The New Zealand Plant Conservation Network

Species

Rytidosperma horrens

Etymology

Rytidosperma: wrinkled seed

Current Conservation Status

2018 - Threatened - Nationally Critical

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2012 - At Risk - Naturally Uncommon
2009 - Data Deficient
2004 - Not Threatened

Qualifiers

2012 - DP, RR

Authority

Rytidosperma horrens Connor et Molloy

Family

Poaceae

Flora Category

Vascular - Native

Structural Class

Grasses

Synonyms

None

Distribution

Endemic. South Island, upper Maitland Catchment, Lake Ohau

Habitat

Subalpine (1200 m a.s.l.). Recorded from wet flushes and tarn margins where it is a sparse to locally common component of short, dense, vegetation.

Features

Diminutive, tufted, bright green tussock with persistent, stramineous leaves below shoots of 3-4 conspicuously divergent leaf blades. Branching intravaginal. Leaf-sheath 10-15 mm, glabrous, ridged, becoming stramineous; collar thickened, paler beneath sheath; apical tuft 0.5-1.5 mm, sparse. Ligule a very narrow row of hairs c.0.25 mm long. Leaf-blade 25-30 x 0.5 mm, ¡À terete; persistent, weakly disarticulating at ligule; glabrous below except keel hairy apically; upper surface with numerous small white prickles on nerves; margin glabrous. Culm to 120 mm, internodes 40-60 mm. Inflorescence racemose of 2-5, widely spaced, solitary, overlapping spikelets on very finely toothed pedicels 2-5 mm long, rachis very finely toothed. Spikelets 6-8 mm long, 3-5 florets in each; awns exserted. Glumes equal, ¡À ovate-acute 5-6 mm, glabrous, bright green centrally, margins hyaline sometimes tinged purple below, faintly toothed above, apex finely ciliate, nerves confluent; upper 5-nerved, lower 3-nerved, upper surface with abundant small, white hairs. Lemma 2 mm, bright green, 7-nerved, nerves anastomising below sinus; upper row of hairs only in marginal tufts, 0.75 mm, ¡Ý sinus, 0.5 mm, not reaching upper marginal tufts, other glabrous; lemma lobes 1.5-2.5 mm, ¡Ý lemma, abruptly produced into 1.0-1.5 mm long awns, reflexed from twisting column 1 mm. Callus 0.25 mm, rounded, marginal hair tufts 0.4-0.5 mm, hairs 1-2 = to lodicule; nerved, cuneate and lobed. Anthers 0.7-1.0 mm, yellow, apiculate, exserted. Ovary 0.5-0.8 mm, obovoid, stipitate, stigma-style 1.20-1.75 mm, exserted. Seed 1.40-1.50 x 0.75 mm, obovate.

Similar Taxa

Exact relationships to other New Zealand bristle grasses is unclear. It has many of the features of the rather obviously unrelated R. merum Connor et Edgar from which it is easily distinguished by its smaller size, and much shorter inflorescences which do not elongate. The laterla lemma lobes are 1.5-2.5 mm rather than 3-8 mm long, the central awn 1.5-2.5 mm rather than 6.5-14 mm, spaced 1 mm rather than 2.5-3.5 mm away from the twisting column.

Flowering

January

Flower Colours

Yellow

Fruiting

April

Propagation Technique

Has been cultivated, and flowered and set seed in Auckland and Lincoln. A small and unremarkable grass unlikely to prove popular in cultivation.

Threats

Recent (2009) surveys have found Rytidosperma horrens to be locally common over a large area west of Lake Ohau. In future listings this species is likely to be regarded as Naturally Uncommon.

Chromosome No.

2n = 24

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 31 Jul 2014