proportions,
its expansive, often spherical crown, and its curiously shaped
seed pods. The abundance of this tree (especially in the province
of Guanacaste where it is prized for the shady relief it provides
from the intense sun) coupled with its immensity have made the
Guanacaste one of the most widely recognized and appreciated species
in Costa Rica - in fact, it is the national tree of this country.
Description: Guanacaste boles are cylindrical and generally straight and columnar, with mature specimens reaching well over one meter in diameter. Unusual in a tree of these proportions, buttresses are completely lacking. The bark is light gray in color and it is textured by prominent, dark, vertical fissures that show a marked reddish-brown color upon close inspection. In young trees, these fissures are closer together and their confluence lends a hallmark, reddish hue to the bark of Guanacaste saplings. Older specimens often present broken, chipped or scared bole surfaces. The height at which branches first occur along the bole - as well as overall tree shape - vary considerably among individuals and are habitat-dependent characteristics. Frequently, Guanacaste trees grow as single specimens in a sunny pasture. Under these conditions, massive, extended, horizontal limbs emerge low on the boles, forming giant, hemispherical, widely spreading crowns. In the forest (where competition for light is intense), trees tend to become taller and branching occurs at a higher level. Tree forms then become somewhat narrower, though crowns are still rounded and hemispherical shapes are maintained by those that have reached the canopy. The bipinnately compound, alternate leaves (20 cm by 17 cm) are confined to the outer shell of the crown, yet they are plentiful enough to make it moderately dense and green. The tiny leaflets (8 mm by 2 mm) number about 36 pairs to a pinna and there are 11 pairs of pinna per leaf. Near its base, the twiggy petiole bares a small, raised, oval gland. Most foliage is shed in December, at the start of the dry season, and trees remain very nearly leafless for the following two months. In late February, a growth surge is initiated that re-establishes a fresh, thick crown by April. Concurrent with crown renewal is the appearance of globular flowers (3 cm) in the axils of the new leaves. Supported by a long pedestal (4 cm), each spherical white head - composed of about fifty individual flowers - sports thousands of thin, filamentous stamens as its major feature. The blossoms themselves each consist of about twenty stamens and a single pistil, bound together at the base by a short, green, tubular corolla and an even shorter calyx. Guanacaste flowers are very fragrant and during intense flowering periods
their odor permeates the air
for many meters in all directions. In Manuel Antonio, flowering
lasts from late February to early April. Surprisingly, no fruiting
activity immediately follows the decline of the blossoms. Rather,
nine or ten months pass before small, green pods first appear
high in the crown (December). They reach full size by February
and finally begin to harvest in March - a full year after flowering
ceased. Guanacaste fruits are large (10 cm), spirally organized
pods that resemble orbicular disks. (Their shape suggests the
usual Mimosaceae fruit - a long, narrow, flattened pod - taken
and wound around an axis perpendicular to its plane.) Made of
thick, soft tissue with a leathery feel, the glossy brown pods
contain about twenty, radially arranged seeds. Guanacaste seeds
(1.5 cm) are brown and marked with a conspicuous light brown or
orange ring. They are also very hard - resembling small stones
rather than tree seeds in their strength and durability. In order
for germination to occur, the hard seed coat must be broken to
enable water to reach the embryo. Otherwise, they will lie dormant
indefinitely. Fruit harvests last from March to April, as the
green pods turn brown in the Guanacaste crown and are slowly shed.
Vigorous trees will produce large crops on a nearly-annual basis.
In June, Guanacaste seedlings can already be seen, germinating
in the moist soil of the early rainy season.
