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Published In: Hooker's Icones Plantarum 12: 21–22. 1876[1872]. (Aug 1872) (Hooker's Icon. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 10/8/2009)
Acceptance : Accepted
Project Data     (Last Modified On 2/21/2019)

Didymochlamys Hook.f. includes two species of small, usually epiphytic herbs found in northern South America and southern Central America. These plants grow on boulders and tree trunks in wet forests, and are often overlooked as Rubiaceae. Their leaves are distichous and opposite but strongly anisophyllous, and may appear alternate if not examined carefully. The interpetiolar stipules of Didymochlamys are quite small and quickly caducous, so that the smaller leaf of the anisophyllous pair may be mistaken for a stipule, and Didymochlamys is therefore sometimes confused with Gesneriaceae.

The inflorescences of Didymochlamys are distinctive, with a short fascicle of 2-5 flowers enclosed in two enlarged green bracts that are held pressed flat together; the genus name refers to these bracts. The relatively small flowers are white to blue or violet, and their lobes have the margins crisped to incised or appendaged. The cupuliform fruits are berrylike at least in their early stages, although those of Didymochlamys connellii are reportedly later dehiscent though at the apex. The numerous seeds are small and bear a tuft of silky trichomes at one end, similarly to the seeds of Hillia Jacq.

The relationships of Didymochlamys within the Rubiaceae are not yet clear, and this genus has never been studied in any detail. It has generally been associated with genera now included in Cinchonoideae, but it has raphides in its tissues; these are found throughout the genera of Rubioideae, but only in a few genera of Cinchoneae. The Cinchonideae tribe that is notable for its raphides is Hillieae, which includes a number of epiphytes. The unusual seed form of Didymochlamys is only otherwise found in Hillia, and it may have its relationships in this tribe.

Steyermark (1967: pp. 290-291) did review this genus but only briefly. Steyermark (1974) presented a floristic treatment for Didymochlamys connellii in Venezuela and an illustration (1974: p. 428, fig. 70). Dwyer (1980) presented a floristic treatment of Didymochlamys whitei in Panama and an illustration (1980: p. 148, fig. 33), but incorrectly called the Panamanian plants "Didymochlamys connellii".

Author: C.M. Taylor
The content of this web page was last revised on 20 March 2014.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml


Neotropics: in wet lowland forests at 100-1100 m, one species southern Nicaragua to northwestern Ecuador and the other in southern Venezuela to Guyana.



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Key to Species of Didymochlamys

1. Larger leaves 2-4 x 0.4-1 cm; peduncles 1-3 mm long; inflorescence bracts elliptic to ovate, 1-1.5 x 0.5-1 cm; calyx lobes 2-2.5 mm long; corolla tubes 12-14 mm long; corolla lobes 3-4.5 mm long, subentire or with two elongated appendages... D. connellii
1. Larger leaves 3-7.5 x 0.5-1.4 cm; peduncles 5-25 mm long; inflorescences bracts ovate, 1-2 x 1-2 cm; calyx lobes 4-5 mm long; corolla tubes 13-14 mm long; corolla lobes 1.5-2 mm long, the margins irregularly incised to appendaged throughout, the appendages up to 2 mm long...D. whitei
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