Journal Number 115
February 2010

THE COLUMN

Thelymitra "puriri" in Diggers Valley
By Eric Scanlen

Remember Ruth Renner's mauve/pink Thelymitra growing 1.2m above ground, in the nine year old puriri log at Diggers Valley? (J112:22,26) The Column thought then, that it was a pink form of RH Matthews' 1904 find [1], taken now to be T. "sansfimbria", found again recently by his great-great nephew Kevin. It is a blue, perfumed, un-striped form of T. pulchella with no fimbria on the column arms.

Well, Ruth's isn't that at all, according to Ruth's and Kevin's latest data:
A) it has no perfume,
B) it is blue/mauve, not blue,
C) the column is different with some short yellow fimbria on the column arms... and
D) it is growing in a mossy hole in a decaying puriri log, not a boggy piece of scrub.

The puriri hole dries out so Ruth has had to dribble a bit of water around when things have been hot and dry for long periods. Diggers Valley averages some 2,000mm of rainfall per annum which is wetter than most coastal climates. So Ruth chose the suggested tag-name of Thelymitra "puriri" then bought a new camera which incidentally has produced some superior images along with Kevin's as you can see in Figs. 35, 36, Inside Back Cover.

Fig 35 - Five flowers on T. "puriri" by Ruth Renner, 4 Nov. 2009, flowering on a hot sunny day. Probably a T. pulchella sibling but where are the stripes?		Fig 36 - Normal column on T. "puriri" by Ruth Renner, 4 Nov. 2009, showing its fimbriate column arms and its own granular pollen flopped behind, on top of and in front of its own stigma. Indications of Thrips/fall-back self pollination.

The orchid appears to be yet another form of the aggregate of natural, amphidiploid-hybrid,
T. pulchella with the split post anther lobe. This harks back to parent T. cyanea with its two yellow or white parts of the post anther lobe, like column arms but usually corkscrewing in opposite directions. The lack of T. cyanea's stripes, as in T. "sansfimbria", is surprising but was also reported by Thom Pendrigh from Oxford in N/L25:10, March 1988. So non-striped is a widespread trait but definitely rare for this aggregate.

Collecting info from Ruth, Kevin and their pix, the tallest flower is 55cm, its leaf is 38cm. Floral
bracts are a fleshy green and acute with square shoulders. The leaf sheathes the base of the
peduncle and there are two or three acute bracts sheathing the stem with up to eleven flowers.
The flowers, up to a measured 30mm diameter, open wide only in hot sunny weather during November. The photos show granular pollen which has fallen around its own stigma. One can thus surmise that T. "puriri" is also Thrips-fall-back-self pollinated. Some pix with the black Thelymitra Thrips in the flowers would be nice to confirm this hypothesis.

Amongst T. "puriri" plants with normally formed columns, the lower one only, on at least two stems, had a modest staminodium standing from the base. The Column has heard that this is a throw-back which occurs from time to time in several if not all the sun-orchids. This harks back million of years to that distant ancestor of orchids which had proper stamens. T. hatchii, in Ulrich Walthert's photos, on an old calendar of the Column's, show long staminodia standing right into the yellow cilia on the column arms, in all four open flowers. The Australian T. circumsepta was actually described from a type specimen with staminodia.

In T. "puriri", the staminodium on the lowest flower of at least two plants only out of nine, has to be most unusual. Can anyone explain?

The strictly local site of T. "puriri" is a conservation worry. Propagation is not the Column's forté but, some ground similar in make up, exposure and moisture content to that in the log should be good for transplanting a trial few of the seedlings provided some substrate is transferred too to ensure that the plant's mycorrhizal fungus goes too. Perhaps a good dose of rotting puriri would be of assistance in the circumstances.

The Column expects that the chromosome count will be 2n=66 as in T. pulchella [2] but, are the non-striped forms from a T. longifolia parent or one of the many forms of T. aff. longifolia or perhaps one of several other sun-orchids in the north with 2n=26 chromosomes?

Black Thrips happily fly in and out of closed sun-orchids and larger flies and native bees have been spotted on open Thelymitra. Whatever is responsible for this assumed hybrid, seems not to be selective as to species being visited and could easily have cross pollinated say T. aff. pauciflora with T. cyanea.

All the reader has to do to check, is cross pollinate a range of 2n=26 chromosome Thelymitra with different forms of T. cyanea to see what the seeds produce. Getting the chromosomes to double up and thus produce the necessary amphidiploids could be a minor problem but should be well within the abilities of dedicated propagators with five or so years to spare! Any takers?

References
1. Scanlen E.A., Matthews & Son on Orchids, NZNOG Historic Series 2006
2. Dawson, M.I.., Molloy P.J. & Beuzenberg E.J, Contributions to a chromosome atlas of the New Zealand flora -
    39. Orchidaceae, NZ J. Bot. 2007, Vol. 45:611-6843