Ximenia
Description
Root-parasitic shrubs or low trees. Branches usually armed with axillary spines and/or ramal thorns. Leaves spiral, sometimes fascicled on brachyblasts. Inflorescences axillary, or at the end of a short lateral branch (which may turn into a thorn), rather few-flowered pedunculate, sometimes umbel-like cymes, or flowers in fascicles, rarely solitary. Calyx small, saucer-shaped, with (3-)4(-5) teeth or sepals, persistent, hardly or not accrescent in fruit; petals 4 (rarely 5), free, linear-oblong, upper half recurved, with a brush of hairs on the inner surface, caducous; stamens free, hypogynous, usually twice the number of petals, filaments filiform, anthers oblong-linear to subovate; disc absent; ovary superior, (3-)4-locular in the basal part, style more or less columnar, stigma capitate, small. Drupe with a rather thin pulpy pericarp, and a crustaceous to woody endocarp; endosperm copious, oily, embryo very small.
Distribution
Guianas present, tropics and subtropics present
8 species in the tropics and subtropics, of rather close affinity. 1 var. of X. americana in the Guianas.
Wood
Vessels diffuse, almost exclusively solitary (90-99%), rarely in radial multiples of 2, round to oval, 31-58 per sq. mm, diameter 54-84 μm. Vessel- member length: 150-340 μm. Perforations simple. Intervascular pits alternate, round to polygonal, 4-7 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. In cross fields with procumbent parenchyma-cells half-bordered pits and in cross fields with square or upright parenchyma-cells large and simple pits. Thin- walled tyloses infrequently present.
Rays of Kribs' heterogeneous type II to III, 1-3 seriate, 8-16 per mm, up to 235 μm high. Perforated ray cells infrequently present.
Parenchyma scanty to fairly common, predominantly apotracheal, dif- fuse or in small aggregates, partly scanty paratracheal, in strands of 3-4 cells.
Ground tissue composed of thinto medium thick-walled fibretracheids, lumen 13-16 μm. Pits bordered, in both radial and tangential walls, diameter of borders 5-6 μm. Length: 600-1193 μm.
Crystals solitary rhomboidal, absent or abundant, in chambered or non-chambered ray cells.
Rays of Kribs' heterogeneous type II to III, 1-3 seriate, 8-16 per mm, up to 235 μm high. Perforated ray cells infrequently present.
Parenchyma scanty to fairly common, predominantly apotracheal, dif- fuse or in small aggregates, partly scanty paratracheal, in strands of 3-4 cells.
Ground tissue composed of thinto medium thick-walled fibretracheids, lumen 13-16 μm. Pits bordered, in both radial and tangential walls, diameter of borders 5-6 μm. Length: 600-1193 μm.
Crystals solitary rhomboidal, absent or abundant, in chambered or non-chambered ray cells.