Selected Species - by Peter Taylor

Dendrochilum wenzelii Ames

IT is ironic that the delicate and charming genus was first described in 1825 by Karl Ludwig Blume, one of the most vain possessive and aggressive of the pioneers of orchidology in the early Nineteenth Century. Blume's personality was certainly worlds apart from the 'personality' the plants and flowers of Dendrochilum which today are popular, even among 'conservative' and 'traditional' orchid growers. I noted with interest at the recent AOC Orchid Conference in Port Macquarie that Dendrochilum convallariaeforme elicited as much interest and discussion as the majestic phragmipediums, paphiopedilums and cymbidiums on display.

My sources for the brief notes on the selected species for this month, Dendrochilum wenzeliiare the following and for more detailed analysis of wonderful D. dewindtianum and D. grandiflorum.

the genus I strongly recommend them to you. Banks & Cootes (1995, Orchids Australia, June & August editions), Banks & Cootes (1997 American Orchid Society June & August editions) Cootes, Jim (Orchids of the Philippines), and J. J. Wood (2001, Dendrochilum of Borneo).

Dendrochilum is in the Coelogyninae sub-tribe and De Vogel (1989) suggests that the genus may have evolved from Pholidota, section. Acanthoglossum which is primarily found in Borneo. There are approximately two hundred and seventy recognised species distributed from Burma southeast to Thailand, Malaysia, Borneo and Indonesia, Taiwan and the Philippines. Only two species are recorded from New Guinea. Populations of the genus are often isolated to a particular mountain and Cootes records that of the ninety six Philippine species, 94% are endemic with 85% of the species located in Luzon. In Borneo thirty two of the eighty one Bornean species are located on Mt. Kinabalu - if only the wonderful D. dewindtianum and D. grandiflorun were available from this locality!

Jeffrey Wood maintains that the isolated Dendrochilum populations on mountains may explain the high level of endemicity within the genus. Many species are restricted to a single mountain. I found Wood's theory as to the lack of Dendrochilum numbers in New Guinea (only two species) interesting. He postulates that two factors may influence this. First, long-range dispersal of dust-like Dendrochilum seed by wind did not result in effective colonization in New Guinea; second the mycorrhizal relationship in many Dendrochilum species may be particularly host specific and particular fungal partners are, or were, absent on this island.

Of my twenty or so Dendrochilum species, the selected species, D. wenzelii isa standout. It is easy to grow, reliable in flowering and an attractive plant when not in flower.

Jim Cootes records that the species was named by the great American orchidologist, Oakes Ames, after a C. A. Wenzel in 1915. The type specimen was collected on Mount Canayan on Luzon (Philippines) in 1913.

The species is characterized by its very leathery leaves, of approximately 30cm in length by 7mm in width; small pseudobulbs are about 25mm long. The semi-arching inflorescences appear with the new growth and flowering occurs in mid-winter. The only clone of the species that I have is that pictured in the accompanying photograph, a delightful deep red. However the species is variable in colour and Jim Cootes (The Orchids of the Philippines) has two excellent photographs of a lovely yellow and brown form. The shape of the flower is consistent.

Dendrochilum wenzelii is endemic to the Philippines where it is found in limited distribution on mountains in Luzon, the Visayas and Mindoro. It is an epiphytic species found at elevations above 1000m.

The prolific flowers are best seen close-up and there is an outstanding photograph of D. wenzelii in the August 1977 edition of Orchids, the magazine of the American Orchid Society (P803). The beautiful colour and crystalline texture of the flowers clearly reveal this as a 'must have' species.

The cultivation of this species is relatively easy (as is the case with most dendrochilums.) They are mountainous plants that require good humidity, shady and moist conditions and good air movement. In Port Macquarie my specimen grows well in a shade house with two layers of 50% shade cloth in summer and one layer of 50% shade cloth, plus a plastic house cover in winter.

I use plastic pots with excellent drainage and after experimentation with various bark mixes, I have settled on good quality sphagnum moss mixed with granulated polystyrene (70% sphagnum: 30% polystyrene.) I also 'crock' pots around the drainage hole with polystyrene. I find that this mix provides both stable moisture plus good drainage for the roots. Dendrochilum wenzelii and the related D. javieri are grown suspended above the benches. I am also experimenting with a division of D. wenzelii mounted on wet, tight-fibre treefern. So far so good, but the mount has to be kept moist.

Dendrochilum wenzelii seems to be cold tolerant and has experienced temperatures this winter of 5°C with no ill effect. Remember to keep the plants drier when the temperatures are low. The heat of last summer caused some problems to other species in my collection but the dendrochilums, kept shady, moist and as cool as possible, all survived.

Dendrochilum species are in general, and D. wenzelii in particular are orchids that are space efficient, of relatively easy culture and have most charming flowers (admittedly, small ones like D. pulcherrimum need to be viewed VERY close up to be appreciated.) As Jim Cootes maintains, it is a 'lovely genus' and you really should allow a few species to grace your shade house.

© Peter Taylor and Australian Orchid Council Inc 2006

Originally published in "Orchids Australia" October 2006.