Flora of New Zealand Series

walnut

Large tree to over 20 m high, with broad spreading crown. Shoots glabrous, stout, dark, with prominent, Y-shaped lf scars; buds grey, ± finely puberulent. Lvs to c. 55 cm long; petiole and rachis to c. 30 cm long on adult branches. Leaflets 5-9, densely glandular-puberulent when young, becoming glabrous except for axillary hair tufts on undersurface, entire; base cuneate to rounded; apex rounded to acute or cuspidate; lowest pair of leaflets much smaller; terminal leaflet largest. Lamina of terminal leaflet mostly 10-20 × 5-11 cm (sometimes larger on strong vegetative shoots), broad-elliptic or elliptic-obovate. ♂ catkins 5-11 cm long, puberulent. ♀ fls in clusters of 1-3, sessile or subsessile, densely glandular-puberulent; stigmas to 3 mm long, pale green. Fr. 3.5-5 cm long, subglobose, glabrous but gland-dotted, green, not beaked. Shell thick or thin, rugose; sutures thick and easily dividing in 1/2 at maturity. Seed very convoluted.

N.; S.: sporadic throughout.

S.E. Europe, E. to temperate Himalaya, China 1968

Spontaneous in the vicinity of parent trees, near old gardens and plantations.

FL Oct.

Walnuts or English walnuts were amongst the first nut plants introduced to N.Z. by early settlers from Europe, and several forms must have been brought in from France and Britain. They are now the most abundant and successfully cultivated edible nut and in many towns and cities the majority of large older gardens have at least one tree. There is considerable variation in the size of the nut and the shell thickness; wild or self-sown trees tend to have thick-shelled nuts.

In addition to the 2 spp. described here, the N. American black walnut, J. nigra L., is sometimes grown, especially in the Waikato. On the old embankments around the Tauranga Mission House in the Bay of Plenty there are many spontaneous saplings of black walnut. This is easily distinguished from J. regia by the serrulate lvs and the frs which are borne singly or few together as in J. regia, but have an irregular and ± sharply-ridged shell.