Trees , 5-18 m. Bark light to medium gray or brownish, divided into narrow checkered plates. Twigs with distal edge of leaf scar notched, glabrous or bordered by poorly defined velvety zone; pith brown. Terminal buds narrowly ovoid or conic, flattened, 4-7 mm. Leaves 18-38 cm; petiole 3-6 cm. Leaflets 9-15, lanceolate to lance-ovate, symmetric or falcate, 6.5-10.5 × 1.5-3.4 cm, margins serrate, apex narrowly acuminate; surfaces abaxially with capitate-glandular hairs, simple or 2-4-rayed fasciculate hairs, and often scales scattered over veins and blade, axils of proximal veins with prominent tufts of fasciculate hairs, adaxially with capitate-glandular hairs, sometimes also scattered fasciculate hairs, becoming glabrate except along major veins; terminal leaflet usually small or none. Staminate catkins 5-8 cm; stamens 20-40 per flower; pollen sacs 1.2-1.4 mm. Fruits 1-3, subglobose or short-ovoid, 2-3.5 cm, smooth, densely covered with capitate-glandular hairs and peltate scales, when very immature also fasciculate hairs; nuts globose to ovoid, 1.8-2.7 cm, deeply longitudinally grooved, surfaces between grooves smooth.

Flowering spring (Apr-May). Along streams and rocky canyon sides; 300-2100 m; Ariz., N.Mex., Okla., Tex.; Mexico (Chihuahua, Durango, Sinaloa, and Sonora).

Specimens intermediate between Juglans major and both J . microcarpa and J . nigra are discussed under the latter species.

Plant: tree; up to 15 m tall and 1.2 m in trunk diameter, sometimes with several trunks; STEMS when young dark to light brown, finely whitish glandular pubescent or puberulent, with prominent lenticels Leaves: 15-43 cm long; rachis finely whitish glandular-puberulent, rarely glabrous; leaflets 9-15(-17), serrate, opposite or alternate, sessile or short-stalked, oblong-lanceolate to ovate, (0.6-)2-3.5 cm wide and (2-)6-11.5(-13) cm long, the bases tapering and oblique, the apices acuminate; terminal leaflet usually smaller than lateral ones INFLORESCENCE: staminate and pistillate flowers in separate erect or pendant catkins or spikes Flowers: staminate catkins 7-17 cm long, slender, individual floral bracts small, whitish-tomentose; stamens 30-50; pistillate flowers 1-few, glandular-pubescent Fruit: FRUITS a drupe-like nut, with a fibrous, slightly fleshy husk derived from the involucre and calyx globose to oval, (1.9-)2.3-3.0 cm in diameter; husk thin, glandular-pubescent, inconspicuously verrucose; nut 1.8-2.8 cm in diameter, subglobose, slightly compressed, longitudinally striate, sometimes deeply so; SEED solitary, 2-lobed, with large, fleshy, oily cotyledons, lacking endosperm at maturity; often consumed as food Misc: Along mountain streams; 750-2150 m (2500-7000 ft) REFERENCES: Laferriere, Joseph E. 1994. Juglandaceae. J. Ariz. – Nev. Acad. Sci. Volume 27, 219.