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Flora of the Venezuelan Guayana

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BIGNONIACEAE

28. PLEONOTOMA Miers, Proc. Roy. Hort. Soc. London 3: 184. 1863.

Lianas, the branchlets acutely tetragonal with detachable ribs, without interpetiolar glandular fields; pseudostipules foliaceous or absent. Leaves biternate or triternate or ternately bipinnate or tripinnate, the terminal pinna often replaced by a trifid tendril. Inflorescence an axillary or terminal raceme. Calyx cupular, truncate, usually minutely denticulate; corolla white to light yellow, narrowly campanulate-funnel-shaped, the tube glabrous or variously pubescent in upper part. Anthers glabrous, the thecae straight, divaricate. Ovary oblong, ± lepidote or puberulous; ovules 2-seriate in each locule; disk cupular-pulvinate. Fruit an elongate-linear to elongate-oblong compressed capsule, the valves parallel to the septum, ± smooth, drying blackish, the median vein inconspicuous. Seeds thin, 2-winged, the wings membranous, brown, poorly demarcated from seed body.

Costa Rica to Argentina; 14 species, 6 in Venezuela, all of these in the flora area.

Key to the Species of Pleonotoma

1. Inflorescence an open raceme, with adjacent pedicel pairs separated by 2.5-5 cm, narrowly paniculate with the lower pedicels forked and 2-flowered; fruit drying greenish yellow; branchlets usually subtetragonal ..... P. albiflora

1. Inflorescence strictly racemose, ± congested with adjacent pedicels sepa-rated by less than 1.5 cm; fruit drying whitish or blackish ..... 2

2(1). Corolla tubular; thecae parallel and subexserted; leaves glabrous (except the margins), thick-coriaceous ..... P. exserta

2. Corolla campanulate or funnel-shaped; thecae divaricate, included; leaves membranous to thin-coriaceous, pubescent or glabrous ..... 3

3(2). Leaves and branchlets with dendroid trichomes ..... P. dendrotricha

3. Leaves and branchlets glabrous or with simple trichomes ..... 4

4(3). Pseudostipules conspicuous, foliaceous; leaves highly divided ..... P. jasminifolia

4. Pseudostipules narrow and inconspicuous, not foliaceous; leaves 2- or 3-ternate or pinnately 2-ternate ..... 5

5(4). Calyx 3-4 mm long; fruit 8-10 mm wide ..... P. clematis

5. Calyx 5-9 mm long; fruit > 15 mm wide ..... P. variabilis

Pleonotoma albiflora (Salzm. ex A. DC.) A.H. Gentry, Ann. Missouri Bot. Gard. 63: 71. 1976. -Bignonia albiflora Salzm. ex A. DC., Prodr. 9: 167. 1845.

Liana. Moist nonflooded evergreen lowland forests, 100-200 m; Delta Amacuro (Serranía de Imataca), Amazonas (near Puerto Ayacucho). Guyana, Suriname, French Guiana, Brazil (northeastern Amazonia, Bahia, Espírito Santo).

Although the branchlets are not always sharply and evenly tetragonal as in the other Pleonotoma species, the petioles and petiolules are always sharply angular unlike Memora, with which it might otherwise be confused.

Pleonotoma clematis (H.B.K.) Miers, Proc. Roy. Hort. Soc. London 3: 184. 1863. -Bignonia clematis H.B.K., Nov. Gen. Sp. (quarto ed.) 3: 141. 1818 [1819].

Liana. Semideciduous or deciduous forests, 100-1100 m; central and northern Bolívar, northern Amazonas. Anzoátegui, Guárico, Miranda, Monagas, Sucre; Colombia (Vaupés), Guyana, Suriname, French Guiana, Brazil (Amapá, Amazonas, Roraima). Fig. 403.

Pleonotoma dendrotricha Sandwith, Mem. New York Bot. Gard. 10(1): 141. 1958.

Liana. Poor-soil, sandy forests, 100-1000 m; widespread in Amazonas. Colombia (Guainía), French Guiana, Peru, Brazil (Amazonas, Pará, RondŁnia). Fig. 406.

Pleonotoma exserta A.H. Gentry, Mem. New York Bot. Gard. 29. 281. 1978.

Liana or vine. White-sand savannas, 100-500 m; Bolívar (Icabarú), Amazonas (widespread). Adjacent Colombia and Brazil. Fig. 404.

The narrowly tubular, white, presumably moth-pollinated flowers are very distinctive among species of Pleonotoma in the flora area.

Pleonotoma jasminifolia (H.B.K.) Miers, Proc. Roy. Hort. Soc. London 3: 184. 1863. -Bignonia jasminifolia H.B.K., Nov. Gen. Sp. (quarto ed.) 3: 141. 1818 [1819].

Liana. Poor-soil, especially sandy, forests, forest edges, 100-200(-1200) m; Bolívar (Río Parguaza), Amazonas (widespread). Colombia (Vaupés, Vichada), Brazil (Amazonas, RondŁnia). Fig. 405.

Pleonotoma variabilis (Jacq.) Miers, Proc. Roy. Hort. Soc. London 3: 184. 1863. -Bignonia variabilis Jacq., Pl. Hort. Schoenb. 2: 45, t. 212. 1797.

Liana. Nonflooded evergreen lowland forests, 100-500 m; Bolívar (Lago Guri, Río Acanán basin, Río Cuyuní basin, Serranía de Imataca), Amazonas (scattered). Widespread elsewhere in northern Venezuela; Central America, Colombia, Trinidad-Tobago, Ecuador, Peru, Brazil (Pará), Bolivia. Fig. 402.

In the Amazonian area, Pleonotoma variabilis is not always clearly differentiated from P. dendrotricha, which differs only in the denser indumentum of mostly branched trichomes.

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Scientific Comments:
Paul Berry (peberry@facstaff.wisc.edu) or Kay Yatskievych (kay.yatskievych@mobot.org).

 
 
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