Flora of New Zealand Series

R. tenue (Petrie) Connor et Edgar, N.Z. J. Bot. 17: 321 (1979)

≡Danthonia buchananii var. tenuis Petrie, T.N.Z.I. 46: 37 (1914)

≡Notodanthonia tenuis (Petrie) Zotov, N.Z. J. Bot. 1: 111 (1963); 

Lectotype: WELT 39920! D. P[etrie] Upper Waipori, Otago, Dec. 1893 (No. 1281 to Hackel) (designated by Zotov 1963 op. cit. p. 111).

Slender tufts, often with tufts of leaves at ends of elongating shoots, rooting at nodes; leaves < culms; branching extra- and intravaginal. Leaf-sheath light brown, usually with scattered long hairs, sometimes smooth; apical tuft of hairs to 2 mm. Ligule 0.2-0.3 mm. Leaf-blade to 15 cm, inrolled, mostly glabrous but margins slightly scabrid near base. Culm to 25 cm, internodes smooth but finely scabrid below inflorescence. Panicle erect, contracted, narrow, 1-7 cm, of few spikelets on short pedicels; rachis and pedicels uniformly closely short-scabrid. Spikelets 4-5-(6)-flowered, awns ± included by glumes. Glumes purplish centrally, lanceolate, subacute, 6-7.4 mm, ± equal, 5-nerved. Lemma c. 2 mm, 9-nerved, upper row of hairs dense, continuous, ≥ lemma lobes, lower row ± indistinct except for marginal tufts, elsewhere short scattered hairs; lobes 0.7-1.2 mm, tapering to minute awn or membranous; central awn 1.5-2.5 mm, column c. 0.5 mm, sometimes absent, < palea and upper lemma hairs. Palea c. 2.5 mm, ≤ upper lemma hairs, interkeel glabrous, margins with a few long hairs. Callus 0.2-0.3 mm, very short marginal hair tufts not, or a few just reaching lower row of lemma hairs. Rachilla c. 0.7-1 mm. Anthers 0.6-0.9 mm. Caryopsis not seen. Plate 12C.

S.: known only from Upper Waipori, Old Man Range, West Lake Mahinerangi, and Flagstaff Hill, Otago.

Endemic.

Connor, H. E. N.Z. J. Bot. 26: 163-167 (1988), reported that R. tenue seemed sterile and concluded that "the reproductive behaviour of the taxon does not inspire confidence for its future".

Only four specimens match Petrie's type from Upper Waipori: WELT 39938 D. Petrie Flagstaff Hill, 1908; OTA 219224 (duplicate CHR 155850) G. T. Daly West L. Mahinerangi, 1400 ft, 1966; CHR 518303 B. P. J. Molloy Rock and Pillar Range, 900 m, 1999; and CHR 149750 B. P. J. Molloy Old Man Range, c. 3000 ft, 1964. Two other sheets, one of R. gracile, CHR 3665, Rees Valley, collector unknown, the other R. buchananii, WELT 39945 D. Petrie 3094 Mt Ida, have pieces of R. tenue mounted on them, but because the sheets are mixed there is no certainty that the R. tenue was in fact collected from these localities.