Dendrobium trilamellatum var. trilamellatum
CLICK ON THE IMAGES ABOVE TO EXPAND AND VIEW
Variety trilamellatum is the horticulturally superior of the two varieties of Dendrobium trilamellatum as I have referenced them on this website. For a brief history of this species, how I have distinguished the two varieties and a description of the alternate variety Dendrobium trilamellatum var. semifuscum click HERE.
Dendrobium trilamellatum var. trilamellatum grows long slender, fusiforme (swollen to the centre) pseudobulbs to about 50cm-60cm. Leaves are typically 3-5 per cane, but sometimes more. Compared to var. semifuscum the leaves are possibly slightly broader and less succulent. Plants do grow into rather large clumps (many leading growths) in some situations. The plants in the populations I have observed do not grow as large as the largest var. semifuscum – though I have no experience of var. trilamellatum from the Torres Strait, New Guinea or the Northern Territory (which may differ on this characteristic). Dendrobium trilamellatum var. semifuscum grows into drier and harsher habitats than var. trilamellatum and plants there are rather stunted. However where they occur in higher rainfall areas (e.g. around Cooktown), var. semifuscum develops into quite large plants that in my observation are significantly larger than var. trilamellatum.
Dendrobium trilamellatum var. trilamellatum start flowering from a small size and is quite common to see plants with only a couple of leafed bulbs to barely 10cm in height already flowering. It seems from my observations to start flowering at a significantly smaller size than var. semifuscum. Compared to variety semifuscum, the flowers are larger (up to 6cm-7cm in size), broader, circular in shape and more evenly coloured. The labellum is much broader. Flowering season is also Spring, and the flowers are sweetly scented. Spikes generally attempt to grow upright, but often flop over with the weight of the flowers, which number to about 12 or so per raceme.
Differences in flower form do occur across areas and some are narrower in their parts and also more tightly ‘curled’. Plants from the offshore islands of the Northern Territory are reported to be yellow, instead of the coffee/ caramel colour. Within a region, however, plants are relatively similar (at least to my eye) without anywhere near the degree of variability that is seen within some populations of Dendrobium canaliculatum.
For general purposes, the image below displays the two varieties side-by-side.
Side-by-side image of: (Left) Dendrobium trilamellatum var. trilamellatum; (Right) Dendrobium trilamellatum var. semifuscum.
Dendrobium trilamellatum var. trilamellatum occurs in the higher rainfall east coast areas of North Queensland from McIlwraith Range north into the Torres Strait, Papua New Guinea and West Papua. Orchids of New Guinea note that is recorded in the lowlands directly above the Torres Strait in both Papua New Guinea and West Papua, and that it has recently been recorded from the base of the Bird's Head Peninsula (Doberai) - a significant extension of its previous range. It is also found in the far north of the Northern Territory – the only 'Tea Tree Orchid' other than Dendrobium canaliculatum var. foelschei to be found there.
Plants grow on a variety of trees particularly beside watercourses and hillside low forests where fire rarely penetrates. The growing niche of this variety is roughly between that of Dendrobium johannis (generally shadier and moister positions) and Dendrobium trilamellatum var. semifuscum (generally drier and brighter positions). However there is considerable overlap here and these growing position descriptions are in no way absolute.
Where this orchid finds suitable habitat it can be incredibly abundant. I recall a thin, hillside forest beside a swampy creek in the Iron Range where thousands of these plants were in flower. They grew on fallen branches, at chest height on small tree trunks to branches high in the canopy near the creek. Flowers of this variety can be quite large and their abundance on this occasion made for a memorable walk.
Dendrobium trilamellatum var. trilamellatum is a relatively common species in cultivation - at least in Australia. Due to its superior floral characteristics it is more commonly cultivated than var. semifuscum. Both varieties are quite easy to grow. Some plants in cultivation are difficult to distinguish as particular varieties and may be intervarietal crossings. Some are clearly of hybrid parentage (but incorrectly labelled as species). As a parent of hybrids, there has not been differentiation between the varieties although some earlier hybrids were registered with the previous species Dendrobium semifuscum and then changed to Dendrobium trilamellatum (and in some cases both semifuscum and trilamellatum were registered against another parent and so now two valid hybrid names exist for the same hybrid of trilamellatum). There has also historically been confusion in registration with Dendrobium johannis registered as trilamellatum and vice versa.
A more scientific description of Dendrobium trilamellatum var. trilamellatum (as Cepobaculum trilamellatum) adapted from M.A.Clem. & D.L.Jones, Orchadian 13(11): 486 (2002) can be accessed from the Australian Tropical Rainforest Orchids website by following this LINK.