Manila Bulletin

Confused Species

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We wrote our first article, about commonly confused orchid species, on August 28, 2016. In this previous article we discussed Dendrobium bursigerum and Dendrobium secundum; and Eria javanica and Eria sessilifol­ia. It is with great pleasure that we can now reveal that Dendrobium secundum does occur naturally on the north-east coast of Mindanao. It was recently found, in full flower, on felled trees. There is absolutely no doubt now that Dendrobium secundum does occur in the Philippine­s. The subjects for this week’s article are three Philippine endemic Dendrobium species, which are found at high elevations. The species concerned are Dendrobium victoriae-reginae, Dendrobium ceraula and Dendrobium yeageri. These three species are all members of section Calcarifer­a, where, in our opinion, they take an isolated position. Firstly, the flowers do not have long spurs which are so obvious in species like Dendrobium guerreroi and Dendrobium ravanii, and the internodes of the pseudobulb­s are short and tapered, whereas in other species they are parallel and usually longer. Another feature of this particular section is the (usual) flowering on leafless pseudobulb­s, which should only be removed when in a completely dried-up state.

Dendrobium victoriae-reginae is by far the most widely distribute­d of the three species and it has been recorded from the provinces of Ifugao, the Mountain province, Nueva Ecija, Nueva Vizcaya, Pampanga and Quezon on Luzon; the island of Mindoro; the island of Negros in the Visayan Sea; Camiguin Island to the north of Mindanao; and the provinces of Bukidnon and Davao on Mindanao. It is usually found at elevations of above 1,300 meters, where it grows as an epiphyte, amongst deep mosses, on the trunks and branches of rough-barked trees. The habitat is usually humid, and there is always constant air movement. One of the most wonderful features of Dendrobium victoriae-reginae, is the great color range of the flowers. The blooms can range in color from deep blue, to sky blue, to lavender, to pure white. There is also considerab­le variation in the density of the striping on the floral segments. It was named by Augustus Loher, in 1897, and the specific epithet honours Queen Victoria, who was about to celebrate her sixtieth anniversar­y on the throne of Great Britain. The spur can be seen in the bottom picture of the collage.

Dendrobium ceraula, which is also known as Dendrobium gonzalesii, is of limited distributi­on, and has only been recorded from the mountains of the southern province of Albay, on Luzon. Even though Dendrobium ceraula is similar to Dendrobium victoriae-reginae, it is easily separated by the shape of the mentum (spur), which curves upwards and towards the front of the bloom. This feature gives rise to the specific epithet, which means horn-blower or trumpeter. The mentum of Dendrobium victoriaer­eginae points straight backwards. Usually the flowers of Dendrobium ceraula are slightly larger than those of Dendrobium victoriae-reginae. The color range of Dendrobium ceraula varies from milky white, to pale blue, to pink. The most noticeable striping is on the labellum. The spur can be seen in the bottom picture of the collage. The spurs can be seen in the top picture of the collage.

Dendrobium yeageri is most similar to Dendrobium victoriae-reginae, and is only known from high elevations in the mountains of central Luzon. The main separating feature is the color of the flowers, which in Dendrobium yeageri are from lavender to pink. The striping on the blooms is also less obvious. The spur is marginally smaller. We believe that upon critical examinatio­n, and comparison of the two species, it is most likely that

Dendrobium yeageri will become a color form of Dendrobium victoriae-reginae, if not a synonym. The spur can be seen in the picture of the species.