Journal Number 109
August 2008

THE COLUMN

Pterostylis trifolia in the Ruahine's
By Eric Scanlen

Mike Lusk sent the Editor and the Column some pix on 8 November 2007. We thought they were either stumpy Pterostylis venosa or stumpy P. humilis. Obviously short stemmed from sun exposure (?) as Pterostylis are wont to be. It had erect lateral sepals, overtopping the galea just like P. humilis but a brown labellum with tawny tinges in the tepals and broad, obtuse leaves just like P. venosa. It was growing under the edges of the tangled leatherwood (Olearia colensoi) at ±1,000m altitude near Maharahara in the southern Ruahine's. There was some unresolved debate, then the matter was dropped.

The Column was hunting for references re Caladenia minor agg. in the journals in April 2008 whilst amending the index thereto, (for some reason!) when Vic Vercoe's 23 Dec 1997 B&W prints of Ruahine's Pterostylis venosa/humilis, figuratively jumped out of J73:28. This had to be Mike's orchid! Had another keen orchidologist taken photos of only stunted P. venosa? Not Pygmalion likely. Vic had got his from Tunupo and Rangiwahia Tracks out of Apiti and ±32k north of Maharahara Trig. In the captions, the Editor wasn't clear whether they were P. venosa or P. humilis - which sounds vaguely familiar.

The Editor's list of NZ orchids in J106:25 gave synonyms of P. venosa Col. as P. confertifolia Allan, 1926 and P. trifolia Col. 1899. The Historical Series had H.H. Allan's 1926 description, with no pix, on p100 of the Transactions, Part 1, but mostly in Latin. However, "Herba ±7cm alta" and "Folio 3... laminae 3-5cm longae, 1.5-2cm latae" didn't need a Latin scholar to equate plant height and the size of those three obtuse leaves. Allan's specimen came from the Ruahine's, near Apiti, all of which added up to them being the same as Mike's and Vic's pix.

T.F. Cheeseman had already lumped P. trifolia with P. venosa by 1926 so H.H. Allan ignored it before re-describing it as P. confertifolia. See what lumping does? Allan's type specimen sheet in CHR had been annotated P. venosa by Druce, and Dan Hatch had it, in the 1945 Transactions, as
P. humilis Rog. on advice from R.S. Rogers himself, but why? It all sounds too familiar, doesn't it?

P. trifolia Col. from the Ruahine's near Norsewood, also sounded like Mike's and Vic's pix from the description in Historical Series No. 1. Colenso admitted describing it from one withered specimen - which didn't help his cause - supplied by Mr A. Olsen. His 1896 description from two specimens of P. venosa, uncharacteristically has no comparison with, or even mention of P. trifolia, described by him only seven years earlier. He was 85 in 1896 which may account for his memory slipping.

Incidentally, Ian St George has long said that the Otago so called P. venosa is taller than the N.I plant and lacks the cordate stigma. This definitely wants looking into by dedicated mainland orchidologists.

The lack of Latin diagnoses with Colenso's descriptions, allied with his type specimens usually going to Kew, probably accounted for most of his cherished species being put aside by Cheeseman, by H.H. Allan and subsequent chroniclers.

For whatever reason, P. trifolia was bumped from P. venosa pillar to P. humilis post but was never considered as a distinct species for 119 years! Now it is. Look at Mike's Fig. 13 (above) and ask yourself, how did this abbreviated orchid ever get lumped in with the figurative pillar and post?

Mike has sent the Column a highly detailed electronic pic of about 100 healthy Maharahara specimens in a tight colony, all abbreviated, consistent with the taxon and the climate at 1,000-1,200ms, its preferred altitude.

The AGM this year will be at Camp Wakarara. The Sunrise Track leads off into the Ruahine's thereabouts, only some 15k north of Vic's Rangiwahia site for P. trifolia Col., as the crow flies.

The hills there rise to a mere 1,500m. It should be a doddle locating this November-December flowering orchid; if it grows this far north. But Mike doubts it, having done this two hour climb to the Sunrise Hut several times. The leatherwood is only scattered this far north and he has yet to see this unusual orchid hereabouts. However, the weather will be clement, of course, so it will be worth another look with a now clued up field party won't it?

Acknowledgements: Many thanks for yet another revelation by Mike Lusk and to Ian St George for useful leads from the Colenso species but no thanks to successive orchidologists who have previously ignored P. trifolia/confertifolia into a century plus of ignominy.

Moral: Don't let discouragement from the experts put you off any unusual orchid finds. Hunt out the likely contenders in the Historical Series and the Journals then decide for yourselves if you have a new one or perhaps one that was long ago described then bumped, lumped or dumped.