I am looking for information or other references with respect to whether the pollinator has been
identified and studied for Den. cruentum or similar species in Section formosae (e.g., Den. suzukii,
Den. tobaense, Den. ayubii, Den cariniferum). In addition, I would like to know more about the
function of the intense red color and the structure of the lip of this and related species.
Words cannot do justice in providing a description of the lip of Den cruentum. It has multiple red
lobes and a red throat with a heavily-textured center crest having intensely red-colored ridges.
The lip looks like it has been carefully decorated using red lipstick. The hinged lip is also of
very heavy substance, having a stiff, plastic-like quality. Many of the Section formosae
Dendrobiums share these qualities, but Den. cruentum, Den. suzukii (the giant cruentum, which may
not be a separate species), and Den. tobaense are the most alike in this regard.
It may be that D. cruentum, like the vast majority of orchid species, doesn't have an identified pollinator. However, it has a couple of characters that suggest it is bird pollinated. Red is a color that attracts birds (often used in the US to attract hummingbirds - I'm not sure what the counterpart would be in Thailand, honeycreepers?). Insects, on the other hand, are usually unable to see red. The thick, plastic-like lip is also consistent with bird pollination, said to be important to avoid damage from the sharp, stiff bill of the bird. Maybe one of our SE Asia experts will tell us more specifically what pollinates this group of Dendrobiums (David Banks, Peter O'Byrne, others?).
-- Steve Beckendorf Berkeley, California
_______________________________________________ the OrchidGuide Digest (OGD) [EMAIL PROTECTED] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
