Scattered along streams and in canyons in the Edwards Plateau and Trans-Pecos 

 of Tex. to s.w. N.M. and cen. Ariz, and n. Mex. 

 The durable wood is used locally for posts. 



2. Juglans microcarpa Berl. River walnut, little walnut. 



Large shrub or small tree to about 6 m. high, rarely with trunk to 45 cm. in 

 diameter, the bark smoothish or lightly furrowed; branches usually arising near 

 the ground to form a broad rounded crown; twigs reddish-brown, densely hairy 

 when young, with age becoming ashy-gray; leaves to about 3 dm. long; leaflets 

 usually 17 to 23, sometimes fewer, essentially sessile, narrowly lanceolate, 

 tapering to an acuminate apex, more or less falcate, to 75 mm. long and 12 mm. 

 wide below middle, subentire to serrulate on margins, thin, yellowish-green, with 

 age becoming essentially hairless; fruit spherical, 1.2-2 cm. in diameter; husk 

 brownish, thin, hairy; nut with a thick hard shell and a small edible kernel. 

 /. rupestris Engelm. 



Scattered along streams and arroyos in s. and w. Tex. and w. Okla. to s.e. 

 N.M. and n. Mex. 



The var. Stewartii (I.M.Johnst.) W. Manning with broader leaflets and larger 

 fruits on the average, is reported to occur in the Chisos Mts. of Trans-Pecos 

 Texas. 



2. Carya Nutt. Hickory 



Trees with hard and very tough wood, and scaly buds from which in spring are 

 produced usually both kinds of flowers with staminate flowers below the leaves 

 and the pistillate flowers above; leaves petiolate, odd-pinnate, often glandular- 

 dotted; leaflets 5 to 25; staminate aments usually in fascicles of 3 in the axils 

 of bud scales; stamens 3 to 8, adnate to the bract and 2 bractlets; filaments short 

 or none, free; pistillate flowers 2 to 10 in a cluster or short spike on a peduncle 

 terminating the shoot of the season; bract and typically 3 bractlets sepal-like in 

 flower, a true calyx absent; stigmas sessile, 2 and sometimes divided, with a 

 stigmatic disk at their base, papillose, commisural (above the lines connecting the 

 carpels), usually persistent; fruit with a 4-valved firm and (at length) dry husk 

 that consists of the exocarp or involucre which usually falls away from the 

 smooth and crustaceous or bony nutshell or endocarp; nut incompletely 2-celled 

 and (at the base) mostly 4-celled. 



Probably about 15 species in eastern North America and eastern Asia. Because 

 of their tough, resilient wood some species are used for such purposes as the 

 making of tool handles. 



1. Bud scales valvate; bud scale scars wide, separate, not in a distinct ring; husk 

 sutures winged or keeled (2) 



1. Bud scales imbricate; bud scale scars in a distinct ring; husk sutures not 



winged nor keeled (5) 



2(1). Shell smooth; kernel sweet; cotyledons not deeply 2-cleft (3) 



2. Shell uneven; kernel bitter; cotyledons deeply 2-cleft (4) 



3(2). Leaflets 5 to 9; fascicles of staminate aments peduncled 



1. C. myristicaeformis. 



3. Leaflets more than 9; fascicles of staminate aments sessile or nearly so 



2. C. illinoinensis. 



4(2). Bud sulphur-yellow; husk wingless at base, at maturity splitting only to 

 just below middle; nut gray, smooth; leaflets usually fewer than 9, 

 the lower surface pubescent and with ferruginous scales; terminal 

 leaflet essentially sessile 3. C cordiformis. 



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