By Jim Cootes and Ronny Boos
A s we have mentioned previously, in these articles about different orchid genera and their species, the larger genera, such as Dendrobium, Bulbophyllum, etc, are divided into sections of similar and/or closely related species. Many of these sections have characteristics by which these sections, in due course, could become genera in their own right.
The genus Dendrobium, as represented in the Philippines, when taken in the broad sense has about 18 sections, a number of which could be elevated to generic status.
Section Calcarifera was first proposed by the Belgian botanist Johannes J. Smith in 1908, in the Bulletin du Jardin Botanique de Buitenzorg. The Sumatran Dendrobium pedicellatum, was designated as the type species for the genus when the section was firstproposed. Species that belong to this section can be characterized by the pendent inflorescence(s), on which the flowers face all directions; and the pedicel (the stalk of a single flower) is at right angles to the mentum (spur.)
From our observations of this section the species can be divided into two groups: the first group having upright, to semi-pendulous growth habit, where the numerous flowers face in all directions; the second group has plants which are totally pendulous, and the blooms are usually produced singly or in pairs. In this article we are commenting on the first group, and will cover the second group in the weeks to come.
There are almost 100 species in this section and they have their centers of distribution in the mountains of Sumatra, Borneo, and the Philippines. Here in the Philippines there are about 20 species in the section all of which are endemic, therefore occurring in no other place on earth. This latter fact is something of which all Filipinos should be very proud, but sadly the destruction of the habitat of these orchids, and every other inhabitant of the forest, continues on, unabated.
Dendrobium cerinum has only been recorded from the province of Rizal, but it is, without a doubt, more widely distributed throughout Luzon. There are two color variations of the labellum: one which is plain, golden yellow, and the second form which has two red “eyes” near the base.
Dendrobium fairchildiae is known from the Mountain province, Nueva Ecija, Nueva Vizcaya, and Rizal on Luzon; and the island of Catanduanes. It grows as both an epiphyte, and on rocks, at high elevations. There is also a pure white form of this beautiful species. Plants can reach more than a meter in height.
Dendrobium guerreroi is recorded from the island of Mindoro; the island of Dinagat; and has recently been found in the province of Bukidnon in Mindanao. It grows epiphytically at elevations up to about 600 meters.
Dendrobium ionopus is one of the most variably colored species in this section. It has been found in the provinces of Bataan, Benguet, Nueva Ecija, Nueva Vizcaya, and Rizal in Luzon; and the island of Negros in the Visayan Sea. Color can vary from pale brown to yellow, to green, and there is even a pure white form. This is a species from higher elevations.
Dendrobium phillipsii could be considered the sister species of Dendrobium fairchildiae. Dendrobium phillipsii is only known from the province of Bukidnon on Mindanao, but may be more widely distributed on the island.
Dendrobium profusum is another beautifully variable species, color-wise, and is only known from the eastern provinces of Luzon.
Dendrobium ravanii was only described in 2008, from plants found at medium elevations on the island of Mindoro. Quite frequently this species grows close to the ground.