Substrate preferences of 87 taxa in Calymperes, Mitthyridium, and Syrrhopodon (Calymperaceae), as determined from label data on herbarium specimens, vary at the generic level as well as among the specific and subspecific taxa. The bark of trees and lianas is the most preferred substrate. Mitthyridium is most constant to the bark substrate, followed by Calymperes and then Syrrhopodon. Nineteen taxa of Syrrhopodon (38% of the 50 taxa studied), 14 taxa of Calymperes (50% of the 28 taxa studied), and six taxa of Mitthyridium (67% of the nine taxa studied), were 50 percent or more constant to bark; this trend reflects the presumed direction of evolutionary specialization of the genera. Preference for other substrates varies according to genus: rock is the second most common substrate for Calymperes, and dead wood is second for Mitthyridium and Syrrhopodon. The tree base habitat is also of importance for the three genera. Soil as a substrate is of least importance for Mitthyridium (a sample of one taxon collected on soil), intermediate for Calymperes (samples of 10 taxa: 36% of the 28 taxa), and of greater importance for Syrrhopodon (samples of 30 taxa: 60% of the 50 taxa).