Pleonotoma exserta A.H.Gentry
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Authority
Maguire, Bassett. 1978. The botany of the Guayana Highland--part X. Mem. New York Bot. Gard. 29: 1-288.
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Family
Bignoniaceae
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Scientific Name
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Description
Latin Diagnosis - Frutex scandens; ramuli tetragoni, sine consociebus glandularum in nodis inter pedoles. Folia 2-5-foliolata vel 2-3-ternata, interdum cirrho simplici, foliolis ellipticis vel ovads, acuds, basi rotundads, coriaceis, glabris vel lepidoto-punctads. Inflorescentiae axillares et terminales, racemosae, glabratae; calyx cupulatus, 5-denticulatus, glabratus, apice chiolatus; corolla alba, hypocrateriformis, tubo perangusto, 2-2.9 cm longo; stamina aequaha, thecis exsertis, vix divergentibus; ovarium hneare, dense lepidotum; discus patelliformis. Capsula linearis, vix lepidota; semina bialata, omnina brunneola.
Species Description - Vine, the branchlets acutely tetragonal, the angles ribbed, lepidote, otherwise glabrous, the nodes without interpetiolar glandular fields or pseudostipules. Leaves pinnately 2-5-foliolate to 2-3-ternate, the leaflets elliptic or ovate, acute to short-acuminate, the base rounded, 2.5-13 cm long, 1-5.2 cm wide, coriaceous, glabrous above and below except for scattered lepidote scales, the margins minutely and inconspicuously lepidote and minutely simple puberulous, the petiole 1.5-6.4 cm long. Inflorescence a short terminal or axillary raceme, minutely and inconspicuously puberulous, the pedicels 5-7 mm long. Flowers with the calyx cupular, subtruncate, 5-denticulate, 3-6 mm long, 3-4 mm wide, mostly glabrous, the margin subciliate, with plate-shaped glands below margin; corolla white to yellowish, tubular-salviform, 3-3.6 cm long, 0.3-0.4 cm wide, the tube 2-2.9 cm long, the lobes 0.8-1 cm long, outside glabrous in lower half and puberulous in upper half, inside puberulous on lobes and below level of stamen insertion, with plate-shaped glands at base of lobes outside; stamens subexserted, the anther thecae parahel, 3-4 mm long, the connective extended almost 1 mm, the filaments equal, ca 0.5 cm long, staminode 1-2 mm long, insertion 1.5-1.6 cm from base of corolla tube; pistil 1-1.5 cm long, the style puberulous, the ovary linear, 2-3 mm long, 0.6-0.8 mm wide, densely lepidote and very slighdy puberulous, the ovules 2-seriate in each locule; disc patehiform, 0.5 mm long, 1.5 mm wide. Capsule linear, compressed, 10-25 cm long, 0.9-1.1 cm wide, the midrib barely evident, very obscurely lepidote, with scattered dark-drying raised glandular areas, drying gray or brown; seeds thin, bialate, 0.6-0.8 cm long, 1.3-1.6 cm wide, the wings uniformly brown, indisdncdy demarcated from seed body.
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Discussion
Type. VENEZUELA. Amazonas: Road from San Fernando de Atabapo to Santa Barbara 12-40 km from San Fernando, open white sand savanna, 110 m alt; vine, flower cream, fruits green turning brown, 24 Mar 1974, Gentry et al 10865 (holotype MO 2241755, isotypes MO, VEN, addidonal duphcates distributed as P. echitidea). Pleonotoma exserta is intermediate, both geographicahy and morphologicahy, between P. pavettiflora Sandwith of Matto Grosso, Brazil and P. echitidea Sprague & Sandwith of Guyana and has no definitive character not shared with one or the other of these two species (Table III). Nevertheless the Venezuelan populadon seems sufficiendy disdnct for specific recognidon, although adequate material to assess intrapopuladonal variability of the three taxa is not available. The three species are cleariy geographical isolates from a common ancestral stock, and discovery of addidonal populadons in intervening areas could one day warrant their reduction to subspecific or varietal rank.
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Distribution
Distribution. Endemic to white sand savannas of Amazonas Territory, Venezuela. VENEZUELA. Amazonas: San Antonio, upper Orinoco, 130 m, Williams 15046 (F, MO); Cerro Moriche, Rio Ventuari, 150 m, Maguire et al 30980 (K, NY); Cerro Yapacana, alto Rio Negro, 150 m, Maguire & Wurdack34484 (K): Carretera San Carios-Solano, 1-4 km NE de San Carios, 100 m, Morillo et al 3907 (MO, VEN); 2-6 km SO de Solano, 100 m Morillo et al 3982 (MO, VEN); 12-15 km NE de San Carlos, 100 m, Morillo et al 4198 (MO, VEN
Venezuela South America|