Nord. J. Bot. - Section of tropical taxonomy A revision of the genus niplark (Polygonaceae) John Brandbyge Brandbyge, J. 1986. A revision of the genus Piptaris (Polygonaceae). - Nord. J. Bot. 6: 545-570. Copenhagen. ISSN 0107-055X. The neotropical genus Triplaris Loefl. ex L. is revised. A total of 73 taxa had previ- ously been described. In the present revision 17 species, 1 subspecies, and 1 variety are recognized. A new combination Triplaris melaenodendron (Bertol.) Standl. & Steyenn. ssp. colombiana (Meisner) Brandbyge is made, and a new variety T. setosa Rusby var. woyfkowski Brandbyge is proposed. Keys based on both pistillate and staminate specimens are presented. 1. Brandbyge, Botanical Institute, Univ. of Aarhw, Nordlandsvej 68, D K-8240 Ris- skov, Denmark. cited in the literature. In most of these later homonyms Introduction the authors did nothing more than cite the Linnean epi- Several regional treatments of the genus Triplaris Loefl. thet and extend his description. ex L. (Standley 1936; Standley & Steyermark 1946; Jacquin (1763) described Triplaris pyramidalis. In Duke 1960), have pointed to the urgent need of a criti- 1827 Weigelt (in sched.) in his exsiccate of plants from cal revision of the genus. This fact and the author’s ex- Surinam described the genus Blochmannia, and on the citing, though painful experiences collecting these same printed label is the name Blochmannia weigeltiana plants in Ecuador initiated the work on this revision. Rchb. without a separate description. Chamisso (1833) Approximately 2000 herbarium specimens from the described three species: Triplaris brasiliana, T. caracas- following herbaria have been studied: AAU, B, BM, C, sana, and T. surinamensis. Bertoloni (1840) described F, G, GB, K, M, MA, MO, NY, P, QCA, PH, RB, S, Vellasquezia melaenodendron from Guatemala. Stand- UC, US, and W. Herbarium acronyms according to ley and Steyermark (1943) made the new combination Holmgren et al. (1981). Visits to K and BM helped to Triplaris melaenodendron. Meyer (1840) published the solve some of the problems with the typification of the descriptions of five new species proposed by Fischer and oldest described species. Meyer. Weddell (1849) described eight new species and presented a key to the fourteen species known to him. Meisner (1855) in Martius’ Flora Brasiliensis recognized Taxonomic history thirteen species, of which one was new. In de Candolles’ The genus Triplaris was established by Loefling, one of Prodromus (Meisner 1856) he published the only mono- Linnaeus’ best pupils who died in Venezuela in 1756. graph existing of the genus. In this he recognized twen- The name was published posthumously by Linnaeus tyfive species, of which one was new. Bentham in Ben- (Loefling 1758), but no species was described and no tham and Hooker (1880) gave a description of the genus specimen cited. Linnaeus (1759) described the genus and mentioned, that the about 25 species could prob- and gave the trivial epithet “americana” to the speci- ably be reduced to 10. The most important descriptions men, on which he based his description. The identity made later than 1850 are Rusby’s (1896, 1900, 1927) and typification of Triplaris americana L. remained a from Bolivia. In this century the genus has been treated mystery until it was elucidated by Dugand (1960). Sev- on a regional scale by Eyma (1634), in Flora of Suri- eral T. americana’s with different authors have been nam, Standley (1936), in Flora of Peru, Standley and 0 NORDIC JOURNAL OF BOTANY NORD J BOr 6: 545-570. TROP 128 Nord. J Bot. 6 (5) IY86 545 Steyermark (1946), in Flora of Guatemala, and Duke (1960), in Flora of Panama. The Colombian botanist A. Dugand seems to have been working intensively with Triplaris in a certain period to judge from his annotations on herbarium sheets from several institutions including NY, US, K, and BM. He published but two small papers (Dugand 1952,1960). Brandbyge (1984) published three new spe- cies. Triplaris is a rather uniform genus. The only attempt to subdivide it was made by Meisner (1855, 1856), who recognized two groups, Platypetal@ and Stenopetalce. Platypetalre consisted of species with inner perianth seg- ments free from the perianth tube and basally broad- ened, while Stenopetakz consisted of species with lan- ceolate to linear or subulate inner perianth segments ad- nate to the perianth tube and not basally broadened. My observations are consistent with Meisner’s subdivi- sion. The generic delimitation between Triplaris and Ruprechtia was discussed in detail by Brandbyge and 0llgaard (1984). The 73 names described till now have been reduced to seventeen species with one subspecies and one variety. Morphology Habit All species of Triplaris are fast growing, small to me- dium-sized or occasionally tall trees (Fig. 1). Small but- tresses have been observed in T. dugundii. A record of 2 m high buttresses in T. weigeltiana from Brazil needs Fig. 1. General habit of Triplaris exemplified by Triplaris wei- verification. The trunk is straight, slender and ramified geliiana on Rio Cuyabeno, Ecuador. in the upper third only, and the crown is pyramidal in shape. Vegetative reproduction by suckers occurs fre- quently. Trees, which have been cut, often regenerate diagnostic value, but as the stipules are known from a with many shoots from the stump. Like other species few species only, this character has not been used to dis- growing in riverine habitats T. weigeltiana has been ob- tinguish between species in the present study. The stip- served to regenerate from fallen trunks by sending up ules enclosing the inflorescences in the bud stage are vertical side branches, which quickly attain the size of usually smaller and more scarious than the stipules en- individual trees. In all species recognized in the present closing the leaves. study the hollow branches and twigs are inhabited by ants, presumably all belonging to the genus Pseudomyr- Inflorescences mex. However, in specimens of T. cumingiana from coastal Ecuador, no ants were observed. Triplaris is strictly dioecious. The inflorescences are ter- minal or axillary pleiothyrsi, which are big and very con- spicuous at the time of fruiting. Stipules The staminate flowers are sessile or subsessile, and so The stipules are deciduous, up to 32 cm long cylindrical the part-inflorescences appear spike-like. Each inflor- organs. In the young stage they are completely closed escence usually has a short flowerless main axis, from and enclosing the apical shoot, later they are fissured which branching originates in various ways. The inflor- down in the full length and shed, leaving only a ring-like escence is open i.e. not terminated by a flower. The scar on the twig. The structure of the stipules is not fun- part-inflorescences are dichasia, but monochasia (scor- damentally different from the intrapetiolar stipules of pioid cymes) are also found. The part-inflorescences are Ficus and Magnolia, so this term has been used in the 3-7 flowered and always subtended by a small and descriptions below. sometimes inconspicuous bract. The two bracteoles are The stipules are pilose to velutinous or strigose out- fused into an ovate, acuminate organ, which is split side and glabrous inside. The indumentum might have a down on the abaxial side at anthesis. This interpretation 546 Nord. J. Bot. 6 (5) 1986 of the bracteoles is in accordance with Gross (1913: fera, T. vestita, and T. cumingiana have been recorded 311). Duke (1960) used the term ochreola for the brac- from elevations higher than 1000 m. Most species are teole. restricted to wet and relatively open habitats like ri- The pistillate inflorescences are fundamentally built verside forests, gallery forests and in the Amazon re- like the staminate ones, but the part-inflorescences are gion, Varzea forests. Extra-Amazonian species like T. always 1-flowered. The flowers are short-pedicellate purdiei, T. caracassana, T. melaenodendron, and T. cu- and the pedicels are elongated during the development mingiana have been recorded from dry thickets and dry of the fruits. deciduous forest. All the species are pioneers of forest clearings, and they are important components in all stages of secondary successions. Flowers The differences between the staminate and pistillate Pollination flowers are very pronounced. The staminate flowers consist of two whorls of slightly unequal perianth seg- The only data available on pollination in Triplaris are ments. The 3 outer segments are ovate, obtuse and the 3 the observations of Bawa and Opler (1975). The inflor- inner lanceolate to linear-lanceolate. The basal half of escences were seen visited by bees of the subfamily Me- the segments is connate into an infundibular-campan- liponinae, a group of opportunistic flower visitors. date tube. The length of the staminate flowers ranges From the observations it was concluded that the flowers from 2 to 7 mm, with the shortest (2 to 3 mm) found in were insect pollinated. Both female and male flowers T. americana and T. dugandii, and the longest (7 mm) were reported to produce nectar. Duke (1960) indicated in T. longifolia. that Triplaris is wind pollinated by stating: “The genus, Apart from the size-difference just mentioned all size like so many dioecious amentiferous groups, is badly classes in between are found, so size as well as indumen- complicated by specific intergradations.” The fact that turn of the flowers are not useful taxonomically. The the male trees have many flowers per inflorescence, nine stamens ranges from 3 to 8.5 mm long, and the fila- which produce much pollen, and the fact that the trees ments are adnate to the tube in their basal half. The an- usually grow in rather open habitats with short distances thers are biloculur and introrse. The stamens are between the two sexes suggests that possibilities for slightly projecting beyond the perianth at anthesis.