As I walk through the forest I often see orchid plants
growing in the trees. Most of them are
in predictable places where one would expect an orchid plant to survive and
thrive. But sometimes our expectations
turn out to be wrong. When I have found Tolumnia variegata growing in the Rio
Abajo forest it has usually been growing in twigs under the shelter of the
canopy. But last week I found a group
of plants growing in a leafless branch of an orange tree. Far from been protected by a leafy canopy
this group of plants is exposed to the worst of the tropical sun for most of
the day. From the orientation of the
plant I surmise that the original plant germinated and grew in the underside of
the branch. But all the leafy growths
are now on top of the branch, fully exposed to the sun
.
The leaf fans are flat and are so oriented that at midday
only the very narrow top of the leaf is exposed to the sun. This orchid has a large network of roots that
runs for many inches around it in the branch where it is perched. The leaf fans are comparatively puny compared
with other Tolumnia I have seen in
the forest and are definitely stunted.
The inflorescences are small and have fewer flowers than plants that
grow in more sheltered spots. However
the plant looks pretty healthy and it has several inflorescences on the way.
The plant is growing fifteen feet up in a tree. I plan to monitor its growth and blooming
over the next year. I am particularly
curious to see how this plant fares in such an exposed location during the dry
season when a whole month can pass without any rain and humidity can be very
low for our location.
On occasion I have brought Tolumnia plants that have fallen from the trees to my shadehouse
which is not far from where this tree is located. All have eventually died. I wonder why a plant that lives several years
on the local trees around my house perishes when moved to my garden. Perhaps observing this plant will illuminate
this question.
