DENDROBIUM | Herbarium Digital Library


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DENDROBIUM

Category: Plants and Orchids
Date Posted: 2006-10-16

OF THE ORCHID GENERA REPRESENTED IN THE PHILIPPINES, possibly one genus, that of Dendrobium, includes the greatest number of native species of horticultural value. Although, here may be more interest displayed by European and Ameri:an collectors and growers in the native plants of the genera Phalaenopsis and Vanda, the number of horticultural species >f these are limited to five and four, respectively, whereas ,here are at least eight indigenous Dendrobiums which produce exotic flowers and are worthy of a prominent position in collections.
Including the "botanical" Dendrobiums, those which produce small flowers of insignificant size, there are approximately eighty species of the six hundred odd members of this large Indo-Australian-Asiatic genus which are indigenous to the Archipelago, and of this quantity about seventy are endemic. Such a vast group as the Dendrobium is naturally a complex one. It was first recognized as a distinct genus by Swartz, the Swedish successor to Linnaeus in 1800, when he published the descriptions of a number of new genera, including Dendrobium. The generic name is derived from the Greek dendron, meaning "a tree," and bios, "life," possibly in reference to the manner in which so many members of the genus cling to the trees for support.

Various authorities have found it convenient to divide this large genus into natural sections distinguished by the prominent characteristics of allied members.* As a result of this systematic grouping, it is much easier to study the species and understand their interrelationship and cultural requirements.

The most important section of the native Dendrobiums is that of EUGENANTHE, a group of thick-stemmed plants with colorful flowers which includes the blood purple D. anosmum (superbum), the yellow D. heterocarpum (aureum) and the blue D. Victoriae Reginae. Of these three species, the first" two are also encountered in other parts of southeast Asia, whereas the latter, D. Victoriae Reginae, is endemic to the high mountains of the Philippines.

D. anosmum (superbum) is the largest flowered of the native species often producing flowers four inches across the petals. Besides the typical species, there is a variety called D. anosmum var. superbum and considerable confusion has resulted because of the nomenclature of these two types. The now recognized type, D, anosmum, is a plant with thickened stems about two to three feet long which has flowers about three inches across the petals but is not fragrant. The variety superbum, however, has stems four to six feet long and flow°rs four inches in diameter that are fragrant with the odor of , hubarb. The flowers of both types last about three weeks. Cuming discovered the first plants of what is now referred to as the variety, in the Manila area, about 1838. These plants, were sent to England and flowered in 1839. They were originally described and named D. macrophyllum, a name which could not be retained because it had been previously assigned to an entirely different Dendrobium. The smaller type was also introduced by Hugh Cuming from the same area and at that time was described as a variety of the larger type. At present, however, the name D. anosmum is applied to the small-flowered, non-fragrant type, and the variety, superbum, to the larger type. The specific name anosmum refers to the odorless flower of the type and the varietal name superbum describes the finer flowers of the variety.

This species and the variety can be collected from the low, hot valleys of central Luzon, where it is often associated with plants of Aerides quinquevulnerum and Anota violacea. It is also native to Bontoc, Lepanto, Nueva Vizcaya, Malay Peninsula, Celebes, Amboina, Borneo and New Guinea.

The second most important species of the same section 'EUGENANTHE is the polymorphous plant D. heterocarpum (aureum), an extremely variable species as presently understood in the Islands. This is a yellow-flowered plant with flowers about two to three inches across. Plants that are collected from Quezon (Tayabas) Province near Lucban have hanging -hickened stems about one-half of an inch in diameter and three to six feet long. Those from the mountains of northern Luzon are upright plants with thickened stems twelve to fifteen inches high. Each type of plant produces similar cream yellow flowers in clusters of three to six but those of the mountain plants are slightly smaller and darker than those of the Lucban area. Also the plants from the mountains flower during February and March, while those from Lucban flower during August and September.

This species is widely distributed throughout Southeast Asia, including India, Ceylon, Burma, Java, and Celebes, and was originally collected from the India area in 1837 where it was detected by Gibson. The first Philippine plants were another introduction of Hugh Cuming who found the plants on the Island of Luzon in 1842. The specific name heterocarpuna is the one at present officially recognized and means "various fruited," a term which appears vague, but may refer to the many seed pods produced by this species. The more common name, aureum, was one which was applied for many years, but had to be replaced by heterocarpum because of previous usage. The word aureum refers to the golden appearance of the flower.

Dendrobiuna Victoriae Reginae, a third member of the section, is the "blue" orchid of the Philippines. This orchid is endemic to the mountains above five thousand feet elevation and most of the plants which are collected come from Mount Santo Tomas near Baguio, one of the highest mountains in that area (7,500 feet elevation). The flowers of this species are not as large as the two previously discussed and the branched stems are narrower than the other two, being only eighteen to twenty-four inches long. The stems of the plant exhibit prominent nodes and internodes, as well as restricted joints. Flowering time is during July and August. At this time the plants have a few leaves near the end of the stems and the flowers develop in clusters of four to six from the nodes. The blossoms, which are about 11/2 inches across the petals, are rather shiny, sepals and petals similar, and the labellum is ovate and pointed. The outer half of the sepals and petals is blue or blue-purple iii color, which streaks inward to the whitish center of the flower. The flowers are quite longlasting and in their native habitat remain on the plants for from ten to fifteen days. The species was originally described by Loher in 1897, and is dedicated to Queen Victoria in commemoration of the Victorian Jubilee.

Probably, the next most important sub-genus, as represented by indigenous Dendrobiums, is that which includes three white flowered species, the section OXYGENANTHE. Of these three species, D. Sanderae is native to the Mountain Province of Luzon, while the other two, D. Schuetzi and D. Dearei, are collected from the northeast area of Mindanao near Surigao. All three are generally described as possessing thickened elongated canelike stems with prominent nodes, distichous leathery leaves and white flowers in short showy racemes.

D. Sanderae is native to the mountains of northern Luzon, where it grows at elevations greater than four thousand feet. At present, two plants which differ to a great extent in the size of the flower are delegated to this species. As presently understood, the plant with the large flowers is recognized as the typical species and is sometimes called D. Sanderae var. major. The smaller-flowered plant, with flowers about 1 1/2 inches across, is known as D. Sanderae var. parvifloruna. Both plants are frequently confused by native collectors and often the name D. Sanderae is applied to the smaller type.

The flowers of D. Sanderae (D. Sanderae var. major) are about three to 3 1/2 inches across and appear during April. It is a free-blooming species when grown in conditions comparable to the mountain atmosphere and is, indeed, one of the finest white Dendrobiums. Of the two types, this is the rarest. The smaller, D. Sanderae var. parvi florum, flowers from July to December and has a much darker throat which is colored with purple lines. Mature plants of both types are freeblooming and often support several clusters of six to twelve flowers. The species is named in honor of the English Orchid Company of Sanders.

D. Dearei is similar to the above member of the subsection with stoutish stems ten to fifteen inches long, distichously arranged leaves 1 1/2 to 2 1/2 inches long and lateral or terminal racemes that are produced at the summit of the plant. Seven to fifteen white flowers develop on a single inflorescence, and they all open at approximately the same time. The flowers are about two inches across and are quite similar to D. Sunderae, except that the throat is colored greenish.

The main flowering season for this species starts about July. However, on occasions the plants will flower at other months and sometimes more frequently than once a year.

This plant was discovered in 1882 by Colonel Deare for whom it is named, and is native to the Surigao and Dinagat area in Mindanao. The plant is quite hardy and ships very well.

The most recent addition to this remarkable group of white Dendrobiums is D. Schnetzci, which was first described by Rolfe in 1911. The plants of this species arc similar to the other two members, but the erect stout stems aj,c shorter, only twelve inches long, and are unusually narrow at the base. The short racemes are also lateral or terminal and have four to six white odorless flowers, each three inches wide. These open about September and last for three to six weeks in perfection.

These three Dendrobiums differ in the following distinctive features: The plants of D. Sanderae are the largest and most massive, while D. Dear•ci is somewhat smaller and D. Schuetzei is much smaller. The flowers of the large type of D. Sanderae and of D. Schuetzei are the largest and D. Dearei and the small type of D. Sanderae are much smaller. The flowers of D, Sanderae are colored with purple lines in the throat, while D. Schuetzei and D. Dearei have greenish coloration.

A more recent introduction as a cultivated species is D. Lyonii, a beautifully carmine or burgundy colored species from the low altitude forests of one thousand to five thousand feet elevation of Bataan and the Sierra Madre Mountains of eastern Luzon. This species was first described in 1907 as D, acuminatum, but later it was regarded as a distinct species and dedicated to W. S. Lyon, an ardent orchid fancier of Manila at that time. It is a member of the sub-genus SARCOPODIUM, a group that is closely related to the genus Bulbophyllum.

This species is recognized by its large, squat, ovoid, fourangled pseudo-bulbs, that are shiny light greenish-yellow in color. These have a papery sheath about their base and are terminated by a pair of oblng, elliptical rigid leathery leaves. The florescence is a beautiful arching raceme of ten to fifteen carmine colored starlike flowers. The scape is about ten to twenty inches long and each flower is from 2 1/2 to three inches across. Sepals and petals are lance-shaped, similar, and whitish with greenish-yellow tips and maroon red bases. The tip of the labellum is slender, pointed and whitish, while the base and lateral lobes are maroon-red. This is one of the most beautiful of the native Dendrobiums and has been collected by the author from Sierra Madre Mountains, 45 miles east of Manila.

The sub-genus CERATOBIUM, a group of orchids often called the "antelope Dendrobiums" because of their twisted petals, is represented by D. taurinuna, a species endemic to the Philippines. This plant is a strong growing one with erect stout stem which sometimes attains a height of five to six feet. The leaves are leathery, broad, and elliptical with an unequal apex bi-lobe. The florescence develops from the nodes of the leaves and is often two to four feet long. The fifteen to thirty flowers are spaced along the end of the raceme and are two to 2 1/2 inches across. Individual blossoms resemble the head of a bull, which imparts the specific name taurinum from taurus, "the bull." The twisted petals, which resemble the horns, are crimson magenta, and the sepals a lighter shade. The labellum is relatively massive, resembling the jaw of the bull and is purplish violet in color.

This species is collected from eastern Luzon in the vicinity of Tayabas and from the island of Mindanao. It flowers usually twice a year; during the early month of January and then later in September or October. The flowers are long lasting and remain in good condition for several weeks, opening a few at a time, thereby producing a display which will last about four weeks. Because the plant comes from an area of high annual precipitation, distributed quite evenly throughout the year, similar environment should be provided for in cultivation.

The section DESMOTRICHUM is one which includes quite a few botanicals of which two species are worthy of attention, because of their peculiar labellum. The plants of this section are distinguished by their thin stems that have a marked tendency to branch and are terminated by pseado-bulbs. The pseudo-bulb has a single terminal leaf at the base of which the flower develops. Generally, the flowers are of a fugacious nature, lasting only a day. Both of the representative species, D. scopa and D. plicatile, are found on Luzon in the Provinces of Laguna, Tayabas, and Rizal.

Dendrobium scopa is a plant with unusual flowers, its most outstanding characteristic being its deeply fringed lip. The branching stems of D. scopa are often ten to fifteen inches long with a flattened furrowed pseudo-bulb that is three inches long and half an inch wide. The stem and pseudobulb are yellowish-green and topped by a single leathery ovate, obtuse leaf about five inches long and three inches wide. The leaves which form on secondary and tertiary branches are smaller. The three to ten flowers which arise in terminal umbels of the leaf are white, scented like Dandelion flowers and open in the morning, only to close early in the afternoon. The sepals and petals are white, linear, lanceolate and the lateral sepal forms a short mentum. Petals are slightly shorter than sepals, while the lip has two triangular side lobes and a half. inch long middle lobe with numerous half-inch long fringes surrounding its apex. The short persistent papery bracts last long after the flowers have faded and fallen off.

This is quite a common species, blooming several times a year, especially about the middle of March through April. It is found in Tarlac, Rizal, Laguna, Mindoro, Leyte, Formosa,Celebes, New Guinea, and Samoa, and grows as an epiphyte at sea level up to fifteen hundred feet altitude. It can be easily established on a branch of wood or in a wooden basket for cultivation. The specific name scopa probably refers to the ~ ringed labellum of the species.

D.plicatile, the second member of the sub-section DESMOTHRICHUM, has deep yellow green, glossy pseudo-bulbs with slight ridges and furrows which are not so sharply defined as in the previously discussed species. The leaves are roundish and very coarse and the single flower of this species is axillary, ;hat is, it develops from the axil of the leaf. This flower is whitish and the petals and sepals are similar. It is the yellowish labellum of the flower which attracts attention to this plant. This is three-lobed, with a middle one that is frilled and somewhat folded in plaits, a characteristic which accounts for its specific name, plicatile. There is a variety of this species, D. plicatile var. convocarii, which is similar to the type differing only in having violet carmine spots on the petals, sepals and labellum.

Both D.scopa pa and D. plicatile are native to an area which experiences dry and wet seasonal conditions which should be duplicated if the plants are to be successfully cultivated.

D.crumenatum is one of the most widely distributed species of the genus Dendrobium and is indigenous to a large area of the Asiatic-Pacific. This species is a member of the section RHOPALANTHE, which is distinguished by a pseudobulbous thickening of the basal node of the otherwise slender stem.