This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(tree and life; they are epiphytic). Orchidaceae. Epiphytic orchids of great horticultural merit, grown in hothouses and greenhouses.
Pseudobulbs (stems), tufted or arising at intervals from a creeping stem sometimes very short and thick, more commonly elongated and often thickened at or near the base, naked or leafy at time of flowering: flowers usually showy, rarely small, in terminal or lateral racemes which are long and lax or short and dense, sometimes of a few flowers, or sometimes reduced to 1 or 2; sepals about equal, the dorsal free, the lateral adnate obliquely to the foot of the column, forming either a short sac-like or long spur-like foot or mentum; petals usually resembling the dorsal sepal, either broader or narrower; lip jointed or adnate to foot of column, 3-lobed or entire; pollinia 4. - A large genus of about 600 species, ranging from India and Ceylon to Austral., New Zeal., Japan, and the Pacific Isls., being especially numerous in the Malay Archipelago. There are numerous hybrids, artifically produced.
There are two well-marked sections in this genus for the guide of the cultivator, the evergreen and the deciduous. The first named should not be allowed to become dry at the roots at any period, or loss of vigor will result. Among these, also, are some that need warm-house treatment all the time, such as D. Phalsenop-sis, D. bigibbum, D. Bensonise, D. Brymerianum, D. Dearei, and others. There are, in fact, but few among the evergreen species that need a coolhouse, and of these D. formosum, D. infundibulum and its variety Jamesianum are conspicuous. Apart from these, the evergreen dendrobes should be kept in a warmhouse during winter where 60° F. may be maintained. - All the deciduous species (typified by D. Nobile, D. Wardianum and D. Pierardii) need a marked resting period, easily determined by the finishing up of the growth in autumn, and the swelling of the nodes for flowering in spring. When at rest, it does not hurt the plants to be subjected to a low temperature of 45°, and it may be done to retard plants for later blooming, allowing the day heat to be regulated by the sun, with plenty of ventilation on favorable days.
After the pseudobulbs have flowered, they cease to be of value to the plants, and should be cut out; if there are portions that have not produced flower-buds, these may be used for propagation, cutting the pieces into lengths of several joints or nodes, and laying them on moss in a warm propagating-house or -case, when they will soon produce growths. The above also applies to the hybrids, now so numerous, that have been raised from the deciduous Indian species. - Another section that requires warmth in winter, and now very much grown for cut bloom, is represented by D. Phalaenopsis and D. bigibbum. These are Australian, quite distinct in growth, and usually short-lived in cultivation. The flowers are produced freely for a few years, are very decorative, and the plants may be increased by taking off the young plants that often appear on the stems. These often can be grown on to strong flowering specimens, and thus the stock maintained. When wintered in a temperature less than 60°, the plants suffer, and great care is necessary at the time the young growths appear in spring to prevent damping off. Small pots or pans are best, and always keep the plants suspended near the sun and air.
The evergreen tropical species, as D. densi-florum, D. thyrsiflorum, D. aggregatum, D. Farmeri, D. moschatum, D. fimbriatum and D. Dalhousieanum, also need warmth in winter and must not be dried severely during the resting-period or loss of vigor will ensue at the price of blooming. This section of the genus produces flowers from the old stems for many years. It frequently happens that growths made in India will bloom long after the plants have become established in gardens. It is thus unwise to cut old growths unless they become withered or dead. Enough water may be given to keep the plants plump, and the flowers will be produced freely in their season. In some species, growth begins before or at the time of bloom. This is usually a sign of extra vigor and should not be discouraged. The proper time to repot with all plants of flowering age, is when they begin to recuperate in early summer after the bloom is past; young roots will be seen pushing out at the base of the stems, and if this is anticipated by a week or two, the new material is soon taken to by the roots and no check is experienced. Good sound osmundine is the best material, always using small receptacles rather than large, and if larger than a 6-inch pot or pan, use perforated ones.
The roots do not like exposure, but the material will be kept in a sweet healthy condition. Moss is best avoided in most cases; it often fails to grow, and is inimical to the welfare of the plants; when it does grow, it holds too much moisture about the roots. (E. O. Orpet.)
A. Leaves equitant.
Section I. Species 1 and 2.
Aa. Leaves not equitant. b. leafsheaths black-hairy.
Section II. Species 3-10.
bb. leaf - sheaths not black-hairy.
c. Pseudobulbs not thickened at base. d. Mentum or chin of flowers elongated.
Section III. Species 11-14.
dd. Mentum or chin of flowers short (rather long in D. ramosum). e. Flowers usually in pairs, rarely 1 or 3 or more. F. The pseudobulbs leafless at flowering time. .
Section IV. Species l5-44.
ff. The pseudobulbs leafy at flowering time
Section V. Species 45-55.
ee. Flowers in 3-to many-fid. racemes (single in D. Jenkinsii). f. The pseudobulbs 1-lvd., short, fusiform.
Section VI. Species 56 and 57.
ff. The pseudobulbs several-lvd. G. Racemes very short, glomerate.
Section VII. Species 58.
gg. Racemes usually long, not glomerate. H. Sepals and petals hairy externally; lateral lobes larger than middle lobe of lip.
Section VIII. Species 59.