Flora of New Zealand Series

≡Orthopogon imbecillis R.Br. Prodr. 194  (1810)

≡Oplismenus imbecillis (R.Br.) Roem. et Schult., Syst. Veg. 2: 487 (1817)

≡Panicum imbecille (R.Br.) Trin., Gram. Icon. 2: t. 141 (1829)

≡Oplismenus hirtellus var. imbecillis (R.Br.) Fosberg et Sachet, Micronesica 18: 78 (1982)

≡O. hirtellus subsp. imbecillis (R.Br.) U.Scholzforma imbecillis, Phan. Monogr. 13: 127 (1981); 

Holotype: BM! Brown 6133 Australia, Port Jackson [fide Green, P. S. Fl. Australia 49: 480 (1994)].

Leaf-blade (0.8)-1.5-4 cm × 2-6 mm, narrow elliptic to ovate-lanceolate. Panicle (1)-2-9 cm; rachis of racemelets and longer spikelet clusters usually 1-4 mm, rarely longer. Spikelets up to 4 in small clusters and racemelets below, paired to solitary above or throughout rachis. Upper glume acute, mucronate, or with very short awn < 1 mm. 2 n = 54. Fig. 22.

N.: throughout; S.: Nelson (near Farewell Spit, D'Urville Id), Canterbury (one 19th Century collection); K., Three Kings Is. Open forest and forest clearings, second growth bush and coastal scrub.

Indigenous.

On Kermadec Is Oplismenus hirtellus subsp. hirtellus flowers mainly in winter and spring, whereas subsp. imbecillis flowers mainly in summer (Sykes and West 1996 op. cit. p. 457).

Also indigenous to South Pacific and Australia.

Once collected in Canterbury in late 19th Century (Banks Peninsula J. B. Armstrong CHR 5786 and CHBG 5451).

Oplismenus compositus (L.) P.Beauv. was recorded as naturalised on Kermadec Is [Cheeseman, T. F. T.N.Z.I. 20: 151-181 (1888); and also Sykes, W. R. N.Z. DSIR Bull. 219: 172 (1977), who at that time regarded both O. compositus and O. imbecillis as naturalised there]. Edgar, E. and Shand, J. E. N.Z. J. Bot. 25: 343-353 (1987) cited O. compositus in their checklist as native to Kermadec Is. All these records of O. compositus are now regarded as misidentifications for O. hirtellus (Sykes and West 1996 op. cit.).

Hekaterosachne elatior Steud., Syn. Pl. Glum. 1: 118 (1854) from "N. Zeeland", was referred to Oplismenus by Buchanan, J. Indig. Grasses N.Z. t. 11 (1878) and by Cheeseman (1906 op. cit. p. 849; 1925 op. cit. p. 141). Scholz (1981 op. cit. p. 185) considered that the original description of Hekaterosachne elatior was not that of a species of Oplismenus but Clayton and Renvoize (1986 op. cit. p. 127) equate it with O. hirtellus. No specimens have been seen.

Fig. 22 Oplismenus hirtellussubsp.imbecillis S, spikelet, × 12; G 1, G 2, glumes, × 24; L 1, lemma of lower Ø floret, × 24; L 2, lemma of upper ⚥ floret, × 24; P, palea dorsal view, × 24; Lo, lodicules, × 24; O, ovary, styles and stigmas, × 24; St, stamens, × 24. © All rights reserved. [Image: 4X7R]