Microchilus tridax (Rchb.f.) Ormerod 2002
Photos by © O Vargas and The Pl@ntnet Website
Drawing by © Stig Dalstrom and The Swiss Orchid Foundation at the Jany Renz Herbaria Website
LATE 
EARLY
Common Name The Three? Microchilus
Flower Size .08" [2 mm]
Found in Guatemala, Belize, Honduras and Puntarenas province of Costa Rica in tropical wet forests in marshy grounds at elevations of 50 to 1900 meters as a small to just medium sized, hot to cool growing terrestrial with a creeping then ascending rhizome giving rise to an erect stem enveloped completely by leaf sheaths carrying 3 to 7, in a rosette, dark green above, purple to light green and 3 veined beneath, convolute, elliptic-ovate, acute, slightly acuminate gradually narrowing below into the petiolate base leaves that blooms in the late spring and early summer on an erect, puberulent, terminal, to 8.8 to 10.8" [24 to 27 cm] long overall, provided with 3 to 4 somewhat flared, tubular, bracts, rachis to 6" [15 cm] long, successively laxly many flowered inflorescence with triangular-ovate, acuminate, sparswely glandular, shorter than the ovary floral bracts and carrying small flowers with glabrous sepals.
"Easily confused with Microchilus constrictus and Microchilus arietinus especially in form of the lip, subcuneate base of the epipchile with relatively long and narrow more or less falcate lobules. It is however, easily separable from both by the thickened nerves in the lower half of the hypochile, papillate and concave in the center. M tridax is additionally separated from M arietinus by the spur form which is longer, narrowly cylindrical and attenute towards the blunt apex." Szlachetko & Kolanowska 2017
Synonyms Erythrodes purpurea (Ames) Ames 1915; Erythrodes tridax (Rchb.f.) Ames 1922; Physurus purpureus Ames 1908; *Physurus tridax Rchb.f. 1866
References W3 Tropicos, Kew Monocot list , IPNI
Beitr. Orchid.-K. C. Amer.: 64 Rchb.f 1866 as Physurus tridax
Studies in the Family Orchidaceae Fascile 2: 259 Ames 1908 as Physurus purpureus;
Studies in the Family Orchidaceae Vol 3: 37 Ames 1908 drawing fide;
Studies in the family Orchidaceae Vol V: 28 Ames 1915 as Erythrodes purpurea
Studies in the family Orchidaceae Vol VII: 76 Ames 1922 as Erythrodes tridax;
Icones Plantarum Tropicarum Plate 1329 Atwood 1989 as Erythrodes purpureum drawing fide;
* Lindleyana 17: 223 Ormerod 2002
Manual De Plants De Costa Rica Vol III Hammel, Grayum, Herrera and Zamora 2003 as Erythrodes tridax;
Orchid Genera and Species in Guatemala Archila, Szlachchetko, Chiron, Lipinska, Mystkowska and Bertolini 2018;
Vanishing Beauty, Native Costa Rican Orchids Vol 2 Lacaena to Pteroglossa Pupulin 2020 photo fide
Materials to the Orchid Flora of Colombia Vol 1: 298 Szlachetko & Kolanowska 2017 drawing fide;
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