What does morphology tell us about orchid relationships? - A cladistic analysis

A cladistic analysis of Orchidaceae was undertaken for 98 genera using 71 m orphological apomorphies based on a reconsideration of previous character a nalyses and newly discovered variation. The equally weighted analysis found 60 000 most parsimonious trees with low consistency (CI = 0.29) but high r etention (RI = 0.83). The strict consensus reveals a significant amount of structure, and most traditionally recognized subfamilies are supported as m onophyletic, including the Apostasioideae, Cypripedioideae, Spiranthoideae, and Epidendroideae. Orchidoideae in the broad sense are paraphyletic, givi ng rise to spiranthoids. Vanilloids are sister to epidendroids, although ex hibiting several states otherwise found only in clearly basal groups, such as Apostasioideae. The nonvandoid epidendroids are poorly resolved, due to a high degree of homoplasy. The vandoids appear to be monophyletic, contrar y to recent molecular evidence, possibly due to repeated parallel developme nt of the vandoid character suite. The importance of vegetative characters as evidence putatively independent from floral features is demonstrated in the placement of Tropidia. Implied weighting analysis of these data resulte d in similar patterns at high levels, although the Orchidoideae and Spirant hoideae may each be monophyletic and the nonvandoid epidendroids are more r esolved. The high degree of structure implied in previous orchid classifica tions must be reconsidered, given the poor resolution at lower levels in th e present trees.