Swartzia rotundata R.S.Cowan
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Authority
Maguire, Bassett, et al. 1953. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 8 (2): 87-160.
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Family
Fabaceae
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Scientific Name
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Description
Latin Diagnosis - Arbor parva, omnes partes superficie foliolorum superiore excepta densissime fulvo-ferrugineo-sericeae; folia 3-4-jugata, petiolis subteretibus, 2.5-3=5 cm. longis, rachibus 2.5-7.5 cm. longis, supra leviter canaliculatis et ad basim foliolorum brevisissime alatis, petiolulis 1-4 mm. longis, foliolis 4-9.5 cm. longis, 2.5-5.5 cm. latis, valde discoloribus, chartaceis vel tenuiter coriaceis, vulgo ovali-oblongis vel ovato-oblongis, ad basim rotundatis, ad apicem rotundatis, fere retusis, interdum obtusis solum vel raro minime elongatis, supra subplanis, glabris, subnitidis, siccitate saepe olivaceis, infra saepe fuscis, sparse appressopubescentibus, pilis minutis, facie inferiore venis primariis in 6-8 paribus prominulis; inflorescentiae fasciculatae in ramis defoliatis productae, 8-18 cm. longae, multiflorae, racemosae, pedunculis 2.5—5.5 cm. longis, bracteis persistentibus, triangularibus, 0.8 mm. longis, bracteolis nullis, pedicellis 7-10 mm. longis; alabastra matura ovoidea, ca. 6 mm. longa et 5 mm. diametro, calyce ca. 5 mm. longo, in partes 4 recurvatas fisso, lobis plus minusve ovatis, intus glabris, petalum orbiculatum, 1-1.2 cm. longum, 1 cm. latum, unguiculo 3 mm. longo, glabro; stamina numerosa, glabra, 4 robustiora maiora, staminum minorum filamentis ca. 6.5 mm. longis, filiformibus, antheris oblongis, 1.5 mm. longis, staminum maiorum filamentis 7-9.5 mm. longis, crassioribus, antheris oblongis, 2-3 mm. longis; stigma brevisissimum, glabrum, stylus sericeus, leviter falcatus, ca. 1.5 mm. longus, ovarium sericeum, elongatum, 4 mm. longum, ca. 1 mm. diametro, 8-ovulare, stipite 5 mm. longo, glabro, filiformi; fructus immaturus lineari-fusiformis, usque ad 6 cm. longus et 1 cm. latus, fusco-sericeus.
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Discussion
TYPE: tree 20 m. tall, inflorescence erect, petals yellow, pink within, La Urbana, Orinoco River, Venezuela, February 27, 1949, Bassett Maguire & Bassett Maguire, Jr. 28985; New York Botanical Garden. Paratype: with same data, Maguire & Magutre 28986.
The very strong affinities of this species with S. fugax Spruce ex Benth. are certainly obvious but there appear to be a number of significant differences. S. fugax is apparently known only from the type locality, Santarem in the province of Para, Brazil (paratype in Herbarium New York Botanical Garden). The important differences between these two species may be best shown in a table:
Number of leaflets S. fugax S. rotundata
5(-7) (7-)9
Rachis 2.5 cm. long, wingless 2.5-7.5 cm. long, short-winged at base of leaflets
Leaflet pubescence On both surfaces On lower surface only
Peduncle length 6-8 mm. 25-55 mm.
Length of inflorescence 5-7.5 cm. 8-18 cm.
Petal shape and size "narrowly ovate, ca. long as calyx" nearly transversely oblong, ca. twice oblong, ca. twice
The flowers of both species are extremely interesting, for they appear to be near to what must have been the primitive flower type in the genus. In three species of the genus the stamens are equal, in contrast to the strongly dimorphic androecium of most of the species. Equality of stamens may be interpreted as more primitive than the dimorphic condition. S. fugax and the new species occupy an intermediate position in this regard, for although the usual more massive stamens can still be distinguished by their much stouter filaments, there is not the sharp contrast between the larger and smaller stamens. In fact, in these two species there is almost a complete gradation in stamen length and anther size from the larger to the smaller.