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Journal Number 90
March 2004
EDITORIAL
Colenso's Dark-Purples
By Ian St George
One with affinities to Thelymitra longifolia around Wellington and the southern Wairarapa is a purple-stemmed slender little plant with pink to white flowers in November-December; its column is indistinguishable structurally from T. longifolia, but its shape is otherwise and consistently quite unlike that of T. longifolia.
Close examination of Colenso's description of T. purpureo-fusca (Trans.N.Z.I. 1885; 17: 249), together with the type specimen at Kew, imply this is the taxon he was describing, and the consistency of its structure supports the use of Colenso's name as a useful descriptor.
He wrote,
"The whole plant exceedingly slender, of a dusky purple-brown or purplish-red colour; tubers
narrow, oblong. Leaf narrow, 1½ - 3 lines wide, 7-10 inches long, thickish, channeled, glabrous.
Scape erect, very slender, almost filiform, bibracteate, 8-10 inches long; raceme 3-5-flowered
(occasionally only one); flowers rather distant, bracteolate on long slender pedicels; perianth ½
inch diameter; sepals dark purple-brown edged with a bright green line, a yellow central stripe a
nd broad white exterior margins, sub-ovate-acuminate, much concave, dorsal one largest, the
two laterals with a long mucro; petals light pink, sometimes white, elliptic-oblong, obtuse, broader than sepals; lip the smallest; column pink dashed with blue, apex stout, much emarginate,
incurved, dark and edged with bright yellow (as in T. nemoralis), but the plumose appendages
are more produced and rise above the column; anterior base slightly erose; stigmatic gland
similar to that of T. nemoralis (i.e. bilobed at base, trilobed at apex including rostellum); anther
very acuminate, tip subulate.
Hab. In Fagus woods on dry hills with (T. nemoralis) but usually higher up; 1881-3: W.C.
Obs. I have both sought and watched this plant very closely; from the fact of its widely different general appearance at all stages from T. nemoralis, and yet, on examination and dissection, I find
it possessing such scanty differential characters; the principal ones consisting in its plumose staminodia rising above the tip of the column-its narrower and variegated sepals-its slenderer proportions, dusky aspect and fewer flowers.
In all thses however it is very uniform; as I have seen and examined (through patiently waiting for their development) some scores of flowers and plants. It has also a peculiar habit of growth, being often found in little clumps (like crocuses and jonquils), from which arise 6-12 scapes.
It wears a very striking and elegant appearance, when its dark perianths with their segments edged with white are about expanding, from their contrasts in colour. Notwithstanding the column-appendages being produced beyond its tip, while in T. nemoralis they are below it, this species is naturally very closely allied to that one." |
Thelymitra purpureo-fusca Colenso, Type sheet at Kew Herbarium
Cheeseman regarded both as T. longifolia. No specimen of T. nemoralis has been found,
but the type for T. purpureo-fusca is at Kew (above).
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Drawings of the column
by Mark Clements
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I have examined plants fitting Colenso's description, from clay banks by Airlie Rd at Plimmerton,
and plants Pat Enright showed me in dry gravel by Blue Rock Rd in southern Wairarapa, where they
are smaller.
They are slender, 10cm tall in the dry to 25cm in damp habitat, grow in clumps, have a V-channeled
slender leaf, with stems, bracts, buds and leaves dark purple, and white to pale blue to pink sepals
and petals, the sepal backs purple with a white edge; the column pink, midlobe notched, dark brown,
edged with yellow, the cotton-ball cilia extending above it, the stigma bilobed below and trilobed
above, the pointed anther-cap awl-shaped.
There are differences from Colenso's description: the plant is thicker-stemmed, the pedicels shorter, the cilia hardly taller than the column midlobe, the tip of the anther-cap rather short. Nonetheless there are many similarities, and this is a consistent form in the Thelymitra aff. longifolia aggregate.
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"...sepals ... sub-ovate-acuminate, much concave, dorsal one largest, the two laterals with a long mucro; petals ... elliptic-oblong, obtuse, broader than sepals; lip the smallest" |
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"Leaf narrow, 1½ - 3 lines wide, 7-10 inches long, thickish, channeled, glabrous" |
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". column. anterior base slightly erose; stigmatic gland . bilobed at base, trilobed at apex including rostellum; anther very acuminate, tip subulate" |
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"Fusca" suggests "dark" - "obfuscate" means to darken.
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