Dulacia
Description
Shrubs (occasionally scandent) or trees. Branches slender, often yellowish in dry state. Leaves short-petiolate. Inflorescences axillary simple or laxly composed racemes; pedicels short. Flowers heterostylous; calyx cupular, margin obtusely 5-lobed or truncate, narrowed towards the base and forming a hypanthium, much accrescent towards fructification and finally enveloping the fruit almost entirely; petals 6, slightly perigynous, connate more or less halfway, apex inflexed; fertile stamens 3, inserted at the sinus between 2 petals, filaments flat, adnate to the basal parts of the petals, usually hairy, anthers oblong; staminodes 6, epipetalous, spathulate, usually hairy below, in the upper half bifid and glabrous; ovary semi-inferior, 3-locular below, 1-locular above, style subcylindric, slender, stigma capitate, more or less 3-lobed. Fruit a pseudo-drupe, surrounded by the enlarged thin-fleshy calyx except the free umbonate apex, endosperm containing abundant fatty oil and fairly frequent starch grains, embryo in the apical part of the albumen, cotyledons ovate.
Distribution
Amazonian Colombia present, Guianas present, Neotropics present, SE Brazil present, Southern America: Bolivia (Bolivia present)
13 species in the neotropics (from Amazonian Colombia to Bolivia and SE Brazil); 3 species in the Guianas.
Citation
Engler 1872 – In: Mar- tius, Fl. Bras. 12: 22
Sleumer 1935 – In: Engler & Prantl, Nat. Pflanzenfam., ed. 2, 16b: 27
Vellozo 1831 – In: Atlas: t. 78
Poeppig 1841: Nov. Gen. Sp. Pl.: t. 239
Wood
Vessels diffuse, solitary (50-94%) and in radial multiples of 2-3, round, oval or angular, 13-67 per sq. mm, diameter 44-113 μm. Vessel-member length: 299-569 μm. Perforations simple. Intervascular pits alternate, round to polygonal, 3-5,Urn. 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. Thin-walled tyloses infrequently present. Vascular tracheids associated with vessels, infrequently present. Rays of Kribs' heterogeneous type II to III, predominantly uni-, bi, or tri- seriate, 6-9 per mm, up to 996 μm high. Perforated ray cells infrequently present.
Parenchyma fairly common to abundant, predominantly apotracheal, diffuse, in small aggregates or in uniseriate rows between the rays, in strands of 3-5 cells.
Ground tissue composed of medium to thick-walled fibre-tracheids, lumen 14-20 μm. Pits bordered, in both radial and tangential walls, dia- meter of borders 4-6 μm. Length: 914-1791 μm.
Silica bodies fairly common to abundant in ray cells, rarely observed in axial parenchyma cells, surface granular, predominantly one, occasio- nally two, per cell, diameter 10-30 μm, in some specimens not exceeding 15 μm.
Crystals solitary rhomboidal, very scanty, in chambered or non- chambered parenchyma cells, absent in some specimens.
Parenchyma fairly common to abundant, predominantly apotracheal, diffuse, in small aggregates or in uniseriate rows between the rays, in strands of 3-5 cells.
Ground tissue composed of medium to thick-walled fibre-tracheids, lumen 14-20 μm. Pits bordered, in both radial and tangential walls, dia- meter of borders 4-6 μm. Length: 914-1791 μm.
Silica bodies fairly common to abundant in ray cells, rarely observed in axial parenchyma cells, surface granular, predominantly one, occasio- nally two, per cell, diameter 10-30 μm, in some specimens not exceeding 15 μm.
Crystals solitary rhomboidal, very scanty, in chambered or non- chambered parenchyma cells, absent in some specimens.
Notes
Heterostyly in this genus occurs regularly. Most species have both dolichostylous and brachystylous forms, formerly kept apart as separate species. It is probable that the brachystylous form, with its less distinctly developed stigma, is generally functionally male, and only the dolichostylous form is bisexual.