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Trees with milky juice in bark and leaves; trunk with deep grooves of limited length; young parts covered with a rusty tomentum. Leaves persistent, with schizogenous secretory cavities with resinous contents and lactifers, often with spicular cells. Inflorescences axillary, pedunculate spikes, rather short, generally simple, rarely with few and short branches, many flowered. Flowers hypogynous, small, subsessile, 2-5-fascicled along rachis, each flower subtended by a minute ovate caducous bract. Calyx cupuliform, 5(-6)-denticulate, small, persistent, not accrescent; petals (4-)5-6(-7), fleshy, connate in the lower half, lobes ovate oblong; stamens generally 10, sometimes 15 (5 episepalous and 10 epipetalous), filaments filiform, adnate to the basal parts of the petals, anthers subquadrate-suborbicular; ovary superior, hairy, (3-)4(-5)-locular below, 1-locular above, style very short, stigma shortly 3-5-lobed. Drupe with thin-fleshy exocarp, endocarp crustaceous, tuberculate outside, embryo minute in top of the copious endosperm, the latter containing amylum, but no fatty substances.


C and northern South America present
Monotypic, in C and northern South America.

Wood observation species

M. guianensis


Vessels diffuse, solitary (9-49%) and in radial multiples of 2-4, round, oval or angular, 14-42 per sq. mm, diameter 63-132 μm. Vessel-member length: 854-1365 μm. Perforations scalariform with 4-9 bars per perfora- tion. Intervascular pits alternate, predominantly angular, partly round or oval, 6-13 μm. Vessel-ray and vessel-parenchyma pits large and simple, forming a scalariform or reticulate pattern. Thin-walled tyloses frequently present.
Rays of Kribs' heterogeneous type I, uniseriate or with very short multise- riate central parts of 2-3 cells wide, 13-21 per mm, up to 2166 μm high. Perforated ray cells not observed.
Parenchyma rather scanty to fairly common, predominantly apotracheal,diffuse and in small aggregates, partly scanty paratracheal, in strands of 6-13 cells.
Ground tissue composed of very thick-walled libriform fibres, lumen 16-27 μm. Minutely bordered pits with slit-like apertures, mainly confined to the radial walls. Length: 1474-2355 μm.
Crystals solitary rhomboidal, infrequently fragmented, in chambered ray or axial parenchyma cells.