Didymochlamys Hook.f. (Rubiaceae: not assigned to subfamily or tribe)
Charlotte M. Taylor [webpage]
Missouri Botanical Garden
P.O. Box 299
St. Louis, MO 63166
Didymochlamys Hook.f. includes 2 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.
Click on the images below to see a larger image
Didymochlamys whitei in western Colombia
The inflorescences of Didymochlamys are distinctive, with a
short fascicle of 2-5 flowers enclosed in two complanate enlarged green
bracts (the genus name refers to these bracts). The relatively small
flowers are white often tinged with 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
D. connellii are reportedly later dehiscent though at the apex
(whether this dehiscence is loculicidal or septicidal is unreported).
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.
Steyermark (1967) did review this genus, but quite briefly. Steyermark
(1974) presented a floristic treatment for D. connellii in
Venezuela and an illustration [1974(1): p. 428, fig. 70]. Dwyer (1980)
presented a floristic treatment of D. whitei in Panama and
illustration (1980: p. 148, fig. 33), but incorrectly called the
Panamanian plants "D. connellii".
Key to the Species of Didymochlamys
- 1. Larger leaves 2-4 x 0.4-1 cm; peduncles 1-3 mm long;
- 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...
- 1. Larger leaves 3-7.5 x 0.5-1.4 cm; peduncles 5-25 mm long;
- 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
- Dwyer, J.D. 1980. Part IX. Family 179. Rubiaceae. In: R.E.
Woodson, Jr. & R.W. Schery, Flora of Panama. Ann. Missouri Bot.
Gard. 67: 1-522.
- Steyermark, J.A. 1967. Didymochlamys. In: B. Maguire
& Collaborators, The botany of the Guayana Highland-Part VII. Mem.
New York Bot. Gard. 17: 290-291.
- Steyermark, J.A. 1974. Rubiaceae. In: T. Lasser, Flora de
Venezuela 9(1-3): 1-2070.
- Taylor, C.M. 2001. Rubiaceae. In: W.D. Stevens et al., Flora
de Nicaragua. Monogr. Syst. Bot. Missouri Bot. Gard. 85(3):
List of Names and Synonyms of Hillia
Further information on these names can be found in the TROPICOS
Didymochlamys connellii N.E. Brown, southeastern Venezuela
to Guyana, 350-1100 m
Didymochlamys whitei Hook.f., southern Nicaragua to western
Text and Images, unless otherwise indicated, Copyright © by Charlotte M. Taylor. All rights reserved.
This page was revised on April 8, 2008.