Flora of New Zealand Series

arrow bamboo

Medium-sized and forming dense thickets; rhizomes running extensively from periphery. Culm 3-5 m, dark green; banded white just below nodes. Culm-sheath green or greenish purple, eventually very pale, internodes almost all hidden in lower and middle parts of culm; ligule 2-3 mm, broad and prominent, truncate. Branches 1 per node, sometimes 2-3 at upper nodes. Leaf-sheath glabrous, often purplish above. Ligule minutely puberulent. Leaf-blade (1)-3-5-(7) on each branch, to 25-(30) × 3.5-(4) cm, broadly linear or linear-oblong, abaxially upper ⅓ green and lower ⅔ glaucescent, adaxially shining dark green, acuminate. Inflorescence ± purple, at least on exposed side. Spikelets 4-9 cm, flattened; florets to c. 12, distichous. Glumes 2. Lemma 10-13 mm, including short awn, ciliate, obscurely tessellate. Fig. 1.

N.: North Auckland (Cavalli Is, Ruawai), Auckland, Waikato (especially Hamilton area), Bay of Plenty, Rotorua, Wanganui, Manawatu, Wellington area; S.: Nelson (especially Nelson City area), Buller, Westland (southwards to Hokitika), Marlborough and Canterbury (usually coastal). Roadsides, riverbanks, in or around plantations, especially near garden boundaries, in scrub and on forest margins, abandoned garden sites and waste places.

Naturalised from Japan, south Korea.

Pseudosasa japonica is by far the commonest and most widespread naturalised bamboo in N.Z. and has escaped from cultivation on the Volcanic Plateau and in most lowland areas southwards except in southern areas of the South Id. This roughly corresponds to its main regions of cultivation. Pseudosasa japonica is also the sp. most commonly known to flower, and flowered abundantly during the 1980s. The thickets do not usually die completely after flowering although large parts often do. Flowering continues for several years but viable seed seems to be uncommon and no regeneration from seed so far has been reported.

Fig. 1 Pseudosasa japonica I, inflorescence, × ½; S, spikelet, and St, stamens, × 3; G 1, G 2, glumes, × 4; L, lemma, × 4; P, palea dorsal view, × 4; Lo, lodicules, × 4; O, ovary, styles and stigmas, subtended by lodicules and anther filaments, × 10 © All rights reserved. [Image: 4X7C]