Chaunochiton
Description
Glabrous, small to medium-sized trees. Flowers shortly-pedicellate, in axillary and/or (sub)terminalshortly-pedunculate corymb-like panicles, bracts small. Calyx cup-shaped, 5-dentate, small in anthesis, much enlarged towards fructification; petals 5, linear-elongate, cucullate-dilatate at apex, membranaceous, connate or coherent below, or free; stamens 5, filaments filiform, adnate to the petals at base, anthers subglobose; disc absent; ovary superior, oblongoid, 5-ribbed lengthwise, 2-locular at base, 1-locular at apex; style filiform, slightly shorter than the petals, stigma capitate, 5-lobed. Drupe globose or subovoid, usually with 5-10 longitudinal shallow ribs; fruit-calyx accrescent to a large circularpapery wing in the centre enveloping the base of the drupe only (in the Guianas), embryo in the top of the copious endosperm, which contains exclusively fatty substances, no starch.
Distribution
Amazonian Colombia present, Guianas present, Southern America: Venezuela (Venezuela present)
3 species in Amazonian Colombia, Venezuela, and Brazil; 1 of these in the Guianas.
Wood
Vessels diffuse or forming a faint oblique pattern, solitary (19-79%) and in radial multiples of 2-4, round to oval or slightly angular, 4-13 per sq. mm, diameter 101-192 μm. Vessel-member length: 319-620 μm. Perfora- tions simple. Intervascular pits alternate, round to polygonal, 6-10 μm. Vessel-ray and vessel-parenchyma pits of two types: half-bordered diffuse to alternate (similar in shape and size to inter-vessel pits) and large and simple. Thin-walled tyloses infrequently present. Vascular tracheids asso- ciated with vessel multiples, sometimes integrating with narrow vessel ele- ments, common.
Rays of Kribs' heterogeneous type II to III, 1-4 seriate, 6-10 per mm, up to 1346 μm high. Perforated ray cells infrequently present.
Parenchyma abundant, predominantly apotracheal, diffuse, in small aggregates or in uniseriate rows between the rays, partly paratracheal, in strands of 3-5 cells.
Ground tissue composed of very thick-walled libriform fibres, lumen to the radial walls. Length: 1394-3058 μm.
Crystals solitary rhomboidal or of irregular shapes, predominantly in chambered axial parenchyma cells, infrequently in ray cells, abundant to very scarce.
Rays of Kribs' heterogeneous type II to III, 1-4 seriate, 6-10 per mm, up to 1346 μm high. Perforated ray cells infrequently present.
Parenchyma abundant, predominantly apotracheal, diffuse, in small aggregates or in uniseriate rows between the rays, partly paratracheal, in strands of 3-5 cells.
Ground tissue composed of very thick-walled libriform fibres, lumen to the radial walls. Length: 1394-3058 μm.
Crystals solitary rhomboidal or of irregular shapes, predominantly in chambered axial parenchyma cells, infrequently in ray cells, abundant to very scarce.