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(Last Modified On 2/4/2013)
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(Last Modified On 2/4/2013)
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Genus
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ONCIDIUM Sw.
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PlaceOfPublication
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Vet. Akad. Nya Handl. Stockh. 21:239. 1800
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Reference
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Lindl. Folia Orch. Oncidium, (1). 1855; Benth. & Hook. Gen. Pl. 3:562. 1883.
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Synonym
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?Phadrosantlus Neck. Elem. 3:153. 1790. Cyrtochilum HBK. Nov. Gen. & Sp. 1:349. 1815. Cyrtochilos Spreng. Syst. Veg. 3:729. 1826. Coppensia Dum. in Mem. Acad. Brux. 9:10. 1835, in nota. Tolumnia Raf. Fl. Tellur. 2:101. 1836. Xeilyathum Raf. loc. cit. 62. 1836. Xaritonia Raf. loc. cit. 4:9. 1836. Psychopsis Raf. loc. cit. 40. 1836. Lophiaris Raf. loc. cit. 40. 1836. Olgasis Raf. loc. cit. 51. 1836. Palumbina Rchb. f. in Walp. Ann. 6:699. 1861. Papiliopsis E. Morr. in Belg. Hortic. 24:261. 1874. Baptistonia Barb. Rodr. Gen. & Sp. Orch. Nov. 1:95. 1877.
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Description
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Erect or pendulous, epiphytic or infrequently terrestrial herbs with short, foliaceous stems, most frequently thickened into conspicuous, more or less ancipitous, 1- to 2 (rarely more) -leaved pseudobulbs, the bases enveloped in several papery or foliaceous bracts, or less frequently with the pseudobulbs very short, rudimentary, cylindric, subconic, or complanate-cylindric, enveloped in several papery sheaths, or the plants rarely with many distichously equitant leaves and entirely without pseudobulbs. Leaves subcoriaceous, coriaceous or fleshy, equitant, flat, terete or triangular. Inflorescences usually 1 or 2 short or elongate, often flexuose, erect, arching or laxly pendulous, branching panicles, simple racemes, or 1-flowered scapes produced from the lateral bases of the pseudobulbs, or in the equitant-leaved species from the axils of the leaves. Flowers often large and conspicuous, usually yellow or brown. Sepals usually subequal, spreading or reflexed, free, or the laterals somewhat connate rarely nearly to the apex, the dorsal sepal rarely much longer and narrower than the laterals. Petals subequal to the dorsal sepal or sometimes larger. Lip usually 3-lobed, often pandurate, rarely nearly entire, the base shortly clawed or sessile and adnate to the base of the column, usually forming a right-angle with it, the lateral lobes porrect, spreading or reflexed, sometimes obsolete, the central portion of the lip usually with an isthmus, the mid-lobe spreading, usually very broad and transversely dilated, rarely narrow, often emarginate or bifid, the disk usually conspicuously cristate or tuberculate. Column usually short, stout, the lateral margins near the stigma with or without auriculate or petaloid projections, the clinandrium very short and truncate or ovate and obliquely erect, entire or with the apex shortly bidentate, the base footless or sometimes apparently with a short foot, rarely produced into a prominent, erect, horn-like process. Anther terminal, operculate, incumbent, strongly convex, semiglobose or cucullate, 1-celled, imperfectly or rarely 2-celled; pollinia 2, usually deeply sulcate, waxy.
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Note
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A very large, polymorphic genus of often attractive, usually epiphytic Ameri- can orchids ranging from Florida and Mexico to the West Indies and South America as far as Peru, Bolivia, and Brazil. Twenty-six species are thus far known from Panama.
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Key
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a. Plants without pseudobulbs, or the pseudobulbs rudimentary and inconspicuous. b. Leaves solitary, fleshy, from the apex of a very short subconic or subcylindric stem. Basal sheathing bracts papery. c. Leaves broadly lanceolate to elliptic-oblong ...................................... 6. 0. CARTHAGINENSE cc. Leaves terete. d. Lip more than twice as long as the lateral sepals. Basal callus occupying less than half of the total length of the isthmus. e. Flowers very small, the lip 1 cm. long or less, at the base with 2 separate and distinct keels ending in small tubercles on either side of the central boss ................................................ 9. 0. EBRACHIATUM ee. Flowers of moderate size, the lip 1 cm. long or more, at the base without keels or tubercles on either side of the prominent central boss ......................................................... 24. 0. STIPITATUM dd. Lip less than twice as long as the lateral sepals. Basal callus very prominent, occupying nearly all of the central isthmus ........ 25. 0. TERES bb. Leaves many, coriaceous or subcoriaceous, the conduplicate bases c. Plants dwarf, less than 10 cm. tall. d. Leaves not equitant, the conduplicate bases enveloping a small pseudobulb. Peduncles filiform, not conspicuously flattened at the apex .... 8. 0. CRISTA-GALLI dd. Leaves equitant, the plants entirely without pseudobulbs. Peduncles conspicuously flattened, particularly near the apex... 22. 0. PUSILLUM cc. Plants robust, more than 35 cm. tall. d. Base of the lip with prominent, well-developed lateral lobes 17. 0. OCHMATOCHILUM dd. Base of the lip without prominent, well-developed lateral lobes. 19. 0. PANDURIFORME aa. Plants with conspicuous pseudobulbs. b. Lip conspicuously exceeding the lateral sepals in length. c. Pseudobulbs suborbicular, about as broad as long. d. Pseudobulbs very distantly inserted on an elongate, slender, flexuose rhizome ........ 11. 0. GLOBULIFERUM dd. Pseudobulbs approximate on a short rhizome. e. Bracts enveloping the base of the pseudobulb foliaceous. f. Apex of the pseudobulb diphyllous ..... 15. 0. NEBULOSUM ff. Apex of the pseudobulb monophyllous. g. Apical leaf of the pseudobulb much reduced, conspicuously less than the bract blades in length . 8. 0. CRISTA-GALLI gg. Apical leaf of the pseudobulb about equal to the bract blades in length. h. Lip with a distinct rectangular isthmus . 16. 0. OBRYZATUM hh. Lip with a sharp median constriction, but without a distinct rectangular isthmus ... 7. 0. CHEIROPHORUM ee. Bracts enveloping the base of the pseudobulb not foliaceous . 1. 0. AMPLIATUM cc. Pseudobulbs elliptic-oblong to oblong-ovoid, usually more than twice as long as broad. d. Pseudobulbs monophyllous at the apex. Sepals about 5 mm. long 20. 0. PARVIFLORUM dd. Pseudobulbs 2- to 3-leaved at the apex. e. Inflorescences with both normal and abortive sterile flowers. 12. 0. HETERANTHUM ee. Inflorescences with only normal fertile flowers. f. Sepals obovate-spatulate, broadly obtuse or truncate 16. 0. OBRYZATUM ff. Sepals lanceolate to elliptic-lanceolate, acute to subacute. g. Isthmus broad, at least half the width of the mid-lobe. 5. 0. CABAGRAE gg. Isthmus narrow, usually less than I/4 the width of the mid-lobe ....... 13. 0. ISTHMI bb. Lip subequal to the lateral sepals or shorter. c. Lateral sepals connate nearly to the apex ................................ 26. O. WARSCEWICZII cc. Lateral sepals free, or only very shortly connate at the base. d. Dorsal sepal and petals elongate, linear-spatulate, very dissimilar to the broad lateral sepals. Flowers solitary, at the apex of an elongate scape ...... 14. 0. KRAMERIANUM dd. Sepals and petals more or less similar in shape. e. Floral bracts very large and conspicuous. f. Flowers more than 3 cm. in diameter, the mid-lobe of the lip subequal to the dorsal sepal in width...... 21. 0. POWELLIIff. Flowers less than 3 cm. in diameter, the mid-lobe of the lip conspicuously exceeding the dorsal sepal in width ..... 4. 0. BRACTEATUM ee. Floral bracts small or slender and inconspicuous. f. Leaves narrowly linear-ligular, acute or acuminate. Pseudobulbs usually 2- to 3-leaved at the apex. g. Lower portions of the foliaceous bracts not articulated, without a suture ......... 10. 0. ENSATUM gg. Lower portions of the foliaceous bracts articulated, with a distinct suture. h. Lip with a distinct isthmus, the callus with 2 crenulate or denticulate, lateral plates at the base 3. 0. BAUERI hh. Lip without a distinct isthmus, the callus surmounted by 4 divergent, crenulate keels 18. 0. PANAMENSE ff. Leaves broadly lanceolate, obtuse to subacute. Pseudobulbs usually monophyllous at the apex. g. Lip distinctly shorter than the lateral sepals. h. Mid-lobe of the lip about equaling the dorsal sepal in width. Apex of the callus with a broad transverse plate ................................... 21. 0. POWELLII hh. Mid-lobe of the lip conspicuously exceeding the dorsal sepal in width. Apex of the callus with 3 fleshy teeth ....... 23. 0. STENOTIS gg. Lip about equaling the lateral sepals, or somewhat longer. h. Pseudobulbs exceptionally thin and flattened, without prominent longitudinal ridges, the conduplicate bases of the foliaceous bracts thin and papery .... 2. 0. ANSIFERUM hh. Pseudobulbs not exceptionally thin and flattened, with prominent longitudinal ridges, the conduplicate bases of the foliaceous bracts coarsely fibrous ...... 3. 0. BAUERI
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