of an inch wide. The stipules are minute, acute, and 
early deciduous. The flowers, which vary from light to dark blue and are very fragrant, open from 
March until May, and are produced in lax corymbs from the axils of acute pubescent red caducous 
bracts on upper leafy branchlets of the year, the whole inflorescence forming an open thyrsus often five 
or six inches long and three or four inches thick and destitute of leaves toward the apex. The fruit 
is depressed, obscurely lobed, crestless, black, and from one quarter to one third of an inch in diameter. 
Ceanothus spinosus is a common inhabitant of mountain cahons near the coast of southern 
California in Santa Barbara, Ventura, and Los Angeles counties, where it grows down nearly to the 
sea-level in forests composed of Quercus agrifolia, Platanus racemosa, Sambucus glauca, Umbellu- 
laria Californica, Alnus rhombifola, Juglans Californica, and often forms a heavy undergrowth 
with other small trees and many species of shrubs, its large clusters of bright blue flowers enlivening 
these forests for many weeks in early spring, when it is one of the most beautiful of all the members of 
this genus.’ 
Ceanothus spinosus was discovered in 1836 by Thomas Nuttall,’ near Santa Barbara, California.’ 
1 There appears to be no record of the introduction of Ceanothus 2 See ii. 34. 
spinosus into American or European gardens. 8 See Coville, Proc. Biol. Soc. Washington, xiii. 117. 
