THUNIA ALBA, (Lindi.) Rchb. f. Syn. T marshalliana Rchb.f.

Walter T. Upton

I obtained my original plant from Harold Wombey of Manly Orchid Society on 17th January 1960. One old leafless stem and one new growth 9 inches high in a 4 inch pot. The plant I have just drawn was given to me by Bill Dobson. Both of these plants were under the name of T. marshallialla, certainly the most popular name for this plant. I do not think it is necessary to change the label at the present time, as there are still lots of different opinions on this genus.

Although we have always grown this in Australia as T. marshalliana (1877), it seems the general opinion among today's botanists that the earlier name T. alba (1852) is the accepted one. However, looking through numerous descriptions of them both, one finds there are differences, but these are very slight and not enough to make two separate taxa. Such things as the size of the labellum, it is shorter in T. marshalhana, and the length of the hairs on it are longer and more numerous. The difference in the colour of the keels and the veins on the labellum is often quoted but all the colour descriptions are not constant on this point, it makes one realise it is a very variable species, particularly as far as the labellum is concerned. The shape of the flowering bracts and the length of the raceme are also mentioned as differences. I have seen both species and find it difficult to distinguish between them. One has to ask are there two different taxa?

This species has a wide distribution from India and Sri Lanka through Burma to China, Thailand and Malaysia. It is found in the lower mountain areas at approximately 600 - 1000 m, in shady damp forests growing as a terrestrial or semi-epiphyte.

The name Thunia is after Count von Thun Hohenstein of Tetschin, in Bohemia.

Thunia has no pseudobulbs, the jointed fleshy stems or canes, 30 - 90 cm long, have leafy sheaths at the base and as they progress up become true leaves about 20 cm long. The sepals and petals of the large flowers, on a pendulous raceme, are pure white. The labellum on the plant drawn is pure white on the basal half, except the five keels or crests, which are an orange colour and the large area on the apical half of the lamina of the labellum, is from orange at its base to yellow at the front. The veins are orange with a slight brown/purple tinge to them. The larger hairs on the keels and veins are from 5 - 71mn long. The densely fringed edge of the coloured area is white.

When drawing an orchid one learns so much, and sees what a casual glance does not, particularly through the microscope. Notice in drawing (B), the unusual shape of the anther and the very large three lobed rostellurn (F), shows two horns at the base of the flower's pedicel (cut away), 1 have never noticed this before. (1), shows the small 'horn' at the tip of one of the lateral sepals, this was on all lateral sepals on the raceme drawn.

Thunia species are very hardy. I grew it outside in pots in an area with plenty of air movement, in light broken sunlight, away from direct sunlight. It is potted in a mixture of leaf mould, fibrous loam, sand, bark and well rotted cow, sheep or poultry manure, with lots of broken crocks in the bottom to ensure perfect drainage, which is very essential. My records show my very original mix was equal parts of fern fibre sifting's, granular charcoal, rich bush leaf mould, light sandy loam and old powdered cow manure. The recommended minimum winter temperature is 4 - 10' C. After flowering in January/February and as soon as the foliage starts to yellow (Autumn) remove to a cool dry area, in full sunlight to dry stems. The rest period will last through winter, (from leaves dropping off till spring). Place old stems on sphagnum moss to promote new growth. Annual repotting is most beneficial to these orchids. Repot as soon as new growth appear in the spring, very little water until new roots enter medium, then regular watering. New shoots are very susceptible to damping off, do not allow water to remain in new shoots, it is safer to dip pot until new growths are at least 75mm high (3 inches). When new growths are about 20 cm high (8 inches), weak liquid cow manure at least twice a week helps. It is essential to bring the growth to maturity quickly, so copious waterings and feeding is necessary, some place about 50mm (2 inches) of old cow manure on top of the medium. A short fat stem will flower. Badly grown plants will produce long slender stems, and seldom flower. This can be caused by too much water and warmth at the wrong time, and not being given a long dry winter rest. When growth is complete and before flower buds appear, cease overhead watering but keep medium moist by regular dipping. When actively growing ensure plants are in a bright sunny spot.

Plants can be easily propagated by cutting the previous years stems into lengths of approximately 15 cm. Then inserting them firmly into pots in the spring.

Thunia alba (Lindl) Rchb. F

A: Flower, front view 1/2X;
B: Top of column, front view 2X;
C: Flower, side view 2/3 X,
D: Column and labellum, side view IX;
E: Labellum flattened IX;
F: Two horns at the base of flower pedicel 2X,-
G.. Pollinarium, 6X;
H: Anther 4Xl.
I: Tip of lateral sepal 2X,-
J: Plant 1/8 X.
a - anther, k - keels, p - pollinia, r - rostellum, s - stigma.

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Elanbee Orchids