The New Zealand Plant Conservation Network

Species

Corybas rivularis

Etymology

Corybas: helmet flower
rivularis: of streams

Current Conservation Status

2018 - At Risk - Naturally Uncommon

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 - Data Deficient
2009 - Data Deficient
2004 - Data Deficient

Authority

Corybas rivularis (A.Cunn.) Rchb.f.

Family

Orchidaceae

Flora Category

Vascular - Native

NVS Species Code

NEMRIV

Structural Class

Orchids

Synonyms

Acianthus rivularis A.Cunn., Corysanthes rivularis (Hook.f.) Hook.f., Nematoceras rivulare (A.Cunn.) Hook.f.

Distribution

Endemic. North Island. Northland and Taranaki probably elsewhere.

Habitat

Lowland. Confined to wet, shaded sites within tall indigenous forest. Usually found along stream sides (often within moss on stones and rocks within the stream bed), but also on seepages on cliff faces and within damp, mossy, dripping holes on talus slopes

Features

Colonial, terrestrial, tuberous, glabrous, late winter to summer-green herb. Tuberoids globose to ellipsoid on extended roots. Plant at flowering to 40 mm tall. Leaf solitary (rarely paired), fleshy, subsessile or with a short petiole 5-10 mm long; lamina 20-30 x 15-25 mm long, oval to orbicular, apiculate, rounded to cordate at base; dark green to yellow green, margins and sometimes whole of upper surface flecked with purple or red, underside silvery pellucid. Flower erect, mostly large for plant, (15)-20(-25) mm long, held well above leaf, mostly dark crimson black; peduncle short and stout, 2.5-3.5 mm long. Ovary 8.5-10.0 mm long, narrowly oblong to ellipsoid, yellow-green, erect or slightly curving forward over leaf; subtended by two unequal floral bracts, the smaller projecting toward leaf, 1.5-2.0 mm long, linear-subulate to lanceolate-subulate, terete, pale green to cream, spotted or flecked with crimson, the larger smaller than, equal to or exceeding the ovary, (2.5-)8.8(-11.0) mm long, lanceolate to linear-lanceolate, curved, deeply keeled and mostly closely sheathing ovary for about one third to half of length, apex acute, green, usually with purple or reddish striae or flecks. Dorsal sepal membranous, more or less equal to labellum length 15-20 mm long, greenish with purple-red crimson-black striate or flecks, lanceolate-acuminate, apex acute, erect then arched forwards, or downwards, very rarely upwards. Lateral sepals and petals subsimilar, 20-30 mm long, filiform, cream to yellow green more or less flecked with red, greatly exceeding the labellum, held well above leaf. Labellum conspicuous, dark crimson-black, auriculate at base,; labellum tube 1.5-3 mm long, erect at first then abruptly deflexed at c. 90 degrees and expanding into a gradually broadening lamina; lamina (15-)20(-25) x (6-)10(-16) mm, narrowly obtuse when flattened, upper margins sharply folded inwards, upper third to half more or less overlapping, lower surface spreading and deeply grooved; apex usually held well above leaf; margins initially entire, becoming erose to finely and irregularly denticulate on either side, and with a short to moderately long down-curved apiculus; apiculus not or only rarely touching leaf.

Similar Taxa

Corybas rivularis is a very variable and at least four forms occur within it that probably merit formal taxonomic recognition (Irwin 1994, 1996). Corybas rivularis was long confused with C. orbiculatus (e.g., Moore & Edgar 1970).

Flowering

October - November

Flower Colours

Black,Red / Pink

Fruiting

November - January

Propagation Technique

Difficult - should not be removed from the wild.

Threats

Probably qualifies for listing as Sparse. Corybas rivularis sens.str. does seem to be genuinely uncommon but not threatened. Other segregates from the species are now well known and are awaiting formal taxonomic recognition. Past uncertainy over the conservation status of C. rivularis was because of past uncertainity over the status of these forms.

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 16 Jan 2016