Dendrobium – NOSSA

Orchids in Medicine?

Question: Are orchids used in medicine?

Answer: Worldwide, some orchids are used medicinally but compared with other families, despite their numerical dominance in the plant world, orchids only contribute a small number of species to medicine.

Orchidaceae is the second** largest Family in the world after Asteraceae which has about 32,280* species whilst the orchids consists of about 27,753 species. In the big picture, their numbers are similar but only 2.32% (619) of all orchids species can be considered medicinal as opposed to 7.17% (2,314) of Asteraceae.

It is worth noting, that only 28,187 (6.48%) of the possible 434,910 species worldwide are recorded as being used medicinally. But of all of the world’s families it is the small Family of Moraceae (Mulberry, Figs & Mallow) that contributes the most. Of its 1,229 species 22.54% are medicinally useful.

	Total number species	Percent of species used medicinally	Number of Species used medicinally
World wide	434,910	6.48%	28,187

Asteraceae	32,280	7.17%	2,314
Orchidaceae	27,753	2.23%	619
Moraceae	1,229	22.54%	277

Concerning Australian orchids only a handful are known to have been used medicinally such as Cymbidium for dysentery, Dendrobium teretifolium bruised leaves for pain relief and different parts of Dendrobium discolor as a poultice and for ringworm.

Cym caniculatum drawing

Notes:

**Many sources will state that the Orchid Family is the largest Family worldwide but for the purpose of this article, the information used is from 2017 State of the World’s Plants. Species numbers tend to be a in state of flux as botanists are discovering new and reassessing data.

*All figures in this article are based upon figures found in the 2017 State of the World’s Plants report.

Reference:

https://stateoftheworldsplants.com/ accessed 9 June 2017

https://academic.oup.com/qjmed/article/98/9/625/1547881/The-uses-and-misuses-of-orchids-in-medicine accessed 9 June 2017

Gleanings From the Journal: Rescuing apparently ‘dead’ orchids Parts 2 & 3 of Three Parts

This week we continue with both Part Two and Part Three of Brendan Killen’s Rescuing Apparently ‘Dead’ Orchids which appeared in the Volume 31 No 9 October 2007 and Volume 31 Bi 11 December 2007, respectively.

Rescuing apparently ‘dead’ orchids. Part 2 By Brendan Killen

PLANT #2 – Dendrobium Alick Dockrill “Pale Face”

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The cane pieces of this plant were inserted into a bark mix at the same time as the canes of Den. Jayden ‘JANE’ [See the July Journal] were inserted into sphagnum moss. The outcome is three healthy growths.

Note the dried ends of the canes where they were cut into separate pieces. As you can see from the photograph, I used a green twisty to hold the canes in the bark as a fairly solid bunch – I find this is the best way to keep the canes still whilst they are developing sensitive new growths. I have found that no matter how bunched-up the canes are, the new growths always find a way to the surface.

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Here is a different angle on the new growths with my fingers providing some perspective on the size of the growths.

Note that they are significantly larger that those on the Den Jayden ‘JANE’, with the same time in the pots.

I do not consider this evidence of the worth of bark compared to sphagnum moss.

I find that different hybrids and species behave quite differently in terms of their speed and timing of production of new growths. I believe that it is a function of what species are in the background of these plants and the time of year the rescue is undertaken.

Here is the same plant 5 weeks later. The new roots are protruding from the pot and the new growths are extending themselves – all of this at a time where severe water restrictions limit me to two waterings each week by watering can!

Plant 2-3 Den Alick dockrill 'Pale Face'.jpg

Plant 2-4 Den Alick dockrill 'Pale Face'.jpg

A further 4 weeks of cultivation and bright, warm weather has fully extended and hardened the new growths.

The larger growth should produce a flower spike this Spring.

Dendrobium Alick Docrill “Pale Face” (Photographer: Josh Bridge)

TO BE CONTINUED

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Rescuing apparently ‘dead’ orchids. Part 3

By Brendan Killen

Plant #3 – Dendrobium Sarah Jane ‘Purvis’

This is a plant that the late John Purvis gave me just before he passed away. Because it is a special plant to me, I cut an old cane into three pieces to produce a back-up plant, just in case my piece of the original fell foul of the orchid gremlins.

Journal

As you can see, it is the least developed of the three plants featured in this article. And yet, the parent plant has produced two magnificent new growths in the same period. I feel that the 12.5% of Den. bigibbum and 12.5% of the hot growing Den. tetragonum var. giganteum have influenced this. This new growth has probably been encouraged since the relocation from Adelaide to Brisbane where the temperature differences overnight are more subtle than in the Adelaide Hills where the plants were previously cultivated. The two hot growing species in the plant’s background were probably held back by Adelaide’s much cooler overnight temperatures. Anyway, this is purely conjecture on my behalf. What is important is that I now have a developing back-up plant for one that I treasure dearly.

Dendrobium Sarah Jane ‘Purvis’ (Photographer Josh Bridge)

SUMMARY

The thrust of what I have written is simple – don’t give up on treasured plants that look like they have expired, because there is always hope so long as the canes haven’t turned into fermented mush! The technique is as simple as cutting canes into lengths where you have at least three, preferably four, segments from which new growths will materialise. Use sterilized cutting tools to avoid contamination of the canes. Once the new growths have emerged, give them time to produce healthy root systems and let the new canes harden before potting-on. The best time I have found to pot-on the new growths is early autumn.

****************

Thank you to Josh Bridge for supplying images of the flowers of Dendrobium Alick Dockrill “Pale Face” and Dendrobium Sarah Jane ‘Purvis’ as they were not in the original articles.

***************

Another technique demonstrated by John Gay at one of the NOSSA meetings a couple of years ago was to take the apparently dead canes of an epiphytic orchid and seal them in a plastic bag with a small piece of damp sponge (or other cloth) and leave them in the shadehouse. Do not let the sponge dry out. So long as there was a bit of moisture, there was a chance for new growth on the shrivelled canes. Once the growth was obvious, pot on as normal.

GLEANINGS FROM THE JOURNALS: Part 1 of 3 parts Rescuing apparently ‘dead’ orchids

The following is part of a three part series on reviving apparently dead epiphytic orchids from Volume 31 No6 July 2007

Rescuing Apparently ‘dead’ Orchids

By Brendan Killen

In late Spring 2006, I had an ‘open shade house’ event at my place in Belair, South Australia. As part of the programme, I demonstrated how I rescue orchids that have all but died. My demonstration was based on many years of experience in not giving in to the demons that cause orchids to expire.

I used two orchids that everyone attending agreed would normally be tossed into the rubbish bin or compost – all bare canes; heavily shrivelled; all new growth ‘eyes’ at the base of the canes chewed out by insects. In other words, an apparently hopeless situation. I’ve never given up on these terminal plants, believing that they still had life in the old canes along as they hadn’t turned to fermented mush.

I also used an apparently ‘dead’ cane from a treasured orchid that I was hoping would eventually produce a back-up plant using the method I describe in the following text.

In one case (Dendrobium Jayden), I cut the canes into a number of segments and stuck them into a pot with heavily compressed sphagnum moss, topped with river gravel to suppress the moss from growing and overtaking the pot. In the other two cases (Den. Alick Dockrill & Den. Sarah Jane), I cut the canes into segments and placed them in a pot of small composted bark.

The following photographs were taken about 3 months after the repotting demonstration and after the plants were relocated to Brisbane. They demonstrate the benefit of the right technique and a ‘don’t give up’ attitude. This technique has not failed me yet, allowing me to rescue many prized plants that have gone on to be show-bench winners.

PLANT #1 – Dendrobium Jayden “Jane”.

This photo illustrates the emerging new growth on a Den. Jayden “Jane”. This is the first evidence that success is at hand. It is also the first new growth discovered on this plant before I inspect the canes further to see if there are any other new growths buried within the sphagnum moss.

Plant 1-2 Den Jayden 'Jane'.jpg

In this photo, you can see that the new growth is very pale from having emerged from deep in the sphagnum moss with little exposure to light. The juvenile roots can be seen emerging on the right hand side.

Plant 1-2-2 Den Jayden 'Jane'.jpg

A closer inspection reveals another growth, on the other side. Note that both growths are not coming from the ‘eyes’ at the bottom of the canes – simply because they were cut off at potting time. They are emerging from the section that joins the cane segments.

Plant 1-3 Den Jayden 'Jane'.jpg

Teasing away the sphagnum moss reveals even more of the young roots. Note how the new growths are lacking any colour substance at this stage.

If I were to ignore this plant for much longer, the new growths would have rotted in the very moist sphagnum moss, neutralising my efforts. So, the lesson here is to ensure that you monitor the plants for new growths and ensure that you elevate the new growths above the sphagnum moss to give them a chance to ‘harden off’ from their immersion deeper in the sphagnum.

Plant 1-4 Den Jayden 'Jane'.jpg

This photo illustrates how I have re-seated the canes within the sphagnum moss, but much higher so that only the roots are exposed to the heavy moisture content of the moss. I choose to do this instead of placing them straight into a bark mix as I find that the plants tend to go into a shock at the relative lack of moisture in bark and can die quickly, or suffer from stunted growth. I wait until the new growths have matured with substantial green substance before I repot them in a bark mix. And, I tend to do this in late autumn when they are not under any temperature or light stress. By spring, they will be racing ahead in the bark mix with new root growth and, possibly new canes and/or flower spikes.

One Month Later……….

Plant 1-5 Den Jayden 'Jane'.jpg

After one month from the re-seating described previously, note that the pale new growth is now mature and bright green. And, note how the roots are emerging from the growth above the sphagnum moss. This plant will be ready for potting-on into a bark medium in the next few weeks as autumn cools the air in Brisbane.

Plant 1-6 Den Jayden 'Jane'.jpg — Den Jayden ‘JANE’ in flower

This is how I expect it to flower in spring

TO BE CONTINUED …..

Gleanings from the Journals: Dockrillia linguiformis 2006

This week’s blog is an extract from Volume 30 No 10 November 2006. In this article of Len Field he gives not only cultural notes but also some interesting background including an orchid link with the infamous Captain Bligh.

Dockrillia linguiformis (Sw) 1800 Brieger

Len Field
Common names Thumbnail orchid, Tongue orchid, and in North Queensland the Tick
orchid.
The name linguiforme is from the Latin lingu(a) as in linguiforme (a tongue). It was also claimed for many years that this was the orchid that Olaf Peter Swartz the German botanist founded the genus Dendrobium in 1800, but this was wrong, although this was the first orchid seen by white man when they landed at the rocks area in Sydney cove, Port Jackson. It was introduced into England by Rear Admiral Bligh of Bounty fame.
Other names it has been called are
Dendrobium linguiforme var. linguiforme Swartze 1800
Callista linguiforme (Swartze) Rev. Kuntze 1891
Dendrobium linguiforme (Swartze) var. huntianum Rupp 1942
There was another variety named from this species called var. huntianum by Rupp in 1942, which was named after T.E. Hunt and is a June or July flower and found near Ipswitch (sic) in Queensland, but as it reverts to type form it never reached true variety status and was considered just a variation of the type form.
This orchid has a huge range of habitat which stretches from almost the Victorian border up to North Queensland and West to the Great Dividing Range. It is very common throughout this area and equally happy as an epiphyte or a lithophyte but where as a epiphyte it likes swamp oaks (Casuarina glauca), river oaks (Casuarina cunninghamiana), in fact it will grow on most trees that will hold there bark including the tea trees (Leptospermum species). I have seen this orchid hundreds of kilometres inland from the coast still forming large mats on the rock faces, while in its more prolific growing areas these mats will cover huge areas of the rocks where it can survive and grow in extreme exposed conditions that would kill other orchids. In the dry times the leaves which are very thick, tough and numerous will shrivel and can last up to six months without water. This is a feature of a lot of Australian Dendrobium and Dockrillia
Flowering is from August to October with blooms that are long lasting, up to two weeks with one raceme per leaf.
Culture. If grown on slabs which is the usual way it should be hung up high and if grown in pots a very coarse open mix. In nature it likes plenty of sunlight although at times it will grow in shade. Whichever way it is grown it should have good light, humidity and air movement.

Den linguiforme drawing — Dendrobium linguiforme

Gleanings From the Journal #3 – Native Orchids The Epiphytes: August

The following article is from Vol. 32 No 7 August 2008 Journal of the Native Orchid Society of South Australia Inc.

Native Orchids. The Epiphytes: August.
Steve Howard

Movement of our natives towards flowering is often rapid. How often do we look at our plants thinking that they will never be out in time then take a look the week after and they have doubled in size. Dendrobium speciosum is a classic example of this. One minute the plant is covered in acorn like flower buds then a week later there are bunches of flowering buds everywhere. There is the temptation to force them on but I would leave that until the last two weeks prior to show before making that call. Then we have the Sarcochilus. These can stay in bud for months and not do a thing then suddenly they are away.

On the epiphyte side we should have a heap of buds everywhere on the flowering plants. They key is to keep these under cover and away from rain and also slugs and snails that have a nasty habit of chomping into them. Rain exaggerates fungal problems that will rot out a flower spike overnight. Also avoid temperature extremes, especially once the buds start showing on a lengthening spike. Bud drop occurs quickly and the loss of even one bud will sway the judge’s decision. Even and strong light now becomes important especially for those epiphytes with Den. speciosum and Den. kingianum in the background. The reason is we need to create strong upright racemes to support the flowers. No point having the spikes hanging over the side of the plant and then have the flowers doing the same. Some species do have this trait and as such do not make very good parents if this trait is passed on in hybridisation. I like my flowers to look at me and cannot see the point in lying on the ground and looking up at the plants on the bench. Strong light will assist this spike development as does the potassium and potash in the fertiliser. This is also a reason we tend to avoid high nitrogen feeds in our feeding programme. Even light is also important in order that the flowers will be evenly distributed around the pot as opposed to all facing the one way. Hanging flowering plants is one way we can get this even light.

Now is also a good time to clean up our plants before flowering. Remove husks over the canes, remove dead leafless canes and trim and clean the leaves. It is easier to do this now whilst the spikes are on the small side. Also give the pots a scrub too. All of these tips will help make things a little easier when it comes time to prepare the plants before show. Also make sure you have some fresh topping for the pots. It’s these little things that helps improve the presentation of our plants.

Only remove leafless canes if you think they have completed their flowering potential as many will flower for years after losing leaves or if the cane affects the appearance of the plant. If the forward growths are struggling under no circumstance remove the leafless cane unless it is absolutely dead as the struggling plant would be relying on stored nutrients in this cane to survive. I would then concentrate on why is the plant in the state in the first place.

Even though we are two months away from re potting and dividing our plants it is now time to take stock of what plants will be potted on, divided or sold off on the trading table. That way we can arrange pots, mix etc in preparation. The other thing I am looking at now is where am I going to move my plants this year. Last years heat exposed many plants that are susceptible to heat and with the probability that this will happen more frequently in the future there is the need to move these prone plants from where they are at present. Leave them where they are and the same thing will happen again. There will also be the need that these tender plants be removed from the collection and the emphasis placed on more hardy species and hybrids.

Watering will be dependent on the hybrids you grow and where the parents originate from. Most of the hot/cold type have the tropical hard cane types in the breeding eg Den. bigibbum and these require dry winters so we need to take this into account here. I do not dry them out completely but then again don’t water them frequently either. I aim for slightly moist at all times to keep the roots in good condition. The others with Den. speciosum, kingianum, falcorostrum all come from cooler climates that receive winter rains and as such can handle being damp over winter. Avoid over wetness as this will be to the detriment of the plants. These plants require a short dry period after flowering to mimic the same dry spring period experienced in the areas where most of them come from. I find that with our reduced rainfall of late, nature provides my plants with enough water apart from the mounted plants that get the odd mist or squirt. Any watering should be confined to the warmer part of the day after lunch. Early morning squirts with water from a hose that has been sitting on a frozen ground all night will not do your plants any favours. Feeding during these cooler months is infrequent and if you miss them for a month or more will not cause too many issues. Plants under cover get watered every couple of weeks and these are usually the hot colds.

You will have a few late season new growths reaching full size. Keep an eye on these as they are very prone to rot when water sits in the axils of the new growths. If you notice a growth go reddish or yellow it is a good bet that it has rotted. You can cut the growth off below the infection and treat with a fungicide. I then dry the plant out as a precaution and take a mental note. This plant will always be prone to attack.

My plant of the month is Den. aemulum, the feather orchid. This compact growing epiphyte comes from central NSW (New South Wales) to Qld (Queensland) and comes in 2 forms. The iron bark form strangely enough grows on the iron bark tree, a heavily permanent barked member of the eucalyptus family. It has small cylindrical psuedobulbs that grow in a radial pattern topped with two small and rather thick leaves. Small white clusters of flowers that go pink as they age are borne apically over several seasons from the one cane. The other form commonly seen is the brush box form. This is the long caned variety and the two are found in similar areas. These are not often seen in collections and have the habit of slowly fading away in cultivation unless their requirements of light, a suitable host and conditions are met. I have several plants on different hosts and the results are mixed. The best plant grows east on a slab of hardwood in a rather protected spot and is the brush box form. The iron bark forms appear to struggle on mounts of Callistemon and paperbark. Maybe it is the acidic gummy excretions from the bark of the ironbark that are missing. These plants have not been used in hybridisation very much as they do not have the traits that hybridists are looking for. Nevertheless I find them a very attractive flower when grown into a specimen plant and they will always have a place in my collection. They are not easy to obtain and generally restricted to those that have permits to collect them from the wild.

Next month is September and with it the warming weather and a profusion of flowers. We will look at a few tips to help with the presentation of show flowers but also look back at those that did not flower well or flower at all and see where we can improve and what went wrong.

Epiphytes in flower (1) — Annual NOSSA Spring Show

SHOWY SPECIOSUM

A very popular orchid grown in culture in South Australia is the epiphytic/lithophytic Dendrobium speciosum. It is a showy species with a heady perfume.

This species ranges along the eastern seaboard from Queensland just peeking into Victoria. There are nine variations each with its own unique distribution.

But not only is it popular in South Australia, it is popular throughout the country. The whole of the 2006 September issue of the Orchadian was devoted to a single article on D. speciosum. The March 2016 Orchadian has three articles plus references to D. speciosum in other articles.

And then there is Gerry Walsh who is so passionate about this species that he has a comprehensive website – The Rock Lily Man – devoted to it. Explore and enjoy his website.

Calliope Range, Sept 2005 — Photo source The Rock Lily Man

The Orchid Club of South Australia has produced a fact sheet for growing this species in South Australia.

Growing Dendrobium aemulum in Adelaide 1983 and Now

In 1983, Ron Robjohns, NOSSA’s first treasurer, wrote a comprehensive series of articles about growing epiphytes in South Australia. Thirty years on Ron’s information for growing is still helpful and applicable for today. Any updates or extra information are in black text.

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL

Volume 7, No. 9, October, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Dendrobium aemulum (Iron Bark Orchid)

There are several growth forms of this orchid due probably to the wide variety of habitats, the flowers of all forms being similar. It has a range from the Clyde River in south eastern New South Wales to the Atherton Tablelands in Queensland

Those growing in the rainforests of New South Wales and Queensland have straight stems up to 20 cm long with 2-4 shining dark green leaves. On the edge of the rainforests in northern New South Wales and southern Queensland in the dense brush forest, the principal hosts are the trunks of “Brush Box” trees where it has stems up to 30 cm long which tend to radiate from a central point. It also has 2-4 dark green leaves. In the open forest areas its hosts are the “Iron Bark” eucalyptus trees, it has shorter (up to 7 cm), stouter (up to) 1 cm), and more crowded stems, sometimes growing into large mats and having 2-4 yellowish green leaves. On the Atherton Tablelands at an altitude of around 750 metres and with callitris trees as its favoured host, it has very slender stems of about 0.3 cm with usually only two dark green leaves.

The flowering period is August/September. One to three slender racemes (5-10 cm long) occur terminally from between the leaves or at nodes along the stem, each raceme bearing 3-20 cm diameter. The flowers are usually pure white (sometimes pale cream) with purple markings on the labellum, the whole raceme turning deep pink before withering.

This is another of our natives which to date does not appear to have attracted much attention from the hybridisers. “Emmy” aemulum x kingianum seems to be the only registered cross.

I find D. aemulum is an easily cultivated and highly rewarding plant that flowers freely with masses of feathery flowers. It grows well mounted on hardwood slabs, cork or on a paperbark branch under 50% shadecloth. Mine get about 65% shade in mid-summer and receive an occasional spray of weak foliar fertiliser during the growing period.

Reference: Dockerill “Australian Indigenous Orchids”.

Growing Dendrobium gracilicaule in Adelaide 1983 and Now

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL
Volume 7, No. 8, September, 1983
GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns
Dendrobium gracilicaule
D. gracilicaule is found from Kiama in eastern New South Wales to the Bloomfield River in the south east of Cape York Peninsula in Queensland. It has one of the widest ranges of habitat of any of our epiphytic orchids, growing in the light coastal scrubs, the dense rainforests and, in the tropical areas, on the tablelands. With such a variation in altitude (from near sea-level to about 1200 metres) it follows that there is a wide variety of hosts, even occasionally growing as a lithophyte on rocks.
The stems are long, thin and cylindrical, ½ to 1 cm thick, and from 20 to 60 cm in length with 3 to 6 ovate to lanceolate, terminal leaves, 5 to 13 cm long and of rather thin, leathery texture.
The racemes are short (5 to 12 cm) and bear 5 to 14 small, cup-shaped flowers of a dull or light yellow colour having the outer sepals lightly to heavily blotched or spotted with a brown or red-brown. Occasionally they are found a brighter yellow and without blotching. The flowering season is from July to September.
D. gracilicaule must surely be one of the hardiest and easily cultivated of our Australian epiphytic orchid species as it is adaptable to almost any conditions. I have it growing and flowering on hardwood slabs, paperbark limbs and in a pot, but I think it is better if mounted. It receives 50% – 60% shade and occasional foliar fertiliser. I protect it from frost but the cold does not affect it.
It does not flower from first year stems but will flower from mature stems for several years, even after they are leafless. Although most racemes are terminal or near, I have had racemes occurring from nodes halfway along a leafless canes.
There are two natural hybrids, i.e. D. x suffusum and D. x gracillimum. D. x gracillimum is a natural hybrid between D. gracilicaule and D. speciosum in which the features of D. gracilicaule are dominant in the flower while in D. x suffusum, the natural hybrid between D. gracilicaule and D. kingianum, D. kingianum is the dominant parent. D. gracilicaule has not attracted professional hybridists, probably because the flowers are not as outstanding as many of our other epiphytes, only two crosses appear to be registered: D. Susan (D. gracilicaule x D. falcorostrum) and D. Shan Leaney (D. gracilicaule x D. gracillimum).

Growing Dendrobium pugioniforme in Adelaide 1983 and Now

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL

Volume 7, No. 7, August, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Dendrobium pugioniforme (Dagger Orchid)

This is an epiphyte frequently growing into large pendulous masses on the branches or trunks of trees, mainly in the rain forest areas from Mt. Dromedary on the south coast of New South Wales northwards to the Bunyah Mountains in south eastern Queensland. The stems are slender, wiry and branching, often quite long and usually tangled. Thin creeping roots develop freely from nodes at the branches.

The distinguishing feature of the numerous shiny, thick flat, ovate to lanceolate leaves is the sharply pointed tip.

The flowers are usually single but sometimes 2 or 3 per inflorescence and are 2 to 2½ cm in diameter. The petals and sepals are light green, the labellum pale with bright red or purple markings. The flowering season is September to November.

It is a reasonably hardy plant which will respond to cultivation on quite a variety of hosts. I have had success using Melaleuca, and find that it responds to a position having plenty of shade and moisture, particularly during our summer. Although in the wild it will tolerate cold conditions, (being found from near sea level to around 1300 metres), it will require shelter from our winter frosts

Most authorities designate it an epiphyte, however, in “The Orchadian” Vol. 4, No. 2, p. 24 (1972) D.L. Jones reports having found a bleached and tough looking plant growing on Alum Mountain with its roots amongst leaf litter in a crevice. Again in “The Orchadian” Vol. 7, No. 7, p. 164 (1983) G. Walsh describes ‘inter alia‘ lithophytic forms of D. pugioniforme growing in the Illawarra District of New South Wales.

In view of this it could possibly be grown in a pot, but as it grows quite readily on a slab I have felt it pointless to possibly waste a plant just to grow it in a pot. Fertilise in the growing season with foliar fertiliser at half the recommended strength.

Two naturally occurring hybrids of D. pugioniforme have been recorded – D. pugioniforme x D. tenuissimum and D. pugioniforme x D. beckleri but they are relatively rare (Ford, “The Orchadian”, Vol, 3, No. 7, p.88: Dockerill, Aust. Indig. Orch. Vol. 1, pp 370-371) and as yet it has not yet attracted the hybridists as there does not appear to be any registered crossings.

Growing Dendrobium tetragonum in Adelaide 1983 and Now

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL

Volume 7, No. 6, July, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Dendrobium tetragonum (Tree Spider Orchid)

A variable epiphytic species growing mainly in rainforest areas from Illawarra in New South Wales to the Endeavour River in Queensland. A favourite haunt is on trees overhanging water, often in deep shade. It has a variety of hosts (including Myrtles, Eugenias, Water Gums and occasionally Melaleuca) on which it grows into small clumps. Altitude is of little concern as it is found from near sea level to approximately 1000 metres.

The stems, which are semi-pendulous and from 6 to 45 cm long, arise from a prostrate and branching rhizome They are round, thin and wiry at the base but thickening to become rectangular (hence the name tetragonum – derived from the Greek “tetra” meaning “four-sided”), then tapering slightly before the leaves. There are from 2 to 5 leaves up to 8 cm long at the end of the stems. They are deep green in colour and often with crinkled or wavy margins.

The racemes appear from between the leaves but are short and have from 1 to 5 flowers which are widely spreading and spidery in appearance. The colour is greenish/yellow with irregular and variable brown, red and purple markings. In size the flowers are from 4 to 9 cm from the top of the dorsal sepal to the tip of the lateral sepal and they have quite a pronounced fragrance.

The var giganteum is the tropical species and ranges from the Fitzroy to the Endeavour Rivers. The flowers are usually larger, but not always, and have a slightly different colour pattern.

The plant does not lend itself readily to pot culture and should be mounted. I have it growing on Melaleuca and cork slabs, but best results have been with one mounted on a hardwood slab.

I find that it needs little more than 50% shade plus humidity and, of course, plenty of air movement. Protect from frosts. Fertilise in the growing period with foliar fertiliser at half recommended strength. A number of interesting hybrids have been produced using D. tetragonum as one of the parents. They mostly flower well and have reasonably large flowers.

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Rescuing Apparently ‘dead’ Orchids

By Brendan Killen

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Dockrillia linguiformis (Sw) 1800 Brieger

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