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Guarea glabra Vahl, a canopy tree in the Meliaceae. Note the still-unfolding apex of the leaf. Un árbol del dosel. Note que el ápice de la hoja todavía se está desarrollando.

Description: In flower, Meliaceae are very distinctive: the anther filaments are fused at the base, unlike those of other Sapindales. Vegetatively, they can be difficult to identify. A character often used in the Amazon is the sweet smell of the bark slash (except for the garlicky Cedrela;Gentry 1993), but bark slashing is generally frowned on at biological reserves like La Selva. All of the genera here except for Trichilia are even-pinnate (i.e., with compound leaves lacking a terminal leaflet). Trichilia usually has alternate leaflets. Guarea is easy to distinguish. It is the only genus of even-pinnate trees in which the leaf has a terminal bud that produces new leaflets as the leaf ages. The terminal bud is usually visible through binoculars, and often the relative ages of the leaflets can be determined by the amount of epiphyllous lichens and liverworts on them. The leaflets of Guarea can be mistaken for simple opposite leaves—look for the axillary bud at the true leaf base.

Economic uses: Two of the most valuable Neotropical hardwoods come from trees in this family: Spanish cedar (cedro) is Cedrela odorata, and mahogany (caoba) comes from several Swietenia species (not found at La Selva).

Descripción: Las flores de las Meliaceas son muy distintivas: los filamentos de los estambres se unen cerca de la base, a diferencia de los de otras Sapindales. Vegetativamente, es difícil reconocer la familia. Una característica que se usa frecuentemente en amazonas es el olor dulce de la corteza cortada, pero en reservas biológicas como La Selva, usualmente se prohibe cortar la corteza de árboles para identificarlos. Aparte de Trichilia, todos los géneros aquí son paripinnados (es decir, con hojas pinnaticompuestas que carecen de un foliolo terminal). Trichilia usualmente tiene foliolos alternos. Guarea es fácil de reconocer. Es el único género de árboles con hojas paripinnadas que tiene una yema terminal en cada hoja, la cual produce foliolos nuevos indeterminadamente. Se puede ver la yema con binoculares, y muchas veces se puede estimar la edad relativa de las hojas observando el monto de líquenes y hepáticas que llevan en sus superficies. Los foliolos de Guarea se puede confundir con hojas simples y opuestas—hay que buscar la verdadera yema axilar.

Usos económicos: De este familia se obtiene dos maderas muy valiosas: cedro (Cedrela odorata) y caoba (unas especies de Swietenia, que no se encuentra en La Selva).

Gen./spp. at La Selva: 4/13: Carapa (1), Cedrela (1), Guarea (9), Trichilia (2).

FIELD MARKS – alternate, paripinnate or imparipinnate compound leaves.

Cedrela spp – paripinnate leaves with many leaflets, odor of garlic, important timber tree. The most common species, Cedrela odorata, is identified by the presence of domatia for mites on the underside of its leaves.

Cedrela odorata
Cedrela odorata

Guarea – paripinnate leaves with a terminal bud (meristem) at end of the rachis identifies the genus. The bud is indeterminate, meaning that it can continue to add new leaflets over time.

Paripinnate leaves of Guarea.
Close-up of Guarea showing thickened petiolules and fist-shaped terminal bud.

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