Biologue

Issue 26
Australian Biological Resources Study, April 2002
ISSN 0814 B8880

Participatory Programme (continued)

Research Grants (continued)

Articles from ABRS Grantees (continued)

A Taxonomic Revision of the genus Thelymitra J. & G. Forst. (Orchidaceae) in Australia.
Article by Jeffrey A Jeanes, Royal Botanic Gardens Melbourne, Birdwood Avenue Melbourne VIC 3141 Thelymitra is a complex genus consisting of about 75 described species, several described natural hybrids and an uncertain number of undescribed taxa. It is mainly concentrated in higher rainfall areas of temperate Australia, but a few species occur in tropical north-eastern Australia, about 10 endemic species occur in New Zealand and four additional species occur in Indonesia, New Caledonia, New Guinea and the Philippines. J.R. Forster and G. Forster described Thelymitra in 1776, the type species being Thelymitra longifolia from New Zealand. In 1810 Robert Brown prepared the first account of the genus in Australia in which 10 species were described. Bentham (1873) recognised 16 species in 3 sections, Fitzgerald (1875-94) recognised 19 species, Nicholls (1951) recognised 35 species and Jones (1988) recognised 46 species. The most recent work done on the genus has been either taxonomic treatments at a State level in various popular books and in State floras, or as a piecemeal characterisation and description of species in various journal articles. To date, a complete taxonomic revision has never been done of Thelymitra in Australia. The flowers of Thelymitra are unusual for orchids in that the labellum lacks ornamentation and is virtually the same shape, size and colour as the petals and sepals. Traditionally, the column has provided the main suite of characters used to distinguish between the species in Thelymitra. To a large degree this remains true in my research, but vegetative characters such as leaf size, shape, texture and colour and the number, size and colour of the sterile bracts can sometimes help to characterise the species. Other useful features that should be taken into account relate to the colour of the flowers, the colour of the various parts of the column, habitat preference and flowering time. It is evident from the literature, and from my own field and herbarium research, that the genus remains poorly understood and much of the current taxonomy is simplistic and outmoded. In particular several species complexes have never been fully resolved and are in need of further study. The presence of apparent hybrid taxa further complicates the taxonomy of the genus. To date my research has revealed the presence of about 25 new Thelymitra taxa in Australia. I have described five of these in recent journal articles and several more will be described shortly. My ongoing research will undoubtedly reveal the presence of further taxa that are in need of recognition.

A Taxonomic Revision of the genus Thelymitra J. & G. Forst. (Orchidaceae) in Australia.

Article by
Jeffrey A Jeanes, Royal Botanic Gardens Melbourne, Birdwood Avenue Melbourne VIC 3141

Thelymitra is a complex genus consisting of about 75 described species, several described natural hybrids and an uncertain number of undescribed taxa. It is mainly concentrated in higher rainfall areas of temperate Australia, but a few species occur in tropical north-eastern Australia, about 10 endemic species occur in New Zealand and four additional species occur in Indonesia, New Caledonia, New Guinea and the Philippines.

J.R. Forster and G. Forster described Thelymitra in 1776, the type species being Thelymitra longifolia from New Zealand. In 1810 Robert Brown prepared the first account of the genus in Australia in which 10 species were described. Bentham (1873) recognised 16 species in 3 sections, Fitzgerald (1875-94) recognised 19 species, Nicholls (1951) recognised 35 species and Jones (1988) recognised 46 species. The most recent work done on the genus has been either taxonomic treatments at a State level in various popular books and in State floras, or as a piecemeal characterisation and description of species in various journal articles. To date, a complete taxonomic revision has never been done of Thelymitra in Australia.

The flowers of Thelymitra are unusual for orchids in that the labellum lacks ornamentation and is virtually the same shape, size and colour as the petals and sepals. Traditionally, the column has provided the main suite of characters used to distinguish between the species in Thelymitra. To a large degree this remains true in my research, but vegetative characters such as leaf size, shape, texture and colour and the number, size and colour of the sterile bracts can sometimes help to characterise the species. Other useful features that should be taken into account relate to the colour of the flowers, the colour of the various parts of the column, habitat preference and flowering time.

It is evident from the literature, and from my own field and herbarium research, that the genus remains poorly understood and much of the current taxonomy is simplistic and outmoded. In particular several species complexes have never been fully resolved and are in need of further study. The presence of apparent hybrid taxa further complicates the taxonomy of the genus. To date my research has revealed the presence of about 25 new Thelymitra taxa in Australia. I have described five of these in recent journal articles and several more will be described shortly. My ongoing research will undoubtedly reveal the presence of further taxa that are in need of recognition.