Xylopia frutescens Aubl.
Annonaceae
TRUP-KRO, MALAGUETO
Occasional evergreen tree (8-12 m) found growing abundantly – but exclusively – along one particular Manuel Antonio National Park (MANP) trail. This path, a former rural roadway that provided a link between the third beach (Playa Blanca) and a large cattle farm located near the mouth of the Naranjo river, was used to transport livestock arriving by boat from Guanacaste. Imported seeds, left behind by these farm animals, probably introduced this – and two other tree species – to Manuel Antonio.
Description: Xylopia‘s trunk (25 cm) is straight, cylindrical and clad in smooth, dark-gray bark. Branches diverge from the bole only along the upper third of its length, lower ones having died away as the tree grew taller. (Circular scars impressed into the bark bear witness to these old limbs). Emerging at right angles, these slim branches tend to droop as they extend laterally away from the pole-like bole, and they end as fine twigs thinner than a toothpick. The Xylopia crown is pyramidal in shape, though narrow, and it is made moderately dense by the tree’s finely textured, but abundant dark green foliage. Leaves (6 cm by 1.5 cm) are simple, alternate, and smooth. Very narrowly elliptical in shape, the blades are marked by pronounced mid-ribs that end in short, 3 mm petioles. New twig and foliage growth begins in July and lasts through September.
Xylopia‘s creme-colored flowers appear in small panicles from leaf axils. Each blossom consists mainly of three, thick, spongy petals covered with a fine, velvety pubescence and fused at the base. Set in a small green calyx of three triangular sepals, the corolla maintains a roughly cylindrical shape (actually resembling a minute bowling pin) since the long (1 cm) but narrow petals are closed most of the time – hiding the stamens and pistil within. Flowering periods are annual, precisely timed, and well synchronized events that last from May though June.
Almost immediately thereafter, small green knobs become visible along the branches and amid the foliage. These immature fruits remain more or less dormant until October, when they finally begin to enlarge rapidly. Still, they do not ripen until eight months after flowering ends. Mature fruits (1 cm) are capsules borne in small clusters located largely on the bare portions of the twigs behind the flush of new leaves. (Though the flowers were formed in current leaf axils, the continued growth of the twig during the protracted interval before fruit development left these latter structures behind on the branches.) In form, each capsule resembles the fattened head of a golf club. Turning from green to yellow, ripe fruits split longitudinally and reveal a nearly-fluorescent pink interiors with two, small (6 mm by 3 mm) rod-like, black seeds embedded in each. Harvests last from late January or early February though March, and they are consistent in annual timing and size.
Similar Species: The narrowness of Xylopia leaves and the fine texture that they give to its crown are unusual characteristics, especially in a tree of this small size. Also, Xylopia trees harbor some form of fertility during every month of the year except April, and the presence of either flowers or fruits in the crown allows the positive identification of this species.
Natural History: Xylopia fruits are largely foraged by birds, with Baltimore Orioles and Chestnut-sided Warblers among those most frequently sighted feeding from its branches.
The reason for the unusual distribution of Xylopia trees in Manuel Antonio National Park is subject to some speculation. There are, in fact, at least two other species that share the same, peculiar range – being found exclusively along the old “Lutz Road”, a muddy trail that leads south across the park and ends at a large cattle farm owned by the family of the same name. One of the species, Bellucia grossularioides, is another extremely abundant tree – but again only among the vegetation that fringes this trajectory – it is not found anywhere else in the park. The other, Samanea saman, is much less common.
According to people who have lived in the area for decades, the Lutz road was once used to drive cattle from Playa Blanca to the Lutz farm. Boats carrying livestock from Guanacaste would land at the third beach (chosen for its calm surf) and farm animals would be unloaded and moved overland to the Rio Naranjo ranch. Seeds present in the food that these cattle ate in their original pastures could have survived the trip (in their digestive systems) and been deposited along old Lutz road during the drives. Samanea pods are known to be favored by cattle, and Bellucia fruits are large, edible, and equally appetizing. It thus seems plausible that these three tree species were inadvertently introduced to Manuel Antonio by cattle drives which took place some sixty years ago.
Uses: Zamora (1989) sites a study by Standley and Steyermark (1946) that says indigenous people of what is now Honduras used this species to make lances for fishing.
Distribution: In MANP, Xylopia is only found along the edges of the “Lutz Road”, a trail that crosses the heart of the park and that links it with the cattle ranch of the same name. It ranges from Guatemala to southern Brazil.
Trees of Costa Rica's Pacific Slope 