Ptychopetalum
Description
Glabrous shrubs or trees. Flowers heterostylous, fragrant, arranged in short axillaryfew-flowered racemes; pedicels subtended by a caducous bracteole. Calyx small, 5(-6)-dentate or -lobed, not accrescent; petals (4-)5(-6), initially coherent, finally free, linear-oblong, concave, inflexed with their membranous crenulate margin, hairy within; stamens usually twice the number of petals, rarely fewer by abortion, the epipetalous ones shorter, their filaments adnate to the petals, the episepalous ones longer, their filaments almost free, anthers small, oblong; disc obscure; ovary free, 1-locular, with 2 or 3 anatropous pendent ovules, style rather short, slenderly columnar, stigma subcapitate, 3-lobed. Drupe with a thin pericarp and crustaceous endocarp; seed 1, endosperm copious, corrugate-sublobate, exclusively containing fatty substances, with a small embryo at its apex.
Distribution
Guianas present, tropical South America present, tropical W and C Africa present
4 species, 2 in tropical W and C Africa, and 2 in tropical South America, 1 of these in the Guianas.
Wood
Vessels diffuse, solitary (8-32%) and in radial multiples of 2-4, round to oval or slightly angular, 12-34 per sq. mm, diameter 45-101 μm. Vessel- member length: 515-900 μm. Perforations simple. Intervascular pits alternate, round to polygonal, 3-6 μm. Vessel-ray and vessel-parenchyma pits of two types: half-bordered diffuse to alternate (similar in shape and size to intervascular pits) and large and simple.
Vascular tracheids associated with vessel multiples, sometimes integrating with narrow vessel elements, common.
Rays of Kribs' heterogeneous type II to III, uni-seriate and with short hi- seriate central parts, 13-20 per mm, up to 924 μm high. Perforated ray cells infrequently present.
Parenchyma abundant, predominantly apotracheal, diffuse, in small aggregates or in narrow irregular bands, partly paratracheal, in strands of 7-10 cells.
Ground tissue composed of very thick-walled libriform fibres, lumen 16-24 μm. Minutely bordered pits with slit-like apertures mainly confined to the radial walls. Length: 1394-3058 μm.
Silica bodies irregular to globular, with a coarsely granular surface, fairly common to abundant in ray cells, predominantly one per cell, diameter varying from 10-30 μm.
Crystals solitary rhomboidal, fairly common in chambered axial parenchyma cells, infrequent to common in ray cells.
Vascular tracheids associated with vessel multiples, sometimes integrating with narrow vessel elements, common.
Rays of Kribs' heterogeneous type II to III, uni-seriate and with short hi- seriate central parts, 13-20 per mm, up to 924 μm high. Perforated ray cells infrequently present.
Parenchyma abundant, predominantly apotracheal, diffuse, in small aggregates or in narrow irregular bands, partly paratracheal, in strands of 7-10 cells.
Ground tissue composed of very thick-walled libriform fibres, lumen 16-24 μm. Minutely bordered pits with slit-like apertures mainly confined to the radial walls. Length: 1394-3058 μm.
Silica bodies irregular to globular, with a coarsely granular surface, fairly common to abundant in ray cells, predominantly one per cell, diameter varying from 10-30 μm.
Crystals solitary rhomboidal, fairly common in chambered axial parenchyma cells, infrequent to common in ray cells.