Oceania Orchids
Darryl and Alison Smedley

Small Success - Cultivation of some Miniature New Guinea Species

By Darryl Smedley dsmedley@ozemail.com.au

(This article originally appeared in The Orchadian Vol.11 No.8 June 1995).

Success in orchids is relative. Sometimes the goal can be to achieve an outstanding flowering on a large and easily cultivated plant. Othertimes it could just be to ensure survival of some small miserable piece of an otherwise desirable clone. Most times it would be the accomplishment of the aim to grow and flower a plant to its maximum potential under your conditions over a number of seasons. In the case of New Guinea orchids, I would add the desire to discover something about the cultural requirements of the species. This is more so when the species are miniature and have not had the horticultural attention over the years of the large and showy species.

I have grown a few miniature New Guinea species to the point where I could claim some small success. Others I am still experimenting with to find something about their cultural requirements. Habitat information on these species is meagre and hard to find and cultural information is not much better. I hope that the following notes raises the level of cultural knowledge just that little bit.

Cadetia chionantha

I obtained my piece of this species as a small division in 1988. It is a diminutive species, a mature plant is only 5cm high. The pseudobulb and leaf are quite thin. The flowers arise from the axis of the pseudobulb on a pedicel about 15mm long. The 8mm flower is a beautiful crystalline white, triangular in outline with broad lateral sepals for the genus and with a fleshy and prominent labellum. It carries a few flowers for most of the year with the peak display in spring.

The division was potted into a 50mm plastic thumb pot into seedling bark. I surmised that, as the root system was fairly short and thin, a media that was reasonably moisture retentive would suit. The plant had no difficulty in establishing and is still content in its original pot.

The condition of the media is checked each spring to see if it is still serviceable. As it now has a decent root mass it is simple to ease it out, inspect the media and drop it back into the pot. If you intend to keep a plant in the same media for some years it is important that this task is performed routinely to ensure that the media won't go 'off' until next repotting time.

I make sure that the specimen is watered regularly, every 2-3 days at a minimum. It is at the back of the glasshouse in the cooler, more shaded portion where the direct light it receives is minimal. Air movement is not extravagant. The rush from the fan at the front has mostly dissipated by the time the breeze reaches it. The glasshouse is maintained at a minimum of 13^o in winter. The relative humidity is not calculated but it is assessed by that wonderfully subjective technique of smelling the air. A glasshouse humming along with all elements in balance has that evocative tropical forest smell to it. If something is out of whack, usually humidity, especially in winter, it gets a dry raspy smell about it.

This C.chionantha originated from Gerald McCraith in Melbourne who collected it some years ago from a road cutting near Ambua at 3000m in the Southern Highlands of Papua New Guinea. I would guess then, that the species would tolerate temperatures lower than 13^o

This species is mat-forming and quite vigorous. One clone is established on a raft of thick, fibrous tree-fern and the other on a slab of ironbark bark. The first does a little better, no doubt because its substrata holds that little bit more water than the ironbark. I have also seen it grown very successfully in large flat terra-cotta saucers in a seedling type mix. The roots are thin and quite wiry, almost stilt-like. The leaves are succulent and show a slight shrivelling if the water is not kept up to them.

The great thing about this species is that it thrives in cooler temperatures. My plants are in the shadehouse all year and are hung with our cool temperate Bulbophyllums. Growth actually ceases in summer and reactivates in early autumn.

Flowering occurs in late autumn and into winter. They are like little orange and yellow exploding balls, the yellow petals and sepals seeming to burst out from the side of a tiny orange. Each flower is about 6mm in diameter. A well cultivated exhibit will carry dozens of flowers all over the plant, like driblets of colour in a dark green sea.

This species is not as vigorous as the previous species, seeming to grow in loose strands rather than a crowded mat. It does however, share other traits in common. It is cold tolerant, it slows down at the height of summer and comes into flower in late autumn.

The flowers are slightly larger than the previous species. The bulbous part of the flower is scarlet and the petals and sepals are a delicate pink, almost white, like a piece of exploding bubblegum..

I have two clones of this species. One is in an 80mm pot with bark and pebble of about 8mm diameter. The other is in a 100mm Port Pot filled with seedling grade Sequoia bark. The latter grows and flowers a little better. I tried the combination of a large pot filled with small bark to increase the amount of water available to the plant and to increase the humidity in its immediate environment in hot weather. Whether this is a better technique than a large slab of tree-fern I don't know. I'll have to wait 'till I have more material as this species is not all that vigorous.

This species is a little tufted epiphyte from the Section Oxyglossum. It has pale pinkish flowers suffused with purple or blue, arising from almost grass-like pseudobulbs and leaves.

In October 1993 I deflasked seedlings into a tray of 50mm tubes. Half got a mixture of equal parts seedling bark, pebble, milled-up tree-fern fibre and perlite, the other seedling bark and pebble on a 4:1 ratio. Both types produced well grown plants so I won't bother to go to the trouble of concocting a special brew again. However, if you don't try you don't find out.

Most of the seedlings flowered the following autumn. Here's where I made my mistake - I left them outside over the winter. Come spring, some of the plants looked very crook. This disturbed me as I thought they were reasonably high altitude plants and should have been more cold tolerant. Over then to the literature. Reeve & Woods (1989) give the altitude range as 100-1300m. I then asked Phil Spence, from whom I had obtained the flasks, about the source of my D.cyanocentrum. Of course they came from the lower part of the range not far from Port Moresby.

They can come outside for the summer but they will now be overwintered in the glasshouse where they can receive good , but filtered light and that essential winter warmth.

This is a small creeping epiphyte where the small glossy and succulent pseudobulbs and leaves resemble, naturally enough in view of the name, a Bulbophyllum.

I have two clones, a plant originally from Tari Gap in Papua New Guinea courtesy of Fred Fetherston and a seedling from the nursery of Geoff Stocker. When Fred gave me a small division of his piece in 1990, his advice was to mount it on tree-fern and always keep it saturated. It was so mounted and has slowly crept along on its host. Because an effort is made to always keep the mount moist, algae and moss have developed on this totem more than on some others.

The leaves have taken on a paleish hue so I expect that it is suffering from a degree of Nitrogen deficiency induced by the growth of the other material on the host.

It produces its small flowers in the spring and into the summer. The flowers are about 1cm across, orange spotted with maroon with a darker purple labellum. The whole flower is very shiny and lasts about three weeks.

The seedling I obtained in 1989 is still in its original 50mm squat pot. It has grown vigorously and is now 15cm in diameter. The wretched thing has not yet flowered. Both clones aren't too far apart in the glasshouse so there must be some other factor inhibiting flowering in the seedling. Its well known in horticultural circles that cuttings of mature plants can flower much earlier than seedlings. I guess this applies to D.bulbophylloides as well.

Reeve (1983) indicates that the Microphytanthe Section of Dendrobium usually grow on the trunks and large branches of trees in semi-open forest. The altitudinal range of D.bulbophylloides is given as 1000-2750m. In my glasshouse they are in the more shaded end as this is also the coolest. The seedling has grown vigorously in this location so its probable that a position providing only light shade would be optimum to induce flowering.

I hope that these notes assist growers with their cultivation of some of the smaller Australasian species. They are worthwhile subjects and create that added bit of interest in the collection and on the showbench. They can also be champions! The C.chionantha was Champion Other Species at the ANOS Conference at Wollongong in 1993 and one M.decoratum was Reserve Champion of Show at the Orchid Glenn Nursery Show at Dungog in 1993.

Reeve, T.M. (1983). A Revision of Dendrobium Section
Microphytanthe. The Orchadian Vol.7(9): 203-206.

Reeve, T.M & Woods, P.J.B. (1989). A revision of Dendrobium Section Oxyglossum (Orchidaceae). Kew Bulletin Vol46(2): 161-305.

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