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(Last Modified On 11/11/2012)
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(Last Modified On 11/16/2012)
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Genus
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PLEUROTHALLIS R. Br.
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PlaceOfPublication
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Aiton, Hort. Kew. ed. 2, 5:211. 1813
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Reference
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Lindl. Folia Orch. Pleuroth. 1859.
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Synonym
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Restrepia HBK. Nov. Gen. & Sp. P1. 1:366, t. 94. 1816. Kraenzlinella 0. KtZe. in Post & KuntZe, Gen. Phan. 310. 1904. Platystele Schltr. in Fedde Rep. Sp. Nov. 8:565. 1910.
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Description
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Small to medium-sized epiphytic herbs with caespitose or repent primary stems. Inflorescence terminal or rarely pseudo-radical. Sepals subequal, erect or spread- ing; dorsal sepal free or connate with the lateral sepals for a short distance, apex sometimes clavellate; lateral sepals from nearly free to connate to their tips, often gibbous at the base. Petals usually shorter and narrower than the sepals, apices plain or clavellate. Lip simple or three-lobed, shorter or about as long as, or some- times longer than, the petals, often unguiculate. Column about as long or shorter than the lip, winged or wingless, produced into a foot, or sometimes footless at the base; column-foot, when present, from short to as long as the column. Anther terminal, operculate; pollinia 2 or 4, ceraceous.
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Note
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Pleurothallis is one of the largest of the New World genera of orchids with many diverse forms. The division of the genus most often used is that which was proposed by Pfitzer (in Engl. & Prantl, Nat. Pflanzenfam., Nachtriage zu Teil II -IV: 105. 1897), but that is wholly artificial and quite impossible to use. The separations used here are quite as artificial as those of Pfitzer and have nothing to recommend them except, as far as the Panamanian species are concerned, they are convenient even though they are not absolute. Further, it may cause allied species to be widely separated.
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Key
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a. Apices of the dorsal sepals or of the petals not clavellate.
b. Sheaths not appressed to the stems, ciliate at their mouths....Series I. LEPANTHIFORMES (p. 86)
bb. Sheaths usually appressed to the stems, their mouths always glabrous.
c. Inflorescence exceeded by the subtending leaf, 1-flowered, fascicled or racemose ................. Series II. BRACHYSTACHEAE (p. 86)
cc. Inflorescence subequal to or exceeding the subtending leaf, 1- flowered, a fascicle on a long peduncle, or racemose ...... Series III. ELONGATAE (p. 87)
aa. Apices of the dorsal sepals and of the petals clavellate .......... Series IV. RESTREPIAE (p., 88)
Series I. LEPANTHIFORMES.-A small, rather natural group of species which are easily distinguished by the loose ciliate sheaths; inflorescence either longer or shorter than the subtending leaf.
a. Petals not ciliate nor ciliate-lacerate toward the apex; stems with 1-3 leaves.......................................................................... 1. P. BROADWAYI
aa. Petals ciliate or ciliate-lacerate toward the apex.
b. Sepals glandular-pubescent dorsally....................................... 2. P. GNOMONIFERA
bb. Sepals glabrous and smooth dorsally.
c. Leaves narrowly elliptic to oval, margins not recurved .................... 3. P. BLAISDELLII
cc. Leaves broadly oval to suborbicular-ovate, sphacelate margins prominently recurved............................................................................ 4. P. ROTUNDATA
Series II. BRACHYSTACHEAE.-An artificial group which probably has no phylogenetic value but is of value in separating and keying species of this difficult genus. Plants in which the inflorescence is exceeded by the subtending leaf. Inflorescence a single flower, a fascicle of flowers, a raceme -or fascicle of racemes.
a. Inflorescence a fascicle of one to many flowers at the apex of the secondary stem.
b. Leaves distinctly cordate at the base, mostly broad.
c. Lip about 6 mm. long; petals 2- to 3-nerved; flowers relatively large ................5. P. CARDIOCHILA
cc. Lip 4 mm. or less long; petals 1-nerved; flowers relatively small.
d. Petals ciliate or denticulate.
e. Base of the lamina of the lip with a transverse E-shaped callus .........................6. P. RHODOGLOSSA
ee. Base of the lamina of the lip without an E-shaped callus.
f. Lip triangular or triangular-subquadrate; disc smooth ........ 7. P. TRIANGULABIA
ff. Lip cordate to oblong-cordate; disc verrucose ........................ 8. P. ANTONENSIS
dd. Petals neither ciliate nor denticulate.
e. Base of the lip with linear-lanceolate arms; petals semi-terete above........................9. P. ARIETINA
ee. Base of the lip without lateral arms; petals not semi-terete. f. Base of lamina of the lip with a transverse E-shaped callus......................................................................... 6. P. RHODOGLOSSA
ff. Base of the lamina of the lip without a transverse E-shaped callus ................... I0. P. HOMOLANTHA
bb. Leaves not distinctly cordate at the base, usually attenuated.
c. Secondary stems winged .................................................... 25. P. ALPINA
cc. Secondary stems not winged.
d. Lateral sepals free at least above the middle, usually nearly to their bases.
e. Ovary echinate .............................................................................. 20. P. TRIBULOIDES
ee. Ovary not echinate. f. Petals abruptly dilated at the base ....................... 15. P. TRACHYCHLAMYS
ff. Petals not abruptly dilated at the base.
g. Lip simple........................................................................ ....... 18. P. OCTOMERIAE
gg. Lip with small falcate lateral lobes above the base .......... 19. P. UNCINATA
dd. Lateral sepals connate to their apices or nearly so.
e. Lip deeply saccate-concave ...................................... 12. P. CONCAVIFLORA
ee. Lip not saccate-concave.
f. Petals serrulate (or ciliate).
g. Dorsal sepal suborbicular; lip not Stelis-like ...................... 13. P. COBRAEFORMIS
gg. Dorsal sepal lanceolate; lip Stelis-like ................................. 11. P. SIMULANS
ff. Petals entire (sometimes ciliolate).
g. Sepals forming a distinct tube at the base, hispidulous dorsally .............................. 21. P. HISPIDA
gg. Sepals not forming a distinct tube at the base, the dorsal free from the laterals, glabrous.
h. Ovaries echinate ......................................... 20. P. TRIBULOIDES
hh. Ovaries not echinate. i. Lip about as broad as long, with large basal lobes ...... 14. P. ALLENII
ii. Lip longer than broad, simple or at least not with large basal lobes.
j. Pedicels of the flowers less than I/4 as long as the leaves ................................ 17. P. RUSCIFOLIA
jj. Pedicels of the flowers at least half as long as the leaves ...........................6. P. EUMECOCAULON
aa. Inflorescence a few- to several-flowered raceme.
b. Secondary stems less than half as long as the leaves they bear.
c. Sepals pubscent within ........................................................... 46. P. SEGOVIENSIS
cc. Sepals glabrous within.
d. Inflorescence a fascicle of short racemes, much shorter than the subtending leaf 36. P. STENOSTACHYA
dd. Inflorescence a single raceme nearly as long as the subtending leaf ..........37. P. OVATILABIA
bb. Secondary stems at least half as long as the leaves that they bear.
c. Petals linear or linear-lanceolate, entire.
d. Lip lepidote-verrucose above .......... 28. P. LEPIDOTA
dd. Lip not lepidote-verrucose above ..................................................... 42. P. PRUINOSA
cc. Petals broader than linear or linear-lanceolate (or if not then serrulate), entire or serrulate.
d. Petals very strongly recurved-arcuate; denticulate .... ...... 33. P. ROWLEEI
dd. Petals not strongly recurved-arcuate; denticulate or entire.
e. Lip broader than long, transversely elliptic ............................... 34. P. PRAEGRANDIS
ee. Lip not broader than long nor transversely elliptic.
f. Lip with small lateral lobes near the middle.
g. Secondary stems with prominent wings. (cf. also P. VELATICAULIS)
h. Dorsal sepal 9-11 mm. long, elliptic-obovate............29. P. COGNIAUXIANA
hh. Dorsal sepal 6-6.5 mm. long, elliptic to oblong-oblanceolate..... 25. P. ALPINA
gg. Secondary stems wingless.
h. Petals denticulate, obovate .............................................. 30. P. VITTATA
hh. Petals not denticulate, oblong to oblong-oblanceolatie.... 31. P. VELATICAULIS
ff. Lip without lateral lobes near the middle.
g. Petals not serrulate.
h. Lip with erect auricles near the middle; petals oblong to oblong-oblanceolate . 31. P. VELATICAULIS
hh. Lip without erect auricles near the middle; petals oblong-obovate to subrhombic........... 32. P. GELIDA
gg. Petals serrulate at least in part.
h. Lateral sepals connate to their apices; petals elliptic to elliptic-lanceolate ....... . 35. P. ELLIPSOPHYLLA
hh. Lateral sepals free for at least their length; petals broader than elliptic or elliptic-lanceolate.
i. Petals oblong-oblanceolate .......... 27. P. VERECUNDA
ii. Petals subrhombic-obovate .......... 26. P. PTEROCAULIS
Series III. ELONGATAE.-A series of species not necessarily closely allied but having the elongated inflorescence in common. Plants in which the inflorescence exceeds the subtending leaves in length. Inflorescence a single-flowered to a many-flowered raceme or a fascicle of flowers on an elongated peduncle.
a. Inflorescence a 1- to several-flowered fascicle on a long peduncle.
b. Lateral lobes of the lip erect; lamina with a pair of parallel lamellate calluses near the middle ........................................................ 23. P. FULGENS
bb. Lateral lobes of the lip, if present, not erect; lamina without parallel lamellate calluses.
c. Peduncle puberulent......................................................... 24. P. GLANDULOSA
cc. Peduncle glabrous ........................................................ 22. P. BRIGHAMII
aa. Inflorescence a raceme.
b. Peduncle ancipitous and winged.
c. Apex of the lip obtuse or retuse ........................................................ 50. P. SPECTABILIS
cc. Apex of the lip acute ......................................................... 49. P. PFAVII
bb. Peduncle not ancipitous nor winged.
c. Lateral sepals free nearly to their bases, at least not connate to near the middle.
d. Ovary muricate ................................. 51. P. MURICATA
dd. Ovary not muricate.
e. Disc of the lip with 3 prominent longitudinal calluses ............. 48. P. DOLICHOPUS
ee. Disc of the lip without prominent longitudinal calluses.
f. Sepals 10 mm. or more long . ................................ 52. P. CRENATA
ff. Sepals 19 mm. or less long.
g. Petals fimbriate or lacerate-fimbriate ......................... 41. P. ARISTATA
gg. Petals not as above.
h. Lip narrowly oblong; lateral sepals acuminate .......... 39. P. CALYPTROSTELE
hh. Lip ovate; lateral sepals acute or obtuse ......................... 37. P. OVATILABIA
c. Lateral sepals connate to about the middle or usually to near their apices.
d. Secondary stems less than half as long as the leaves they bear.
e. Ovary echinate ................................................. 40. P. FUEGII var. ECHINATA
ee. Ovary not echinate.
f. Petals fimbriate or lacerate-fimbriate ...................................... 41. P. ARISTATA
ff. Petals not fimbriate nor lacerate-fimbriate.
g. Lip 3-lobed; sepals pubescent within .................................. 46. P. SEGOVIENSIS
gg. Lip simple; sepals glabrous within ....................................... 38. P. GROBYI
dd. Secondary stems at least half as long as the leaves they bear.
e. Petals linear or linear-lanceolate ........................................... 42. P. PRUINOSA
ee. Petals not linear nor linear-lanceolate, either lanceolate or oblong or broader.
f. Petals truncate ............ .. 43. P. MACRANTHA
ff. Petals acute to obtuse or rounded but not truncate.
g. Sepals pubescent within .............. 46. P. SEGOVIENSIS
gg. Sepals glabrous within.
h. Lateral sepals 5-9 mm. long.
i. Petals eiliptic-lanceolate to ovate-lanceolate, 6-8.5 mm. long ............ 47. P. GHIESBREGHTIANA
ii. Petals oblong-obovate to subrhombic, 2.5-3.5 mm. long ........................... 32. P. GELIDA
hh. Lateral sepals 12-25 mm. long.
i. Lip with erect basal auricles or lobes; petals verrucose at the apex ..... 44. P. TUERCKHEIMII
ii. Lip without basal auricles or lobes,; petals not verrucose at the apex ............ 45. P. POWELLII
Series IV. RESTREPIAE. A small, natural group of species mainly distinguished by the clavellate apices of the dorsal sepal and the petals. Sheaths of the secondary stems usually maculate.
a. Disc of the terminal part of the lip verrucose; inflorescence more than half as long as the leaves.
b. Pedicel with a short filamentose appendage on the anterior side, just below the ovary ......... 53. P. FILAMENTOSA
bb. Pedicel without an appendage ................................................... 54. P. SUBSERRATA
aa. Disc of the terminal part of the lip not verrucose; inflorescence less than half as long as the leaf ... 55. P. XANTHOPHTHALMA
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