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Journal Number 105
November 2007
THE COLUMN
Nematoceras "tricraig": Pollok to Glen Murray
By Eric Scanlen
The Column was working through the tedious Nematoceras trilobum aggregate, when something hit him, figuratively speaking, like a board in the face, causing yet another mental back-flip.
Plants tagged N. "tricraig", N. "trirex" and N. "trilowry" were apparently all the one taxon.
The first, from Pollok, 11 Aug 05, of fly's eggs' fame in Journal 98:34, the second, 15 Aug 05
from cousin Rex Blumhardt's forest farm at Klondyke Rd, west of Onewhero and the third,
28 Sep 05 from Lowry's farm at Glen Murray, 47km south of Pollok.
You may not have heard of the last two tags; the orchids were common at both sites and ancillary to our quarry, N. "Pollok" [J93:20] which was not found on these unpublicised field trips.
N. "tricraig" had variable colonies all around Craig's piece of cattle traversed bush and suspicion fell on N. "Pollok" some 40m away (where stock cannot reach them on a cliff) as being involved in hybridising; however, the gnat's eggs in N. "tricraig"'s labellum pocket, gave it enough interest for publication.
But N. "trirex" (Fig. 19) and N. "trilowry" (Fig. 21) two of the tedious N. trilobum taxa that seem to occur wherever one goes, got photographed only as a palliative to our disappointment for not finding N. "Pollok". |
Photos of the orchids in 3-D, when compared, caused the Column's board-in-the-face feeling and
basically established the August-September flowering N. "tricraig", as they are all now being dubbed,
as a taxon worthy of individual attention.
Bruce Irwin's outstanding drawings of N. trilobum specimens
in Woodland Rd, Katikati from 31 July 1987,
appear to be of the self same taxon. Just how widespread
is this iconic form of the species?
 Distinguishing features of N. "tricraig" include ±6mm wide flower (Fig.20 - right) and usually askew to the leaf, on a short ±3mm pedicel jutting out of the erect stem at ±60°. Peduncle and petiole
are variable in length depending on ground cover.
Leaf is trilobate, kidney shaped sometimes with undulate margins, floral bract is acuminate and green, secondary bract can be a mere bump or as long as the ovary and parallel with it, the tip being tucked under the labellum bib (Fig.20 - right).
The secondary bract is the incipient second flower so will no doubt
vary with the vigour of the plant. Lateral sepals 20-40mm, erect,
from 90° spread to parallel, lateral petals ±12mm outstretched
±level, all tinged with maroon.
Dorsal sepal is a deep, retuse to emarginate helmet, green but with purple veins showing in maturity.
Labellum has a cup shaped opening with in-curled ragged maroon margins and an arrow head apiculus in the usual Vee notched bib.
Green thickenings form the egg pocket in the channel with a small drain hole. The visible inner surface
to
the margin is adorned with short, white hairs, no doubt giving any pollinator a good foothold.
The midrib rises on a back lean, (Fig. 21) turns through ±300° at the first flexure then describes an S
bend to the apiculus touching the ovary. Typical of the genus, the pale green column lies back in its
very dark red surround, with colourless auricle vents narrowing slightly at the outlet and dropping
away
either side, tucked out of sight behind the labellum bib.
Preferred habitat is scrubby bush, near spur tops or in hollows. Rex had numbers on a spur-top track
in Pinus radiata but several colonies were in hollows in the native bush.
A closely related taxon is the undescribed N. "tribrive" [J84:23-26,29], this N. trilobum taxon is found
all around the Bridal Veil Falls, Te Mata and on Pukapuka Track in the Hunua Range. Its disjunct known
range, straddles to the east of the N. "tricraig" distribution so there is indubitably a close connection there.
But N. "tribrive" has a distinctive down sloping dorsal sepal, a double sized egg pocket and a normal short
to zero secondary bract protruding at ±60° to the pedicel. It would be interesting to see what form the
N. trilobum agg. take at Mt Pirongia or at Maungatautari. Any starters?
Acknowledgements
Thanks are due to Tricia and Wayne Aspin, Allan Ducker and to Stella Christoffersen for the Glen Murray
and Klondyke Rd. field trips and to James Lowry and Rex Blumhardt for welcoming us to their properties
for the N. "Pollok" hunt.
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