Species

Corybas rotundifolius

Etymology

Corybas: helmet flower
rotundifolius: round leaf; from the Latin rotundus and folium

Common Name(s)

Helmet Orchid

Current Conservation Status

2012 - 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

2009 - At Risk - Naturally Uncommon
2004 - Sparse

Qualifiers

2012 - EF, Sp

Authority

Corybas rotundifolius (Hook.f.) Rchb.f.

Family

Orchidaceae

Flora Category

Vascular - Native

NVS Species Code

ANZROT

The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.

Structural Class

Orchids

Synonyms

Corysanthes matthewsii Cheeseman, Corysanthes rotundifolia (Hook.f.) Hook.f., Nematoceras rotundifolia Hook.f., the New Zealand plant has also been confused with the Australian Corybas unguiculatus (R.Br.) Reichb.f.; Anzybas rotundifolius (Hook.f.) D.L.Jones et M.A.Clem.

Distribution

Endemic. New Zealand: North Island from Te Paki to near the Manawatu Gorge (However, all recent records come from Te Paki south to the Warkworth area with one outlier at Opuatia, near Rangiriri) and recently (2007) discovered on Chatham and (2008) Great Barrier Island

Habitat

A species frequenting open though often heavily shaded sites overlying seasonally waterlogged soils. It is often found in deep drifts of leaf litter, particularly under kanuka (Kunzea ericoides (A.Rich.) Joy. Thomps. or in association with regenerating kauri (Agathis australis (D.Don) Lindl.) forest. In parts of Northland it is frequently found in gumland scrub, though usually in shaded sites, often in or along the sides of drains.

Features

Diminutive orchid forming small colonies of 2-6 plants within deep drifts of leaf litter on poorly drained ground usually under regenerating forest or within gum land scrub. Plants at flowering 15-35 mm tall. Stem erect. Leaf usually solitary (sometimes paired), 10-25 mm long, blue-green, green to dull green, sessile, broadly ovate, rarely pandurate. Floral bract 1, < ovary. Flower usually solitary (sometimes 2), conspicuous, aligned over leaf, and raised well above it. Perianth 8-10(-18) mm long, horizontal, drooping. Dorsal sepal cream to pale-white, spathulate from narrow arching claw, obtuse, hooded, distinctly shorter than labellum (rarely the same length), apex entire. Lateral sepals and petals linear 4-5(-8) mm long, white to yellow-white, more or less incurving and appressed to labellum. Labellum tubular, margins overlapping, entire, apex usually extending well beyond dorsal sepal; labellum faintly striped 2-6 times for entire length, maroon, otherwise basally blotched dark maroon-red, with the colour extending as a paler broad band toward the apex where it again darkens such that apex is usually dark maroon-red. Internal portion of labellum covered in prominent, retrorse, hair-like calli, forming a distinct band from the labellum mouth, along mid-line and nerves, reaching almost to the column.

Similar Taxa

Corybas carsei is similar but smaller. The dorsal sepal in this species is prominently cleft at the apex (hair-lipped). Corybas carsei has the labellum usually shorter than the dorsal sepal, while the internal hairlike inward facing labellar calli are more less prominent and extend along the mid-lines and nerves for about half the labellum length. Corybas carsei flowers from late winter to spring (end of August to November (peaking in early October)), and is exclusively known only from restiad bog habitats.

Flowering

(June-) July (- September)

Flower Colours

Cream,White

Fruiting

October - November

Propagation Technique

Difficult. Should not be removed from the wild.

Threats

Uncommon and rather sporadic in its occurrences. However it is a small, winter flowering species, so it is easily overlooked. Some accessible populations have suffered from plant collectors.

Chromosome No.

2n = 36

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Life Cycle and Dispersal

Minute seeds are wind dispersed (Thorsen et al., 2009).

Where To Buy

Not commercially available

TAXONOMIC NOTES

Considerable research is underway to investigate the validity of the segregate genera split from Corybas R.Br. by Jones et al. (2002). Whilst much of that work has yet to be published, on advice from Australian Orchidologists Peter Weston and Stephen Hopper (pers. comm., July 2011, November 2014), all of the segregate genera recognised for New Zealand by Jones et al. (2002) are returned to Corybas (see also Lyon 2014). 

Attribution

Fact Sheet prepared for NZPCN by P.J. de Lange 14 April 2007. Description adapted from Moore and Edgar (1970)

References and further reading

Jones, D.L.; Clements, M.A.; Sharma, I.K.; Mackenzie, A.M.; Molloy, B.P.J. 2002: Nomenclatural notes arising from studies into the Tribe Diurideae (Orchidaceae). The Orchadian 13: 437-468.

Lyon, S. P. 2014: Molecular systematics, biogeography, and mycorrhizal associations in the Acianthinae (Orchidaceae), with a focus on the genus Corybas. PhD Thesis, University of Wisconsin-Madison. USA.

Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.

 

This page last updated on 16 Jan 2016