Flora of New Zealand Series

; Holotype: BM! R. Brown Broad Sound, 10 Sept. 1802.

Stoloniferous, often forming colonies stretching to 80-(160) m along sand dunes, with much-branched, knotted, rope-like, hard, creeping culms. Leaf-sheath coriaceous, strongly-nerved, silky-hairy. Ligule a minute ciliate rim, hairs very dense to 6 mm. Leaf-blade c. 30 cm, inrolled and c. 1.5 mm diam., coriaceous, strongly nerved, silky-villous. Culm 2.5-6 mm diam., internodes glabrous, silky-villous below inflorescence. Dioecious: ♂ inflorescence with numerous pedunculate racemes, 5-12 cm, bearing up to 15 silky-villous spikelets, and terminated by a short bristle c. 1 cm; raceme clusters subtended by spathaceous bracts ≤ raceme. ♂ spikelets 10 cm; glumes ≤ spikelet, 7-9-nerved; lemmas similar to glumes but less villous, 5-nerved; each floret with 2 emarginate lodicules 0.6 × 0.3 mm, and 3 pollen-filled anthers to 6 mm, at anthesis flexible on long filaments from open florets. ♀ inflorescence very conspicuous, globular, appearing spiny with strict bracts to 15 cm, disarticulating from culm at maturity and wheeling along sand; spikelets solitary, hidden at base of bract, 15-18 mm; glumes = spikelet, 5-7-nerved, silky-villous; lemmas shorter, less villous, rather chartaceous, 3-5-nerved; lower floret Ø, consisting of 2 lodicules, and 3 pollenless white, rudimentary anthers, 0.7-1 mm, on stout filaments, gynoecium 0; upper floret ♀, larger, with 2 lodicules c. 1 × 1 mm, and 3 stamens with stout filaments bearing white, pollenless anthers up to 1.5 mm; ovary 1.5-2 mm, stigma-styles 17-20 mm; caryopsis free, c. 4.5-5 × 2.5 mm; embryo 3 mm; hilum 0.75-1.0 mm, in a broad depression. 2 n = 18. Plate 5A.

N.: coastal throughout; S.: Nelson, Marlborough, early records from North Canterbury, near Christchurch and near Dunedin. Sand dunes, almost the sole component of foredunes at many sites in North Id; diminishing in South Id.

Indigenous.

Dioecism in Spinifex was discussed by Connor, H. E. N.Z. J. Bot. 22: 569-574 (1984); and Connor, H. E. Blumea 41: 445-454 (1996). Connor (1984 op. cit.) estimated sex forms in S. sericeus, finding that the frequency of ♂ and ♀ colonies is about equal; there were no significant differences in colony size between ♂ and ♀ plants except at Wanganui where males formed significantly larger colonies than females.

The most important indigenous sand binding grass in N.Z., S. sericeus was formerly referred to S. hirsutus Labill., but Craig, G. F. Nuytsia 5: 67-74 (1984), chose a West Australian specimen as type of S. hirsutus and reinstated S. sericeus for N.Z. and Australian plants.

Spinifex sericeus was recorded from Canterbury, South Id, by Armstrong, J. B. T.N.Z.I. 12: 355 (1880); there are specimens in the Armstrong Herbarium, CHBG 5408, 5409, but S. sericeus is no longer found in Canterbury. There is one specimen from Dunedin Buchanan undated (WELT 76473).