Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Juglans californica

Juglans hindsii

California black walnut, Southern California black walnut, Southern California walnut

Hinds' black walnut, northern California black walnut, northern California walnut
Habit Shrubs or small trees, to 6-9 m. Bark light or medium gray, divided into rough plates. Trees, 6-23 m. Bark light or medium gray, split into smooth or ± scaly plates.
Twigs

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 shallowly to deeply notched, not bordered by well-defined band of pubescence;

pith light brown.
Leaves

15-24 cm;

petiole 2-5 cm.

22-45 cm;

petiole 3-8 cm.
Leaflets

(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.

13-21, narrowly triangular to lanceolate, symmetric or weakly falcate, (5.6-)7.3-13 × (1-)1.9-2.8 cm, margins serrate, apex acuminate;

surfaces abaxially glabrous or with sparse glands, sparse glands and few capitate-glandular hairs scattered along major veins, fasciculate hairs conspicuously tufted in axils of proximal veins, sometimes also on adjacent blade and edges of midrib, adaxially glabrous or with scattered scales, major veins glabrous or with sparse scattering of glands and few capitate-glandular hairs, without nonglandular hairs;

terminal leaflet well developed.
Fruits

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.

1-2, globose, 3.5-5 cm;

nuts ovoid to ovoid-globose, 2.4-3.2 cm, smooth or nearly so or shallowly and indistinctly ridged or grooved.
Terminal

buds ovoid to ellipsoid, somewhat flattened, 5-6 mm.

buds ellipsoid to oblong, flattened, 6-8 mm.
Staminate

catkins 5-14 cm;

stamens 15-35 per flower;

pollen sacs 0.6-1 mm.

catkins 6-15 cm;

stamens 20-40 per flower;

pollen sacs 1-1.4 mm.

Juglans californica

Juglans hindsii
Phenology Flowering spring (Mar–May). Flowering spring (Apr–May).
Habitat Hillsides and canyons Along streams, sometimes on disturbed slopes
Elevation 30-900 m (100-3000 ft) 0-300 m (0-1000 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

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.

Before 1850, Juglans hindsii was restricted to a few locations (J. R. Griffin and W. B. Critchfield 1972). It has been widely used as a rootstock for grafting J. regia and has been planted extensively in many parts of California for this purpose. It is now naturalized in many areas where it apparently did not occur before the introduction of commercial walnut growing. Possibly some of these naturalized populations are introgressed with J. nigra, since spontaneous hybridization between J. hindsii and J. nigra has been reported in areas where both species have been planted. These hybrids are difficult to distinguish from J. hindsii unless fruit are present. Currently most commercial walnut orchards use hybrid rootstocks, usually J. hindsii × J. regia (G. H. McGranahan and P. B. Catlin 1987).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 3. FNA vol. 3.
Parent taxa Juglandaceae > Juglans Juglandaceae > Juglans
Sibling taxa
J. cinerea, J. hindsii, J. major, J. microcarpa, J. nigra
J. californica, J. cinerea, J. major, J. microcarpa, J. nigra
Synonyms J. californica var. hindsii
Name authority S. Watson: Proc. Amer. Acad. Arts 10: 349. (1875) Jepson ex R. E. Smith: Univ. Calif. Agric. Exp. Sta. Bull. 203: 27. (1909)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America, OregonFlora, UW Burke Herbarium

The species comparison tool is brought to you by:
Northwest Wildflowers