Flora of New Zealand Series

Type sp.: T. longifolia.

Raceme of few to c. 20 fls, sts reduced to one; floral bracts large, us. exceeding ovary. Per. glab., opening widely in sun; dorsal sepal uppermost, similar to lateral sepals and to petals. Labellum similar to petals and sepals, though sts differing slightly in shape. Column short, erect; wings joined in front at base and variously lobed and ornamented at sides and often behind anther; anther ± erect, us. partly or wholly hidden by wings, connective often produced into a short point, pollinia 2 per cell, pollen finely granular; stigma broad, flat, ± bilobed above, us. overlapping base of anther; rostellum small and narrow. Plants terrestrial, glab.; tubers ovoid, new one produced at base of parent plant. Lf solitary, sheathing at base, linear to lanceolate, often thick and fleshy; cauline bracts 1–2, foliaceous. Genus of c. 45 spp., mostly Australian and N.Z., extending also to Philippines and New Caledonia. Perhaps half of the N.Z. spp. endemic, the rest shared with Australia.

• • Fls plain coloured; post-anther lobe present
  • • Cilia lacking:
    • carnea
  • • Cilia white, occ. pinkish; back of column smooth; no distinct side lobules
    • • Fls white or pale pink; cilia tucked under hood:
      • longifolia
    • • Fls between blue and pink; cilia free-standing
      • • Anther quite covered over by smoothly rounded bifid hood:
        • pauciflora
      • • Anther barely covered over; margin of post-anther lobe us. toothed:
        • intermedia
  • • Cilia yellow, sts pale
    • • Back of column tuberculate; side lobules thick and fleshy:
      • formosa
    • • Back of column not tuberculate; no distinct side lobules:
      • hatchii
• • Fls striped; column-arms not terete
  • • Cilia lacking; post-anther lobe absent:
    • venosa,matthewsii
  • • Cilia yellow; post-anther lobe present
    • • Column-arm with conspicuous reddish teeth below sparse cilia:
      • pulchella
    • • Column-arm with inconspicuous whitish teeth below globose mass of cilia:
      • dentata
• • Fls us. spotted; cilia white; back of column tuberculate
  • • Side lobules thick and fleshy; tubercles at back ± finger-like, forming or hiding margin:
    • ixioides
  • • Side lobules not distinct; tubercles at back short, conical, mostly below margin:
    • decora

SYNOPSIS

• A.
• • Column-arms without cilia or fimbriae
  • 1.
  • • Post-anther lobe of column absent; fls striped:
    • 1. venosa, 2. matthewsii
  • 2.
  • • Post-anther lobe of column present, sts short; fls not striped:
    • 3. carnea
• B.
• • Column-arms with either cilia or fimbriae or both
  • 1.
  • • Column-arms ± flattened, us. with fimbriae or teeth or both (mostly coloured), cilia often present also; anthers mostly not entirely hidden by post-anther lobe
    • (a)
    • • Post-anther lobe mostly shorter than anther, often with well-developed calli, flanked by tall side lobules; fls not striped:
      • 4. ixioides, 5. formosa
    • (b)
    • • Post-anther lobe little if at all shorter than anther, without calli or distinct side lobules; fls striped:
      • 6. pulchella, 7. dentata
  • 2.
  • • Column-arms ± terete, cilia present, us. crowded, white or very pale; anther us. overtopped and often quite hidden by post-anther lobe; fls not striped:
    • 8. decora, 9. hatchii, 10. intermedia, 11. longifolia, 12. pauciflora

Colenso described a number of spp. in the years 1884 to 1890 and several of these names are not supported by any known specimens. Most can be placed with varying degrees of confidence in the synonymy of accepted spp. but one remains unresolved; this is T. nervosa Col. in T.N.Z.I. 20, 1888, 207, based on specimens brought by a visitor from "High lands base of Mount Ruapehu".

The column offers the best characters for differentiating between spp., though habitat, lf-form, and shape and colour of per.-segs are also useful. For purposes of description the structures associated with the column and included in the general term "wings" are treated as follows:

Column-arm : This term, adopted from Holttum (Fl. Malaya I, Orchids, 1953, 9) is applied to 2 small processes, one on each side of the anther, and each supplied by a single unbranched vascular bundle; these are thought to represent staminodes. They are of different forms: (a) ribbon-like to ± thickened and clavate, plain or ornamented with teeth or tubercles; (b) each consisting of a ± terete stem bearing on sides, back and top numerous "cilia". i.e. hair-like structures 1–2 cells wide throughout their length; (c) the stem partly to quite flattened, bearing on its lower margins teeth, laciniae or fimbriae which are relatively few, mostly several cells wide at their bases and tapering to their tips, the top of such column-arms sts occupied by more cilia-like structures.

Post-anther lobe : This structure, including what has commonly been called the mid-lobe, lies between the column-arms and mostly behind the anther; it has a ± complex vascular supply, always closely associated with that of the functional anther, and may be thought of as an outgrowth of the filament. In a few spp., e.g. T. venosa, it is represented only by a band of small calli crowded across the back of the anther; in most spp. it stands erect with a free margin and may be short or tall, plain or ornamented with fleshy tubercles, truncate or cucullate, and it is often distinctively coloured. At its maximum development the post-anther lobe forms a somewhat fleshy, well-vasculated hood that overhangs and quite hides the anther.

Side lobule : This is a lobule standing, in a few spp., immediately behind the column-arm and ± distinct from the middle part of the post-anther lobe; it tends to be fleshy with irregularly jagged margins and occ. sharp surface tubercles, but it includes no vascular strand. Species with distinct side lobules have sts been described as having a tripartite mid-lobe.

Some spp. display a wide range of column structure, and many abnormalities are found, such as the column-arm being absent from one side of a column, or from the upper fls of a raceme. Fimbriae are often unevenly developed in the two column-arms of one fl. In the unopened fl. the anther is us. full-grown before the various wing structures attain their full size.

In most spp. fl.-colour ranges from blue to pink with a preponderance of some narrower range, but white fls turn up sporadically in most spp., and the predominantly white-fld T. longifolia includes also pink-fld plants. Not infrequently fls of different colours are found on adjacent plants of one sp. Darker stripes or spots are characteristic of certain spp. Though colour variants are so common and cilia and tubercles may fail to develop, certain relatively easily observed characters are reliable for the majority of plants and the following field guide may be useful.

Fig. 26. THELYMITRA. Flower. Columns from side; also from back (T. formosa, T. intermedia), from above (T. carnea, T. ixioides, T. pauciflora), from front (T. dentata with right-hand column-arm removed, T. longifolia), and bisected longitudinally (T. longifolia). Lettering as in fig. 20, p. 103. © All rights reserved. [Image: 4X2I]