The Western Hemisphere gesneriads almost all
belong to the Gesnerioideae.
They have symmetrical cotyledons,
unlike the Didymocarpoideae.
Most of them are pollinated by hummingbirds, and others are pollinated by
A special pigment type
is found in most genera of this subfamily.
These pigments are bright red or yellow, and are associated with
The gesneria tribe
(genera Gesneria, Rhytidophyllum, Bellonia)
is found mostly on the islands of the Caribbean.
The sinningia tribe is found mostly in Brazil.
Other gesnerioid tribes are found in Mexico, Central America, and
northern South America.
Underground storage organs, like scaly rhizomes and tubers, are found in a
number of genera of the Gesnerioideae.
Recently, it has been proposed that the genus
Titanotrichum, from Taiwan and
eastern mainland China, is actually a member of the
The largest subfamily of the
is, except for one species, confined to the eastern hemisphere.
[But see below.]
It has two centers of concentration: South Africa and Madagascar
(Saintpaulia and Streptocarpus)
and Southeast Asia (all other genera).
The Didymocarpoideae are characterized by the
This subfamily includes two of the youngest and fastest-growing genera of
the family: Cyrtandra
Possession of berry fruit has allowed Cyrtandra
to colonize the (geologically young) islands of the Pacific.
It may be that the hairy seeds of Aeschynanthus
also contribute to its dispersal through the South Pacific
(over a range not as large as that of Cyrtandra).
Many (most?) aeschynanthus are pollinated by birds, although not by hummingbirds,
since hummingbirds are confined to the western hemisphere.
There is one character found in a number of widely separated genera
of this subfamily.
Streptocarpus, Boea, Paraboea,
and several others have long fruits which are spirally twisted.
This may be an innovation to facilitate seed dispersal.
When the fruit is ripe, it splits open and untwists, releasing the seeds gradually.
Since Streptocarpus is not closely related to the others
which have this trait and widely separated from them geographically,
this trait must have evolved separately in the two groups.
The late Hans Wiehler split off the tribe Coronanthereae
from the Gesnerioideae into a
separate subfamily, the Coronantheroideae.
Since tribal members Sarmienta and
Mitraria share a special pigment
with the Gesnerioideae, the chemical evidence
suggests that the Coronantheroideae might perhaps be an
entity multiplied without necessity.
Coronantheroids are native to the Pacific coast of Chile
Asteranthera) and islands of the South Pacific
In Mayer et al. (2003),
it was proposed that the tribe Klugieae,
comprising some species of unusual gesneriads, be removed from the
Didymocarpoideae to its own subfamily.
The largest genus in the tribe is
Monophyllaea, with perhaps 30 species.
The implication of the split (and the gist of the molecular data) is that
the Epithemateae branched off from the old-world gesneriaceae before any
further radiation of the latter into
and so on.
Furthermore, the surviving members of the subfamily
have evolved a long way since the split.
Thus this tribe is the relic of what was probably
a much more wide-spread and numerous group.
Most recent classifications have kept the Epithemateae
in the subfamily Didymocarpeae as a
sister group to the rest of the subfamily.
Most species of the Epithemateae
are found in southeast Asia.
One relic, Epithema tenue,
is found in western Africa.
This tribe also includes one species,
Rhynchoglossum azureum, found in Central America.
How it got there nobody knows, since it does not have a fruit
designed for long-range dispersal.
Perhaps not coincidentally, Rhynchoglossum
is sister to the rest of the
Rhynchoglossum contains about 10 species,
one of them (R. notonianum from southern India) close to R. azureum,
suggesting that the latter is a relatively recent immigrant to the neotropics.