Juglans californica
Juglans cinerea
California black walnut, Southern California black walnut, Southern California walnut
butternut, noyer cendré, noyer cerdr, white walnut
with distal edge of leaf scar notched, often shallowly so, glabrescent or bordered by poorly defined velvety patch;
pith brown.
with distal edge of leaf scar straight or nearly so, bordered by well-defined, tan-gray, velvety ridge;
pith dark brown.
15-24 cm;
petiole 2-5 cm.
30-60 cm;
petiole 3.5-12 cm.
(9-)11-15(-17), usually narrowly oblong-elliptic to lance-elliptic, occasionally lanceolate, symmetric or weakly falcate, 4.3-9.5 × 1.6-2.6 cm, margins finely serrate, apex rounded to acute;
surfaces abaxially without tufts of hair in vein axils, abaxially and adaxially glabrous with scales but no hairs, main veins glandular, often sparsely so, leaflets without nonglandular hairs (except for multiradiate hairs early in season);
terminal leaflet well developed.
(7-)11-17, ovate to lanceolate or oblong-lanceolate, ± symmetric, (2.5-)5-11(-17.5) × 1.5-6.5 cm, margins serrate, apex acuminate;
surfaces abaxially with abundant 4-8-rayed fasciculate hairs, scales, and sometimes capitate-glandular hairs, axils of proximal veins with prominent tufts of fasciculate hairs, adaxially with scattered fasciculate hairs or becoming glabrescent;
terminal leaflet present, usually large.
1-3, globose, 2.1-3.5 cm, smooth, at first glandular, with scattered scales, soon glabrescent;
nuts depressed-globose, 1.8-2.2(-2.5) cm, shallowly grooved, surface between grooves smooth.
3-5, ellipsoid to ovoid or cylindric, 4-8 cm, smooth, with dense capitate-glandular hairs;
nuts ellipsoid to subcylindric or ovoid, 3-6 cm, surface with ca. 8 high, narrow, longitudinal main ridges, with narrow, interrupted, longitudinal ridges or lamellae between main ridges.
buds ovoid to ellipsoid, somewhat flattened, 5-6 mm.
buds conic, flattened, 12-18 mm.
catkins 5-14 cm;
stamens 15-35 per flower;
pollen sacs 0.6-1 mm.
catkins 6-14 cm;
stamens 7-15 per flower;
pollen sacs 0.8-1.2 mm.
Juglans californica
Juglans cinerea
Juglans californica is the most distinctive western walnut, but some care must be taken in identifying it. The distinctive leaflet shape of J. californica is occasionally replicated by early-season leaves of other species. Furthermore, J. californica is distinctive in lacking simple and fasciculate hairs on the leaves, but like most other walnuts, multiradiate hairs are normally present on the young vegetative growth (stems, petioles, and midribs) in the spring. The hairs are usually deciduous early in the growing season. They have short (0.1-0.2 mm), crisped rays and are never clustered or especially associated with vein axils. The fasciculate hairs found in all of our other species (except sometimes J. microcarpa) are persistent, have longer (0.3-0.4 mm), straight rays, and are concentrated in clusters abaxially in the axils of the main lateral veins.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
The butternut canker is killing Juglans cinerea across its range. Because the trees do not root-sprout, the range is contracting.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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