Pleurothallis triangulilabia C.Schweinf. 1937 SUBGENUS Pleurothallis SECTION Macrophyllae-Fasciculatae Lindl 1859

TYPE Drawing Photo by Franco Pupulin/Drawing by Schweinfurth and Harvard Papers in Botany Vol. 26, No. 1 2021, The Researchgate Website

Common Name The Trianglular Lip Pleurothallis

Flower Size .5" [1.25 cm]

Found in Costa Rica and Panama in secondary forests, as well as on scattered trees along pastures, in the premontane forest of the Cordillera Volcánica Central and Cordillera de Tilarán in constantly windy locations , with perennial intermittent rains and fogs at elevations around 1300 to 2400 meters as a small sized, cool to cold growing, caespitose epiphtye with terete, slender, yellowish green ramicaul with a basal tubular, short, truncate sheath and another longer, tubular, tightly adpressed, obtuse sheath below the middle and carrying a single, horizontal becoming subpendent with age, coriaceous, sessile, ovate, subaciuminate, deeply cordate below leaf with overlapping lobes that blooms at most any time of the year on a terete, slender peduncle .48" [1.2 cm] long, arising through an erect, green becoming papyraceous spathe.

"The relatively small plants, with stems mostly around 6 to 8" [15 to 20 cm] long, and the glabrous, flat flowers facing the leaf, with the dorsal sepal subequal in width to the synsepal, the petals elliptic-lanceolate, and the lip transversely rectangular, are diagnostic of the species. Pleurothallis triangulabia is superficially similar to P. phyllocardia, with which it shares the shape of the ovate, acute leaves, deeply cordate at the base, the erect spathe, and the mostly dark purple flower that faces the surface of the leaf. Vegetatively, however, plants of P. triangulabia are usually distinctly smaller, a habit that the plants maintain also in cultivation—with mature stems around 6 to 8" [15 to 20 cm] long (vs.12 to 13.2" [30–33 cm]) and leaves to 4" x 1.6" [10 × 4 cm] (vs. 4.8 x 2.8" [12 × 7 cm]). The flowers are proportionately rounder, flat (vs. reflexed), often flushed with purple on a greenish yellow background (vs. solid purple in P. phylllocardia), with the dorsal sepal broadly ovate-suborbicular (vs. narrowly ovate), subequal to the synsepal (vs. distinctly wider), the petals shorter, elliptic-lanceolate (vs. oblong), and the transversely rectangular lip that is wider than long (vs. longer than wide). Pleurothallis triangulabia has been traditionally treated as a synonym of P. phyllocardia (e.g., Pupulin, 2002; Luer, 2003; Bogarín et al., 2014; Kolanowska, 2014), which it superficially resembles, but the type specimen at AMES that we chose as the lectotype clearly shows the large synsepal, the elliptic-lanceolate and comparatively short petals, and the transversely rectangular lip that Schweinfurth described and illustrated on the type sheet. Our recent collections from the western end of the Cordillera Volcánica Central and the Cordillera de Tilarán in Costa Rica correspond well to Schweinfurth’s concept, and for this reason, we treat P. triangulabia here as a good species." Pupulin etal 2021


References W3 Tropicos, Kew Monocot list , IPNI ; The Orchids of Panama L.O. Williams & P Allen 1946; Harvard Papers in Botany Vol. 26, No. 1 2021, The Researchgate Website photo/drawing fide;