Quinine

This species is considered native in the mountains of northern Costa Rica through Panama, and the Andes of Colombia and Venezuela south to Bolivia, at 600-3300 m. This species is also an invasive weed in some tropical islands, in particular the Galapagos.

This species is a tree of cloud forests with showy white to pink flowers and capsular woody fruits. This is the most commonly collected species of Cinchona as well as having the broadest geographical and ecological ranges. It is variable morphologically, and its separation from other Cinchona species has sometimes been difficult. Andersson (1998) clarified the taxonomy of this genus and noted, as discussed further in the notes for this genus, that many species of Cinchona including this one hybridize locally to produce populations that are difficult to assign to a particular species.

Cinchona pubescens is one of the main commercial sources of the antimalarial febrifuge quinine, which is found in commerically usefl quantities in its bark. Quinine is produced from cultivated trees not only of this species, but also of Cinchona calisaya and numerous hybrids between these and some other Cinchona species.

This species has not yet been evaluated formally for its conservation status. Currently the conservation status evaluations of plant species from the New World Tropics are being done country by country, and because it is not feasible to evaluate all the species, the work is being done in prioritized steps. The first priority group, now being assessed, is the plant species that are endemic to a single country, or known from only a very few specimens or observations and thus apparently rare. Cinchona pubescens grows naturally in at least seven different countries and does not appear to be particularly rare, and seems likely to qualify for the IUCN category of Least Concern (LC) when it is eventually evaluated.

Trees or shrubs up to 10 m tall; branchlets pilosulous, tomentulose, or puberulous or rarely glabrescent. Leaves with blades elliptic, broadly elliptic, ovate, or suborbicular, 5-15 x 2-10 cm, drying membranaceous to thinly papery, densely tomentulose or pilosulous to puberulous or rarely glabrescent, at base cuneate to truncate or occasionally subcordate, at apex rounded to obtuse; secondary veins 7-11 pairs, without domatia or these reduced; petioles 1.2-5 cm long, densely pubescent or occasionally glabrescent; stipules obovate to ligulate, 12-26 cm long, variously pubescent or rarely glabrescent, at apex subacute to usually broadly rounded. Inflorescences 5-25 x 5-25 cm. Flowers with hypanthium 1.8-3.3 mm long, densely pilosulous to tomentulose or puberulous; calyx limb 1.3-2.8 mm long, lobed for up to 1/3 of its length, the lobes triangular, acute; corolla salverform, white or usually pink to purple, outside pilosulous or strigillose or occasionally glabrescent, inside densely pubescent in throat and on lobes, tube 9-14 mm long, lobes triangular, 4-6 mm long, acute; anthers 2.8-3.9 mm long; stigmas 1.5-4 mm long. Fruits capsular, narrowly ellipsoid to nearly cylindrical or sometimes lanceoloid (i.e., widest below the middle), 13-41 x 5-7 mm, stiffly papery, dehiscent from the base (or sometimes immature capsules opening prematurely also from the apex); seeds 8-12 x 2-3 mm, flattened, small, irregularly elliptic to oblong, marginally winged and often irregularly incised or erose.

High-resolution scans of representative museum specimens for reference are available (along with technical taxonomic information) at TROPICOS: Cinchona pubescens.

The fruits are dry, rather woody capsules that open to release numerous small, papery, flattened seeds that are dispersed by the wind.

The flowers are diurnal, and white, pink, or purple and generally very hairy or fuzzy in the mouth of the corolla tube. They are apparently pollinated mainly by butterflies and hummingbirds. The flowers are distylous (see the comments under the genus Cinchona for explanation).

In a large greenhouse at the Missouri Botanical Garden in St. Louis, Missouri, there grows a slender sapling of Cinchona pubescens, a tree that has played a remarkable role in human history. Journeying to this artificial tropical forest under glass, Ari Daniel Shapiro asks curators Carmen Ulloa Ulloa and Charlotte Taylor just what makes this famous “fever tree” special. He also learns how it’s possible to open a three-hundred-year-old bundle of dried plant specimens and disappear—happily—into the past.

Listen to the podcast and meet the scientists on the Learning + Education section of EOL.