Hylenaea
Description
Lianas or small trees, glabrous throughout; branches opposite. Inflorescences axillary and/or terminal, often aggregated, paniculate-corymbose or pseudo-cymose, pedunculate, branchlets sometimes capillaceous; bracts and bracteoles imbricate, minute. Sepals 5; petals 5; disk thin-fleshy, erect, short-cylindric; stamens 3, erect or strongly reflexed, filaments ligulate, slightly broadened towards base, anthers very small, dehiscing by transverse, confluent clefts; ovary depressed globose-trigonous, locules 3, ovules 4-8 per locule, superposed, style fleshy, subulate, stigmas obscure. Fruits consisting of 3, free, divergent mericarps, attached to the swollen receptacle, convex, dehiscing along median suture, pericarp woody; seeds erect from the base, affixed by a basal wing of variable shape, embryoniferous part apical, thick, coriaceous.
Distribution
Guianas present, Neotropics present
3 species occur in the Neotropics, 2 of which occur in the Guianas.
Wood
Growth rings indistinct, indicated by a zone of radially flattened fibres and by the presence of more numerous crystals in the wide rays; unlignified cells obscure.
Vessels diffuse, solitary, 12-16 per sq. mm, roundish, of two different sizes, diameter narrow ones 20-40(60) μm, of the wide ones (80)100-200 μm. Vessel-member length: 775(630-960) μm. Perforations simple. Intervascular pits alternate, elongate, 3-4 μm, slits enclosed or confluent, resulting in striations. Vessel-ray pits as the intervascular pits.
Rays uni- and multiseriate, up to 22 cells(= 300 μm) wide, 6 per mm, of which 2-3 wide rays. Heterogeneous in both types, the wide rays with predominantly procumbent and square cells and short margins of square and upright cells, over 800 cells (= 12 mm) high. Rhombic crystals numerous in wide rays, with a concentration on the growth ring border.
Parenchyma scarce, vasicentric, one cell wide sheath. Strands of 6-12 cells.
Ground tissue of fibre-tracheids, septate and non-septate fibres intermingled. Fibre-tracheids lumen c. 12 μm, walls 3-4 μm, numerous small bordered pits on both radial and tangential walls. Septate and non-septate fibres with lumen of 18-20 μm, walls 3 μm. Pits simple on radial walls. Length fibre-tracheids: 1180(840-1500) μm, septate and non-septate fibres 800(670-900) μm. FIV ratio: 1.52.
Vessels diffuse, solitary, 12-16 per sq. mm, roundish, of two different sizes, diameter narrow ones 20-40(60) μm, of the wide ones (80)100-200 μm. Vessel-member length: 775(630-960) μm. Perforations simple. Intervascular pits alternate, elongate, 3-4 μm, slits enclosed or confluent, resulting in striations. Vessel-ray pits as the intervascular pits.
Rays uni- and multiseriate, up to 22 cells(= 300 μm) wide, 6 per mm, of which 2-3 wide rays. Heterogeneous in both types, the wide rays with predominantly procumbent and square cells and short margins of square and upright cells, over 800 cells (= 12 mm) high. Rhombic crystals numerous in wide rays, with a concentration on the growth ring border.
Parenchyma scarce, vasicentric, one cell wide sheath. Strands of 6-12 cells.
Ground tissue of fibre-tracheids, septate and non-septate fibres intermingled. Fibre-tracheids lumen c. 12 μm, walls 3-4 μm, numerous small bordered pits on both radial and tangential walls. Septate and non-septate fibres with lumen of 18-20 μm, walls 3 μm. Pits simple on radial walls. Length fibre-tracheids: 1180(840-1500) μm, septate and non-septate fibres 800(670-900) μm. FIV ratio: 1.52.