Poulsenia
Content
Description
Trees, monoecious, aculeate. Leaves alternate in spirals; stipules fully amplexicaul, free; blade entire, pinnately veined. Inflorescences in the leaf axils, pedunculate, (subinvolucrate-)bracteate. Staminate inflorescences capitate; flowers distinct; tepals 4, connate; stamens 4; pistillode absent. Pistillate inflorescences capitate to subdiscoid; flowers 2-ca. 15; perianth tubular, 4-lobed; ovary free; stigmas 2, filiform. Fruiting perianth enlarged, yellow; fruit free; seed large, without endosperm, cotyledons thick and equal.
Wood
Vessels diffuse, solitary (35-90%) and in. short radial multiples or irregular clusters of 2-4, round to slightly oval, 4-10 per sq. mm, diameter 105-210 μm. Vessel-member length: 670-695 μm. Perforations simple. Intervascular pits alternate, round and/or polygonal, 6-9 μm. Vessel-ray and vessel-parenchyma pits larger, more irregular-shaped, half-bordered, the borders reduced. Thin-walled tyloses sometimes present, but always scarce.
Rays uniseriate and 4-6-seriate, 3-5 per mm, up to 960-1400 μm high. Heterogeneous, composed of procumbent cells, except for the uniseriate margins of 1-2 rows of square and/or upright cells. Occasionally some sheath cells. Radial latex tubes common.
Parenchyma vasicentric-aliform with short wings, occasionally confluent. Strands of 2-8 cells. The parenchyma distribution is not very clear in the transverse sections, because the lumen diameter/ wall thickness ratio of the fibres is almost equal to that of the parenchyma cells.
Fibres non-septate, lumen 15-35 μm, walls 2-3 μm. Pits simple, small, restricted to the radial walls. Length: 1410-1415 μm. F/V ratio: 2.0-2.1.
Vitreous silica abundant in the fibres, and occasionally also in the axial parenchyma and vessels.
Rays uniseriate and 4-6-seriate, 3-5 per mm, up to 960-1400 μm high. Heterogeneous, composed of procumbent cells, except for the uniseriate margins of 1-2 rows of square and/or upright cells. Occasionally some sheath cells. Radial latex tubes common.
Parenchyma vasicentric-aliform with short wings, occasionally confluent. Strands of 2-8 cells. The parenchyma distribution is not very clear in the transverse sections, because the lumen diameter/ wall thickness ratio of the fibres is almost equal to that of the parenchyma cells.
Fibres non-septate, lumen 15-35 μm, walls 2-3 μm. Pits simple, small, restricted to the radial walls. Length: 1410-1415 μm. F/V ratio: 2.0-2.1.
Vitreous silica abundant in the fibres, and occasionally also in the axial parenchyma and vessels.
Notes
No material from the Guianas was available. The description is based on samples from Central America and Colombia (ter Welle et al., 1986B).
Until recently the genus was regarded as monotypic with P. armata (Miq.) Standl. extending from Bolivia to Mexico. Two sterile collections from French Guiana (Paul Isnard region, Citron) strongly sug- gest the existence of another species.