Native to (or naturalized in) Oregon:
- Broadleaf deciduous tree, 50-75(125) ft, [15-23(38) m], long trunk, oval to round crown. Bark dark brown to grayish black, divided by deep, narrow furrows. Leaves alternate, large pinnate, 30-60 cm long, from 15-23 leaflets (occasionally as few as 11), terminal leaflet frequently missing, each leaflet 5-13 cm long, 2-5 cm wide, ovate-oblong to ovate-lanceolate, acuminate tip, rounded base, irregularly serrate, fragrant when crushed. Fruit (nut) spherical, glabrous light green (4-5 cm diam.), grainy surface. Pith of stem uniformly chambered.
- Sun. Prefers deep, rich, moist soils, tolerates drier soils but grows much more slowly. Extensive taproot and is difficult to transplant. Wood valuable. Difficult to garden under since J. nigra inhibits the growth of other plants. Some plants, however, tolerate this situation, including selected annuals, bulbs, and herbaceous perennials. Woody plants that can be grown under walnuts include, species of Clematis, Lonicera, Cotoneaster, and Spiraea, as well as Cydonia oblonga (Quince), Ribes sanguinium, and Rosa rugosa.
- Hardy to Zone 4 Native from Massachusetts to Florida, west to Minnesota and Texas. A well-know fruit (nut) predator.
- nigra: refers to the dark brown or black bark
- Oregon State Univ. campus: southeast of Magruder Hall (Vet. Med.)