Dendrobium speciosum (Dendrocoryne: Orchidaceae) complex in north Queensland
Peter B. Adams A B , Jacinta M. Burke A and Sheryl D. Lawson AA School of Botany, The University of Melbourne, Vic. 3010, Australia.
B Corresponding author. Email: gallangowan@optusnet.com.au
Australian Systematic Botany 19(3) 259-271 https://doi.org/10.1071/SB05030
Submitted: 7 October 2005 Accepted: 6 March 2006 Published: 30 June 2006
Abstract
Dendrobium speciosum Sm. has received insufficient taxonomic study north of St Lawrence, Queensland, where plants display much morphological variation in diverse habitats. Two varieties have been described previously, variety pedunculatum, occurring north of Townsville, and variety curvicaule for plants between the Connors Range south of Mackay and Annan River, south of Cooktown. In this multivariate analysis of 107 representative plants sampled from areas between St Lawrence and Cooktown, cluster analysis and principal coordinates analysis, were used to categorise the variation. Three overlapping varieties are revealed. North of Townsville variety pedunculatum intergrades with a medium-to-tall rainforest form, which separates with a small overlap in analyses from variety curvicaule plants south of Townsville. We formally describe these rainforest forms, previously referred to as variety curvicaule, as a new variety, Dendrobium speciosum variety boreale, which occurs between Cooktown and Mt Elliot, south of Townsville. Variety boreale is characterised by the presence of a collum in most individuals, medium to long pseudobulbs, large, wide leaves, long pedicels, and fairly uniform off-white to cream flowers. Dendrobium speciosum variety curvicaule Bailey is shown to be a name of uncertain application, and is neotypified to apply to the southern group of north Queensland plants, which occur between St Lawrence and Mt Dryander and on the Whitsunday Islands. Variety curvicaule is characterised by pseudobulbs that are of medium length, wide base and have an inconspicuous collum. The flowers have relatively wide segments in relation to all other varieties, long wide petals and incurving lateral sepals.
Acknowledgments
We thank the Queensland Parks and Wildlife Service for permits to study plants. Bruce Gray, Jim Bataldo, John Nuss and Noel Grundon assisted in the fieldwork, and Pauline Ladiges, Bill Lavarack and Geoff Stocker critically reviewed the manuscript drafts. Thanks also to Jim Ross and Neville Walsh (Royal Botanic Gardens, Melbourne) and staff of Royal Botanic Gardens, Sydney, for assistance with taxonomy and Latin diagnosis. Stuart Gardner and Malcolm McGowan provided computer assistance.
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