2. Juglans nìgra Linnæus. Walnut. [Plate 21.] One of the largest and most valuable trees of the Indiana forest. Leaf-scars with the upper margin notched; leaves 3-7 dm. long, mature leaves glabrous above and pubescent beneath, leaflets, usually 11-23, almost sessile, ovate-lanceolate, 4-10 cm. long, finely serrate, long-pointed at apex; flowers in May or June; fruit ripens the first year, in September and October, globose to oblong, 5-8 cm. in diameter; nut variable, from subglobose to ovoid or elliptical, more or less rounded or pointed at the ends, 1.5-3.5 cm. through the widest diameter; kernel edible; wood heavy, hard, strong, rather coarse, heart wood dark brown, durable, works easily and takes a high polish.
Distribution.—Ontario south to the Gulf States and west to Texas and Nebraska. It was more or less frequent to common in all parts of Indiana in well drained rich soils.
Remarks.—This tree is frequently called black walnut. On account of the many excellent qualities of the wood, the walnut has been a choice timber tree from pioneer days to the present. It served the pioneer for rails, and in his buildings for sleepers, rafters, interior finish, furniture, etc. It soon sprung into commercial importance, and has been used for almost everything for which wood is used. Indiana and Ohio have furnished the greatest amount of walnut. The supply of lumber from old forest-grown trees has become so scarce that it is sought in old buildings, rail fences, old stumps and old furniture has been worked over. That the demand for walnut timber will not cease is assured; this should encourage land owners to grow this tree. It is adapted to a moist, rich, deep soil and will do well in such a habitat in all parts of the State. Where such land is set aside for forestry purposes, no better tree could be used for planting. Since the tree develops a long tap root which makes it difficult to transplant, it is recommended that the nuts be stratified in the fall, and the germinated nuts be planted in April or May. The foliage of the walnut is often attacked by the "tent caterpillar" which can be easily destroyed by burning about sun down when the larvæ collect in a bunch on or near the trunk of the tree. Since the nut of the walnut is of considerable commercial value, it is recommended that the walnut be planted along fences, about orchards and as one of the species in windbreaks.
Trees with hard, tight or scaly bark; leaflets alternate, odd-pinnate, glandular-dotted beneath; leaflets serrate, usually unequal at the base, the lateral sessile or nearly so, the terminal short-stalked, the lowest pair the smallest, upper pair and terminal the largest, bruised leaflets characteristically aromatic; staminate flowers in slender catkins, anthers hairy; pistillate flowers in small clusters; fruit a bony nut contained in a woody husk which separates more or less completely from the nut into four parts.
JUGLANS NIGRA Linnæus. Black Walnut. (× 1/2.)