Analysis of Morphological Variation in a Field Sample of Caladenia catenata (Smith) Druce (Orchidaceae)

Abstract

A morphometric analysis of the variation among 24 attributes of a field sample of 71 plants of the Caladenia catenata (Smith) Druce species complex from the Sydney region suggests that there are two phenetically distinct polythetic taxa within this orchid group. These taxa correspond with the traditionally circumscribed taxa C. alba R. Br. and C. carnea R. Br. but no exclusive or 'key' attribute could be found to discriminate between them. The morphological distinction between these taxa is correlated with habitat differences characterized by soil properties and species associations. However, some of the C. alba sites are ecologically intermediate between the 'extreme' C. alba sites and the C. carnea site, and these sites contain a number of C. alba individuals with some attributes traditionally thought to be diagnostic of C. carnea. We interpret this character distribution as being the result of introgression of some C. carnea attributes into a population of C. alba.