The genus name Thelymitra
was coined by J. R. and G. Forster, botanists on Captain Cook's second
voyage in 1772, when naming and describing in 1776 T. longifolia
from the south island of New Zealand.
The name is from
the Greek thelys, a woman and mitra a cap or headpiece and
refers to ladies head coverings of those times.
Burns-Balogh (1989) included Thelymitra, Calochilus and Epiblema
under Thelymitra and states that the staminodes form an elaborately
structured mitra in most species with the rostellum extremely reduced.
This author lists 60 species with major distribution in Australia and
extending into New Zealand and Malaysia.
lists 45 species, 2 varieties and 5 hybrids Australia wide with 22 species,
1 variety and 1 hybrid for South Western Australia. 6 of these being common
to the Eastern States and the remainder endemic.
This paper attempts to cover the Western Australian content and the slide
program that the registrants will have already seen.
RANGE AND DISTRIBUTION
Mother nature has lavishly distributed within a rough triangle from at
least 60 kms north of the Murchison River extending south approximately
750 kms to Augusta thence east to Madura (180 kms from the South Australian
border) approximately 1100 kms and to complete the triangle a span of
approximately 1200 kms. Within this tremendous area most of the Sun Orchids
flourish and are equally at home in the ever changing climate rainfall
and habitat, along the coastline and into the hinterland and extending
well into the arid Goldfields areas where they can survive in shallow
pockets of soil and moss where ground level temperatures can reach 60o
Examples are T. macrophylla, T. antennifera and the presumed (putative)
hybrid T. x macmillanii.
THE COMMON NAME SUN
This reflects the habits of the flowers opening and closing (chasmogamous)
in strong sunlight, however, this process appears to be more complex.
It seems that a combination of warmth, humidity, air movement and pressure
combine to influence opening and closing. As obviously climate and geographic
range will influence different species and a given species, the situation
becomes highly complex therefore it would be speculative to suggest a
precise formula for the variables.
The early flowering orchids in the Albany region seem to have adapted
to suit the climate as they are able to open their flowers at a much lower
temperature than the middle or late flowering species, example T. spiralis
flowers from July-September will open under the most favourable conditions
at temperatures from 17o-20o C and above. T. variegata, T. cornicina
and T. antennifera flowering August - September open at 20-25C
and above. The middle and late flowerers mostly open at around 25-30C.
Cold winds and cloud cover can retard or inhibit flowers opening.
It is common knowledge that flowers can be induced to open in a warm room
where windows and doors are kept closed and the windows are exposed to
direct sunlight. The smaller the room and the more glass, brings a faster
response. An interesting experiment that appears to support the theory
of warmth etc. as against sunlight, is to place the flowers in water in
the confined space of a car boot that is facing the sun's rays, the flowers
will open much quicker than in a room, however, a word of warning, do
not leave the flowers in the boot too long as they will wilt in strong
STRUCTURE AND GROWTH
It is quite futile to dwell on height of stem, length of leaves, numbers
and size of flowers as they all vary in the extreme, seasonal geographic
variation changing habitat within a colony and for a given species, in
other words the measurements etc. are relevant only for the specimen measured.
The flowering stem arises through the leaf sheaf that is attached directly
to the two underground tubers, these can be pear shaped, round or ovoid,
leaf bracts can hug the stem or be free, there is a flower bract below
the ovary on every pedicle (flowering stem). The stem can bear from one
to thirty or more flowers, often all open at once.
Leaves are solitary, often elongated broad to linear lanceolate or oval-oblong,
all are glabrous, except one that is covered in fine downy hair (villose,
T. villosa) and can be lined ridged, fluted and grooved. A member
of the T. macrophylla complex has possibly the largest leaf
that is ridged, fluted and semiplicate and can be extruded under pressure.
The most interesting and unusual leaves are spirally twisted (anticlockwise)
T. spiralis and T. variegata and can be corkscrew like,
five or six turns or a slow spiral of two or three, there is an unusual
process just above ground level that is spatulate and frilled. Initially
leaf growth is straight and starts to curl much later and spirals towards
the end of the growth cycle when the spatulate base also appears, Warren
Stoutamire (pers comm) stated that this leaf is quite unique in the worlds
Orchidaceae and present elsewhere with one species T. matthewsii.
A speculative explanation of this phenomenon could be the result of the
earth's rotation and the geostrophic force created. Climbing plants in
this region twist to the left and snakes coil and water rotates similarly
down the plughole. As to why these two species have variously spiraling
leaves and others do not is a matter for scientific research.
Sun Orchid flowers are "about" a multiplicity of colour and
form, predominantly all shades of blue (most unusual in the worlds orchidaceae)
including purple, magenta, maroon, red, pink, range, yellow and white
or hi-coloured can be lined, striped, peppered, speckled, spotted and
blotched with contrasting colours. Over all there is a lustrous sheen
that has to be seen to be believed, which camera cannot faithfully reproduce.
Flowers are considered
to be regular in shape (radically symmetrical) with the labellum scarcely
different from the rest and completely unadorned by glands or calli, however,
some species, example: T. variegata where some forms have a much
wider dorsal sepal and a much narrower labellum segment. The unique upright
column forms a hood at the apex that can be entire, notched, fringed,
bifed or cleft to varying degrees. The hood encloses and protects the
pollinias, the large oval stigmatic plate covers most of the space below,
the column can be broadly winged and often has erect arms that bear hairy
tufts (Trichome Brushes) that can be dense, sparse, fine, coarse, tangled
and variously coloured white, cream, yellow, blue, purple or maroon, the
overall colour of the column is mostly yellow and can be different to
the segments. The apex and behind the anthers can be variously adorned
with glands, calli and tubercles. With some species there is a conspicuous
crest that is mostly half-moon shaped, with others this is rudimentary
or absent. The species T. cornicina and T. crinita (closely
related) have clusters of densely massed fine hairs capped with gold.
The complexes of T. spiralis and T. variegata have prominent
three lobed appendages of gold or yellow with the centre lobe extending
forward from the apex and the lateral lobes either side. A unique self-pollinating
species T. mucida has a deeply cleft column, the apex and behind
is covered with bloom (mucine) similar to powdered silver frost composed
of thousands of glistening particles, it can be rubbed off and will mark
paper, its function and purpose requires scientific research.
POLLEN AND POLLINATION
It is considered that various species can be derived by type of pollen
and the strategies used to achieve pollination. By far the most successful
are those that self pollinate (autogamous), these species having mealy
pollen that crumbles or powders and falls readily on to the large oval
stigmatic plate examples T. mucida, T. gramiea and T. holmesii.
One group departs from the above, the T. spiralis complex where
pollen is ejected in a semi liquid mass that completely envelopes the
stigma. Within 20-30 minutes, it has shrunk and hardened and now rings
the outer edge with a few wisps extant. Another process is where the pollen
is ejected in two irregular sticky masses that attach themselves to the
upper part of the stigma.
For both of the above, pollen transfers is effected by the under side
of the centre lobe splitting from the apex and folding back in two triangular
Most species are considered to achieve cross pollination by insects, an
assortment of fast flying bees, flies, etc., this will certainly give
an advantage to seed set. These mostly have coherent pollen where pollinias
are removed whole, attached to a viscid disc that glues them to various
parts of the insect's abdomen for transfer. Insects are attracted to perform
this service by fragrance, mimicry, pheromones and the column crests etc.
previously mentioned, however the brilliant colours and variegation is
likely to be the initial attraction: Examples of this section are T.
villosa, T. sargenii, T. variegata, etc., most of these have
a prominent rostellum, that also may play a part with T. variegata
the rostellum is pressed hard against the underside of the centre lobe
that has split exposing the pollinias, any insects would have extreme
difficulty in removing these, this may explain the reason why this species
is seldom observed to be carrying fertilized ovaries.
A small group self pollinates in the bud (cleistogamous) and never opens,
others on the border of this (subcleistogamous) will open their flowers
under favourable conditions, failing that, will self pollinate. Some are
initially able to avoid self pollination by sexual parts maturing at different
times. Examples, forms of the complexes of T.graminea, T. mucida
Unlike the Eastern States there are few records within Thelymitra,
if so this is quite surprising as with non specific pollinators, the reverse
should be expected, natural barriers between species and the vast range
of distribution and few interested people may account for this. From experience
in the Albany Region it has been a most infrequent occurrence, there have
been records of T. macrophylla and T. benthamiana (previously
T. fuscolutea) Herbele 1986. Others have been the crosses T.macrophylla,
T. canaliculata and T. crinita. A major factor that will influence
hybridization will be the number of pollinators and the number of sunny
days that influence flower opening and insect activity. This is supported
by records of hybridization north of Geraldton where T. antennifera,
T. macrophylla, T. campanulata, T. sargentii and T. spiralis
have been observed to hybridize. In these areas there are many more sunny
days and higher temperatures than in the south.
RARE AND ENDANGERED
Two species T. stellata and T. psammophila are declared
under the Wildlife Conservation Act 1950. Both these species status have
been proved to be highly controversial as is a species loosely identified
as T. benthamiana listed in the Conservation and Land Management
Department's publication, Western Australia's Endangered Flora (1990).
T. stellata appears to be a member of the widespread T fuscolutea
complex as does T benthamiana, both could be simply different colour
forms of T. fuscolutea. Clements (1989) states that T. benthamiana
is the common wide-spread species that has been called T. fuscolutea.
is considered by some to be a natural hybrid between T. flexuosa
and T. antennifera, from most locations both of these species are
As previously outlined
in sections covering range and distribution it would seem that most species
are adequately conserved, from my contact with enthusiasts over this range,
it is apparent that the knowledge is with those who live close to where
orchids grow, there is a need for this knowledge to be pooled and for
the professional sector to take advantage, without this the full story
will never be known.
It's incidence and frequency has an impact on the flowering cycle, whilst
I know of no species that is entirely dependent on fire to flower, fire
can influence a greater abundance in a given season. Some swamp growing
species will not flower without it, whereas in other locations they are
independent, examples, T. tigrina, T. cucullata and T. canaliculata,
the timing of the fire is critical.
Early flowering species will respond to a previous December-January fire,
middle flowerers late January, February to early March, late flowerers
It is debatable just
how the fire influences this flowering phenomena. It seems most unlikely
that gasses released from the combustion of vegetative material would
penetrate the soil to the depths of the tubers, 15 cm or more below the
surface (gas rises). The residue ash after rain could provide nutrients
or heated soil could reactivate dormant mycorrhizal fungal associates,
there could be other unknown factors, here again scientific research is
It follows that Conservation and Land Management's policy of controlled
fuel reduction burning in the autumn or at late spring will effectively
prevent most orchids flowering in that and the subsequent year. Most orchids
have their leaves above ground or close to the surface in the autumn,
fire destroys these and prevents flowering.
Late spring fires destroy all flowering plants, prevent seed set and ensure
that most do not flower the following year. This could be a reason why
orchids are declared rare and endangered.
CALOCHILUS AND EPIBLEMA
and Bernhardt (1989) have included these two with Thelymitra, it
is necessary to cover them.
There are four calochilus recorded for Western Australia, C.
robertsonii is widely distributed and shows the typical bearded segment.
C. compesteris was found by a member of the Albany Branch of the Wildflower
Society, Mrs. Barbara Hall in early November 1983 flowering in the sand
plains of the South Stirlings east of Albany. It has since been found
in the Hopetown area and last year was recorded in the Fitzgerald National
Park nearby, flowering on a previous summer burn. These species appear
to be capable of being pollinated by insects but eventually self pollinate.
Two species are found in the Kimberlies in the far north. C. caeruleus
and C. holtzei.
Epiblema is a monotypic genus, the species E. grandiflora is
one of our most unique and attractive species. The distribution is from
the Metropolitan areas of Perth along the coastal plain to the east of
Esperance where it flowers January-February in winter wet swamps, sometimes
in water. Over this range it maintains its integrity varying only in colour
from deep purple to violet. Erickson (1951) gives an interesting coverage
and tells a delightful story of how children influenced the common name
It would appear that the genus in the South Western Australia reflects
many unique features. The super abundance of most species (in the right
year) and the tremendous range of most of species reflects a high degree
of development and specialization that has been extremely successful in
perpetuating the species, suggesting that contrary to the findings of
Van Der Pijil and Dobson (1966) the genus is far from primitive.
This paper is written to clarify some of the complexities of the genus
and does not attempt to cover all of the species and is complimentary
to the slide program presented at the Conference.
These two sections
are a combination of my personal activities and observations assisted
by Don Voigt, Mary Sherwood, Viv Holly, Patricia Dundas, Eric and Patricia
O'Halloran, Wayne Merritt, Tibor Bodrogai and the late Herb Foote, to
whom I owe my grateful thanks, also to my wife Pauline for her tolerance
and field work over the years.