Swietenia macrophylla King
Meliaceae
Caoba, Mahogany
Occasional canopy or subcanopy tree (20-25m) most frequently found in the dry tropical forests of Costa Rica’s northern Pacific Slope. Caoba stands out for the lush green crown it supports during the extended dry season (when many other trees are deciduous) and the dark-grained, highly sought-after wood the species is famous for.
Description: Mature Caoba trees have stout, regular trunks (70cm) that are covered in thick, plate-like, grey bark. Crowns are rounded and densely covered in dark-green foliage.
Caoba leaves (32 x 14cm) are paripinnate, compound and alternate, each leaf sporting around 10 leaflets. The leaflets themselves are paired, asymmetrical and falcate, with each leaflet curving away from its companion. All foliage is shed annually, near the start of the dry season in December. Remaining bare only briefly, new pink or red, translucent leaves begin to expand rapidly, giving the tree an eye-catching, pastel hue – particularly when back-lit. The tree then maintains this thick, fresh, dark green leaf cover during the hot, parched months of the dry season, providing welcoming shade when most other trees are bare.
Soon after the leaves are out, flowers (1cm) appear in axillary panicles. Each is dominated by five, cup-shaped pale green sepals surrounding a white, toothed, tubular corolla. The open end of the corolla is capped by the broad, circular stigma. The flowers emit a characteristic, sweet aroma that fills the air and can be detected at significant distances from the fertile tree. Flowering in Caoba occurs in late January or February.
Soon thereafter, fruits (14cm long by 8cm in diameter) begin to grow. They form as erect, brown, dehiscent capsules consisting of five valves, but take nearly a year to mature and are thus nearly always present in the crown. Drying out soon after the rains stop and the leaves fall, the valves warp, separate, and fall from the capsule, revealing about 30-40 reddish-brown, winged seeds. Dislodged by the wind, the seeds ride the air currents, spinning much as Maple seeds are known to do. Seeds are released from the capsules in December and January.
Similar Species: Caoba’s falcate, pinnate leaves are unique and identifying for this species. In addition, the presence of the large, brown seed capusles held upright in the crown most of the year makes Caoba trees unmistakable. Cedro (Cedrela mexicana) has similar bark and trunk structure, and is found in the same dry habitats as Caoba, but its leaves are imparipinnate land also much longer.
Natural History: Caoba flowers are pollinated by bees. Its seeds are wind dispersed. Timing here is critical, since the seeds are released at the start of the dry season which tends to be the windiest time of the year in Costa Rica’s dry tropical forest, helping ensure that they land far away from the parent tree. When the rains return in April or May, the seeds are already in place and able to germinate right away, maximizing the amount of time that the young seedings have to get established before the onset of the next dry season, to which many of them will succumb. The tree’s strategy to generate leaves during the dry season also helps reduce the chance of significant insect predation and fungal disease that could damage these vital, food-producing organs.
Uses: Caoba trees are widely planted in parks as ornamentals, due in part to their nearly evergreen nature and the shade they provide during long, hot summer days. The wood is prized for its color and fine grain, and has been used extensively in furniture making and construction.
Distribution: In Costa Rica, Caoba is found primarily in the dry tropical forest habitat typical of the northwest Pacific slope. The species ranges from Mexico to Bolivia and Brazil.
Images: Tree Tree2 Trunk Bark Leaves Leaves (new) Flowers Flowers2 Flowers3 Fruit Fruit&Seed
Trees of Costa Rica's Pacific Slope 
