Flora of New Zealand Series

alder

Tree to c. 15 m high (to c. 20 m in cultivation). Bark dark brown, strongly fissured. Young shoots glabrous but glandular-viscid. Winter buds short-stalked, purplish. Petiole 7-15 mm long, often purplish. Lamina 4-10 × 2.5-10 cm (to 14 × 13 cm on vigorous vegetative shoots), broadly oblong to obovate, plicate in bud, hairy on veins beneath at first, soon glabrous except for tufts of axillary hairs, serrulate to coarsely serrate, lobulate on basal vegetative shoots; veins in 6-7 pairs, prominently raised beneath; base usually cuneate; apex rounded to retuse. Buds stipitate, not enclosing ♀ catkins in winter. ♂ catkins 3-8 together behind shoot apices, 2.5-7 cm long (to 12 cm in cultivation), cylindric, opening in spring before lvs; peduncles to c. 5 cm long; bracts peltate, purplish; anthers yellow. ♀ catkins 3-7 together behind shoot apices, c. 5 mm long, glandular. Cone (1)-1.3-1.7-(2) cm long, ellipsoid; scales becoming horizontal after dehiscence and persistent on tree. Nutlet c. 3 mm long, broadly ovoid; wing narrower than nut.

N.; S.: from the Waikato and Rotorua to Otago.

Europe, Asia, N. Africa 1914

Moist situations and along riversides, sometimes forming ± pure stands.

Alder has been widely planted in both North and South Is, especially in colder areas. Fruiting is prolific and in winter alders are very distinctive because of the abundance of developing catkins and the persistent woody cones. Several horticultural variants are grown but not found wild.