Trichilia pallida Sw.
Meliaceae
Occasional, evergreen, subcanopy or understory tree (10-15 m) most notable for its attractive, dehiscent, ariled fruits. T. pallida is a mid-level, primary forest tree, found growing in the semi-shade of taller arboreal species.
Description: T. pallida has a small, cylindrical and straight trunk (usually 20 cm, though occasionally reaching 35cm in diameter). Larger boles are fluted near their bases, indented by shallow folds. A moderate number of thin and relatively short branches populate the bole’s upper half and form a narrow crown of moderate density. Trichilia bark is smooth, dark olive-green or brown in color, and it exfoliates in thin, papery strips. Leaves (30 by 15 cm) are imparipinnately compound and alternately arranged. In each, seven leaflets populate a petiole that is deeply grooved along its superior margin. Smooth, pale green and papery, the nearly spatulate leaflet blades have slowly tapering bases, rounded apices, and moderate drip tips. The terminal leaflet is unique in that it is not supported by a separate section of petiole: instead it shares a single point of attachment with the two blades that flank it. Causing the leaf to appearing unbalanced, the visual effect of this leaflet arrangement is unusual, readily recognizable, and identifying. Trichilia foliage often yellows before being shed, usually around the time of new leaf production (February to April). Then, the crowns of these trees become stunningly obvious, comprised of three, distinct and contrasting leaf colors: dark green, yellow, and translucent, pale green for mature, dying and new leaves, respectively.
Flowers grow in small (2 cm), dense panicles attached to the leaf axils. Each is unobtrusive, tiny (4 mm), and creme-colored, with corolla parts arranged in fours. Flowers are produced in most seasons, though their abundance varies markedly from year to year. The months of February and early March see the most flowering activity, though some trees consistently blossom as early as December. Fruits expand rapidly from the old flower calyxes, and while immature they remain cloaked in a dense covering of golden hairs. After about four or five months of growth, the ovoid, football shaped pods – now bare – reach full size (1 cm). Fading from pale green to light brown, they dehisce into three, thin-walled sections. Each then reveals a single, glossy-black seed (7 mm), half covered by a bright orange aril. Fruition in Trichilia is nearly annual in frequency (with only occasional seasons missed) and it occurs from late June through early September. The magnitude of the seed crop varies enormously from year to year and between individuals and it follows no easily-recognizable pattern. Seeds, falling to the ground during the peak of the wet season, germinate within a month of harvest.
Similar Species: Members of the genus Trichilia are many and they are widely distributed in Costa Rica. At least four Trichilia species are found in Manuel Antonio National Park alone. All members possess imparipinnately compound leaves; dehiscent, capsule-like fruits opening in three sections; and brightly ariled seeds designed to attract avian seed-dispersers. T. pallida, when sterile, is most easily distinguished from other Trichilias by its relatively small stature and by the unique shape and arrangement of its leaflets. The flowers of this species are so short-lived as to be quite useless for field identification purposes, but its fruits are present for a longer period. The tomentose state of these capsules during most stages of their development is a unique characteristic among Manuel Antonio Trichilias.
Natural History: T. pallida flowers are pollinated by insects and bees while its fruits are dispersed by aril-seeking avifauna and arboreal mammals.
Distribution: Solitary individuals are scattered thinly throughout Manuel Antonio National Park’s primary forest. Trichilia pallida ranges from Mexico to northern Argentina and Paraguay.
Trees of Costa Rica's Pacific Slope 
