Osa pulchra (Rubiaceae)

Osa pulchra (Rubiaceae)

Osa (Coffee Family)

Origin: Costa Rica, Panama

Perhaps one of the rarest plants not only in cultivation but also in the wild, the Osa pulchra isknown from only two populations in Costa Rica, with a total of less than thirty individuals, and a recentlydiscovered population in Panama. Due to the Costa Rican plants’ proximity to human habitation,botanists have been hesitant to declare them naturally-occurring, thinking they may have been bred byhumans long ago, much like the brugmansias, which are commonly cultivated plants but of which nowild-growing populations exist. The recent Panamanian find, however, solidifies the monotypic genus asthe real deal.

Many plants in the Rubiaceae family have small, star-shaped flowers, held by short pedicelsclose to the plant. The Osa, however, has large trumpet-shaped flowers, similar to many plants in theSolanaceae (e.g., Brugmansia, Solandra), which are pendent, borne on long pedicels, and have fusedpetals. Giant, white, and fragrant at night, this bloom is the showstopper to end all showstoppers.

Growing an Osa is a major commitment. Since most of the known plants in cultivation are grownfrom a single seed pod brought to the U.S. through the Missouri Botanical Garden in 1996, there areissues with genetics and seed viability. This situation may be markedly improved by the introduction ofgenetic material from the newly-found Panamanian population. We shall see.

In the meantime, if you want to see an Osa pulchra in glorious flower, get thee to our Tropical Conservatory in the next few weeks, and don’t forget to bring your camera. There are only a few botanical gardens in the world that have one, and we are proud to be one of them.

Text by David Troxell