DENDROBIUM

Swartz.

Epiphytes ; stems elongate or pseudobulbous . Leaves never plaited. Flowers racemose, often large and handsome . Sepals subequal , lateral obliquely adnate to the foot the column , and forming with it a sac or mentum. Lip contracted at thebase, rarely clawed , adnate to and incumbent on the foot of the column, side lobes embracing the column or spreading or 0, terminal narrow or broad, flat , convex, concave or saccate, disk often lamellate. Column short. foot long or short , top angled or 2-toothed ; anther 2-celled ; pollinia 4, free, ovoid or oblong , compressed, closely collateral in pairs in each cell.-Species about 300, Tropical Asiatic , Australian nd Polynesian .

The following attempt to arrange the Indian species of this vast and very intricate genus into deginable groups is open to much criticism in detail. It has entailed many months of labour , and it must stand or fall according to the verdict of those who may use it .

Series I.

Sect.I. SARCOPODIUM.

Pseudobulbs short, crect, uninodal , seated singly on a stout creeping rhizome . Leaves2, terminal , opposite , coriaceous , flat, persisten t. Flowers solitary from between the leaves , oron a 1-few -fld . scape , large or medium-sized ; mentum short, rounded -Habit of Bulbophyllum ,sect. Sestochilus.

Sect. II. BOLBODIUM.

Pseudobulbs erect ,as in Sarcopodium, but more tufted , clavate and stipitate. Leaves 2, terminal , opposite , coriaceous , flat, persistent. Flowers solitary or few from between the leaves, medium-sized , white or pale ; mentum short oro elongate.

Sect. III CADETIA

Stem branched ,pendulous,branches forming chains of uninodal sessile or stipitate pseudobulbs . Leaf solitary , terminal , coriaceous ,flat, persistent. Flowers 1-2 from the base of the leaf ,medium -sized ,white or pale; mentum short or elongate.

Sect. IV. STACHYBIUM.

Stem tufted , forming a smallpolynodal pseudobulb, or more or less elongate , often compressed ,simple or branched. Leaves many, narrow, membranous , deciduous or persistant . Flowers solitary, or in slender terminal or terminal and lateral racemes , small or medium -sized , often a flat keel on the disk that terminates in truncate crenate callus on the midlobe. -Small species of this section resemble Eria, sect. Bryobium.

Sect. V. FROMOSAE.

Stem rather short , tufted ,leavy , usually suberect often with deciduous black on the sheaths. Flowers solitary or racemose, often large, white or ple buff with faint colouring on the lip ; mentum usually long and funnel-shaped , or conical, acute , straight or incurved (short in D. albo-sanguineum); midlobe of lip often fimbriate on the margin or disk.-Similary hairly sheaths occur in sect. Virgatae and in D. nutans and a few others .

Series II.

Inflorescence lateral on the stem or pseudobulb (terminal in some species of Aporum ).

Sect. VI. Aparum

. Stems tufted , compressed , leafy . Leaves shortly ensiform distichous ,sheaths equitant , imbricating , fleshy or coriaceous , nerveless , persistant . Flowers small ,white or yellowish with pink markings, shortly pedicelled , solitary or in bractenate heads or short racemes , sometimes appering racemose from occupying the leafless ends of te braches ; mentum stout, as long as or longer than the short broad lateral sepals.

Sect. VII. STRONGYLE.

Stem tufted , slender , often branched , terete . Leaves terete , subterete or persistent . Flowers small , white or pale , solitary or as if racemed on the leafless ends of the stem or branches ; mentum as in Aporum.-This section is not very well distinguished from the preeding and following.

Sect. VIII. VIRGATAE.

Stems tufted , elongate,slender , but hard, rigid and polished, simple or branched , leafy, often swollen above the base. Leaves distichous , long , linear (shorter and oblong in D. tuberiferum & crumenatum), persistent . Flowers small or medium -sized , white or yellow with often pink or green markings, solitary or few on a leaf-opposed tubercle, or appearing racemed on the leafless ends of the stem or branches; sheaths sometimes pubescent with black hairs ; mentum usually long , stout , incurved or urceolate, truncate or lobes short.

Sect.IX.BREVIFLORES

Stems tufted, long or short, terete or clavate , sparingly leafy . Leaves oblong or lanceolate , peristent or deciduous . Flowers few, small, in short racemes or heads , pink or yellow , often dingy ; mentum large, saccate; lip very short, deeply concave or urceolate, truncate or lobes short.

Sect .X. PHDILONIUM .

Stems tufted , long ,terete , simple ,stout or slender , erect or pendulous ,leafy. Leaves distinchous , oblong or lanceolate, coriaceous or submembranous , persistent or deciduous . Flowers medium -sized , pink or yellow , rarely white, in short leaf-opposed often dense-fld.secund racemes, or in corymbs or tufts, rarely solitary ; mentum stout and often very long , equalling or longer (often much )than the short triangular sepals; lip usually very long and narrow , clawed , with often a small lamella, callus or spur on the claw near the base . -D. sanguinolentum is perhaps better refferred to Sect . XII.

Sect. XI. DISTICHOPHYLLAE.

Stems tufted, elongate, stout or slender ,leafy throughout . Leaves short, uniform, distichous , bases imbricating , persistent , emarginate or 2-fld .Flowers small, usually white or yellow , solitary or in short leaf-opposed, racemes ; mentum stout , spur-like , as long as the lateral sepals or longer; lip short , broad , sides recurved.-Habit of Appendicula.

Sect . XII. EUDENDROBIUM .

Stems tufted , elongate , stout or slender , clavate or nodose in some species. Leaves various , distichous (terminal and solitary in D. aggregatum only), membranous or coriaceous , persistent or deciduous . Flowers usually large in lateral pairs, fascicles or racemes , very rarely solitary , highly coloured or white.-This section is best characterized by wanting the sum of the characters of any of the others. The species with narrow sepals , petals and a long mentum approach formosoe and Pedilonium.