Monographs Details: Tryssophyton merumense Wurdack
Authority: Maguire, Bassett & Wurdack, John J. 1964. The botany of the Guayana Highland--Part V. Mem. New York Bot. Gard. 10: 1-278.
Family:Melastomataceae
Description:Latin Diagnosis - Herba simplicicaulis plus minusve glandulis rubris sessilibus praedita; caulis usque ad folia gracilis 5-12 cm. Folia ad caulis apicem vel rare etiam ad caulis medium 10-14-verticillata sessilia vel petiolis alatis 2-4.5 X 0.3-0.5 cm oblanceolata vel elliptico-lanceolata apice late acuta vel obtusa basi anguste acuta tenuiter membranacea, supra sparsissime strigulosa, subtus glabra, ad margines conspicue subremoteque ciliolato-serrulata inconspicue trinervata. Flores solitarii vel geminati glabri; pedunculus nuUns (in floribus solitariis) vel 1.5-2 cm longus; pedicelli 8-15 mm longi glabri apicem versus 4-alati ad basim bracteolati, bracteolis 0.5-1 mm longis subulatis mucronulatis. Hypanthium (ad torum) 2.1 X 2 mm leviter 8-costatum; calycis tubus 0.1 mm altus, lobis 1.1-1.3 mm longis subulato-triangularibus anguste acutis. Petala 11 X 6 mm asymmetrice elliptica apice abrupte acuta apiculataque. Filamenta 4.5 vel 3.3 mm longa; antherarum thecae 2.3 vel 1.6-1.7 X 0.5 mm apice vix (0.1 mm) rostratae et minute (0.1 mm diam) uniporosae, connectivo basi thecis coalito et ad 0.55-0.65 X 0.4 mm incrassato ventraliter 0.1 mm bilobulato dorsaliter truncato. Stylus 10 X 0.2 mm; stigma truncatum; ovarium ad anthesim ca. 1 mm altum apice in collum 0.4 mm altum et ad 0.2 mm 4-lobulatum (lobis truncatis) protractum. Fructus maturus ignotus.

Discussion:

Fig. 67, g-k.

Type. Petals 1/2 white with exposed bud surfaces deep pink, anthers yellow, fruiting pedicel translucent green suffused with pink, common on mossy logs in forest, Merume Mountain, Partang River, upper Mazaruni River basin, Pakaraima Mts., British Guiana, elev. 1140 m, 4 Jul 1960, Stephen S. Tillett, Carolyn L. Tillett, & Rufus Boyan 43988 (holotype US 2343844).

In vegetative habit, Tryssophyton is very distinct from all known Bertolonieae and Sonerileae. In Cogniaux' keys, the closest New World relative would be Bertolonia, the closest Old World one Sarcopyramus. In Brenan's synopsis of the African Sonerileae (Kew Bull. 85-89. 1953), apart from the habit, Tryssophyton seems to key to Gravesia or Cincinnobotrys; both genera have somewhat different stamens. Neither Bakhuizen van den Brink's treatment of Malaysian Melastomataceae (Rec. Trav. Bot. Neerl. 40. 1943-45) nor Li's revision of the Chinese genera (Jour. Arnold Arb. 25. 1944) offer any relationship clues. The longitudinally bicolored petals of Tryssophyton are like those of Macrocentrum pusillum Gl. and M. glandulosum Gl. I do not believe that great importance should be attached to the 4-celled ovary of Tryssophyton, since both paucity of material and difficulty of dissection have prevented accurate knowledge of the constancy of 3-celled ovaries in the New World Bertolonieae; m y own dissection notes on 31. pusillum and M. gracile Wurdack, as well as Dr. Gleason's dissection notes on M . fruticosum GL, indicate the occurrence of 2- or 4-celled ovaries. In any event, both the whorled leaves and Marcetia-like stamens set Tryssophyton apart from other Bertolonieae.