John L. Clark is Aldo Leopold Distinguished Teaching Chair in the Science Department of The Lawrenceville School, Lawrenceville, NJ, USA. He has published widely on the Gesneriaceae, reporting his collecting excursions and scientific analyses.

Gesneriads are botanical jewels of the Caribbean flora. Their broad range of flower shapes and colors do not conform to traditional generic concepts. Habits range from terrestrial shrubs that are more than two meters tall (Fig. 1A) to miniature rosettes that are smaller than a human palm (Fig. 1B), to obligate lithophytes (restricted to rocks or cliffs). Eccentric flower colors are represented by Gesneria heterochroa, which has green corolla tubes with white lobes (Figs. 1C & D), and Gesneria clarensis, which has orange corolla tubes with green lobes (Figs. 1E & F).

The entire Caribbean Gesneriaceae could be considered a taxonomist’s nightmare because of ongoing changes in classification. Likewise, this group is a cherished dream for evolutionary biologists because of convergent evolution, remarkable patterns of species diversification, and a broad range of plant-pollinator interactions. A goal of this article is to share information about Gesneria and Rhytidophyllum, the dominant genera of Caribbean Gesneriaceae. I will describe recent classification changes, and highlight those changes with images, many of which are documented here from live material during recent exploratory research expeditions. A more comprehensive background on the classification of these two genera is found in Wiehler (1983) and Skog (1976). Skog’s Ph.D. dissertation focused on a comprehensive taxonomic treatment of Gesneria (Skog 1976) that included field expeditions in 1970 to Puerto Rico, Dominica, Dominican Republic, Haiti, and Jamaica. Important discoveries from those expeditions were described in The Gloxinian, now Gesneriads, by Skog and Talpey (1973).