Flora of New Zealand Series

black wattle

Shrub to large tree; twigs ribbed or somewhat angled, tomentulose. Lvs 2-pinnate, alternate, tomentulose on rachis and undersurface of pinnules; pinnae in 9-18 pairs; pinnules in (20)-35-55-(60) pairs, close set, dark green, oblong, obtuse, entire, 1.5-3-(4) × c. 0.5 mm; petiole 15-25 mm long; stipules minute; solitary glands present between each pair of pinnae including basal pair, and 0-2 additional, often smaller, glands present in all lvs between the pairs of pinnae and often on petiole (sometimes glands irregularly distributed with respect to pinnae but always more than number of pinnae pairs). Infl. of numerous, many-flowered, pale creamy yellow, globose heads arranged in axillary, simple or compound racemes ± = lvs. Fls 5-merous, sessile. Pod puberulent, straight or somewhat curved, 30-90 × 4-7 mm; aril scarcely folded, thickened at base to one side of seed.

N.: locally common N. of Hamilton and from Bay of Plenty to East Cape, also established at Mohaka R. (Hawke's Bay), near Palmerston North and on the W. coast N. of Wellington; S.: Upper Moutere (Nelson), Brancott Valley (Marlborough), Head of Lyttelton Harbour (Banks Peninsula).

S.E. Australia, Tasmania 1980

Waste places, scrubland, pasture, riverbanks.

FL Sep-Nov.

The more numerous glands and the tomentulose stems distinguish black wattle from R. dealbatum. Seedling lvs have fewer pinnae, fewer pinnules and only a few, irregularly distributed glands. Large areas of Waikato were planted in R. mearnsii in the late 19th and early 20th centuries for bark to be used in tanning [ see Sherry, S. P., The Black Wattle (1971)]. Early records of naturalised plants of Acacia decurrens var. mollis probably refer to R. mearnsii escaped from these plantings. The sp. has also been referred to in N.Z. as Acacia mearnsii.