Psychotria irwinii Steyerm.
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Authority
Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
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Family
Rubiaceae
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Scientific Name
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Description
Latin Diagnosis - Arbor vel frutex 2-8-metralis, ramis glabris; stipulis ovatis lanceolato-oblongis vel oblongo-ovatis subacutis vel obtusiuscule acutis vel obtusis 6-10 × 4-5 mm extus glabris vel minute puberulentibus marginibus superioribus minute ciliolatis, ceteris mox deciduis, cicatrice stipulari basi annulo pilorum ferrugineorum fimbrillatorum manifeste munita; foliis oppositis petiolatis, petiolis 0.5-2.5 cm longis glabris; laminis coriaceis vel subcoriaceis in medio manifeste latioribus late obovatis elliptico-obovatis ovato-ellipticis vel late ovatis atque oblongo-ellipticis apice abrupte caudatis basi cuneatim longiacutis, acumine 1-2 cm longo, ubique glabris, 9-21.5 × 3.5-13.5 cm, nervis lateralibus utroque latere 6-8(-10) subtus conspicue elevatis supra impressis ante marginem 1-5 mm anastomosantibus, domatiis nullis; inflorescentia cymoso-paniculata subhemisphaerica vel late pyramidali 3.5-8.5 cm longa 5.5-9 cm lata, axibus 6-12 plerumque 3-verticillatis plerumque 2- vel 4-verticillatis sparse vel dense puberulentibus infimis 1-3.5 cm longis; bracteis suborbiculari-ovatis obtusis vel subacutis sub floris 0.5 mm longis sub axibus inflorescentiae 1 mm longis; floribus sessilibus vel pedicellatis, centralibus primum interdum sessilibus vel breviter pedicellatis, lateralibus semper pedicellatis, pedicellis 1.5-6 mm longis puberulentibus, interdum floribus omnibus pedicellatis; pedunculo 3.5-9 cm longo glabro vel puberulenti; calyce hypanthioque 2.5-4 mm longo puberulenti vel glabro, hypanthio 1.5-2 mm longo 2-2.5 mm lato subcampanulato plerumque minute puberulenti rarenter glabro; calyce 1.5-2 mm longo 2-3 mm lato margine repando-denticulato vel subtruncato-repando, tubo calycis intus basi sinubus oppositis 1-2-glandulis praedito, dentibus breviter lateque triangularibus 0.1-0.2 mm longis 0.5-1.5 mm latis marginibus minute cilio-latis; disco tubo calycis muito breviore; corolla infundibuliformi vel subcylindrico-infundibuliformi (9.5-) 10-11 mm longa extus glabra vel sparse papillata, tubo 6-6.5 mm longo basi 1.5-3 mm lato fauce 2.2-4.5 mm lato intus parte inferiori 3.5 mm glabro in medio sursum piloso, lobis ligulato-lanceolatis vel oblongo-lanceolatis 4-5 × 1-2 mm apice dorso carinatis incrassatis calcari cucullata subcorniculato instructis; staminibus plerumque exsertis, antheris oblongis 2-2.3 mm longis 0.9 mm latis, filamentis 3-3.5 mm longis; stylo infra medium puberulenti-papillata; bacca ovoidea vel oblongo-ovoidea 6-7.5 mm longo 5-7 mm lato valde obtusiuscule 10-costata, pyrenis facie ventrali planis secus longitudinem leviter 1-porcatis vel haud porcatis.
Distribution and Ecology - Distribution. Suriname, British Guiana, northeastern Venezuela, and Brazil.
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Discussion
Fig 66.
Type. Forested lower slopes, Wilhelmina Gebergte, 5 km east of confluence of Lucie and Oost Riviers, 3° 36'-3° 41' N, 56° 30'-56° 34' W, Suriname, alt 350 m, 13 Sep 1963, tree to 3 m high, 8 cm diam, flowers white, fruit orange, H. S. Irwin, G. T. Prance, T. R. Soderstrom & N. Holmgren 55706 (holotype NY, isotype VEN).
This taxon, named in honor of Dr. Howard Irwin, Executive Director of The New York Botanical Garden, is characterized by the large corollas with a relatively broad tube at the base and orifice, by the relatively much larger calyx and hypanthium, the prominent persistent and large fruiting calyx, the ciliolate stipular margins, and the disk deeply sunken within the calyx tube. There is variation in pubescence of stipules, calyx, and hypanthium, this pubescence more marked in Steyermark 86980. The calyx in this collection is more toothed than in most of the other collections cited. The seed is flat on the commissural face, and may lack any longitudinal ridge or in Maguire 40535 may show a slight longitudinal ridge running down most of the length.