Clusia peninsulae Hammel sp. nov. ined.
Clusiaceae MATAPALO
Tree: Clinging evergreen treelet or aerial shrub (5 m) found growing attached to the trunks of large forest trees – usually well above the ground. Though not directly parasitic, these plants begin life as seedlings perched on limbs or nestled in tree bark. Slowly, their roots grow downward until they reach the soil. Clusias do not harm the trees that harbor them, unless they grow large enough to compete with their hosts for sunlight.
Description: C. peninsulae often has no main trunk, the bulk of its mass being composed of multiple spreading stems or branches. These limbs fan out and away from the host tree, usually just under its crown, forming a secondary crown of considerable dimensions. Clusia roots may be seen wrapped around the host trunk (encircling it) and they extend all the way to the forest floor. The bark is gray and smooth. Twigs and broken bark exude a thick, white, milky sap that is characteristic of all the species in the Clusia genus. Leaves (16 cm by 5 cm) are thick and succulent, smooth, simple, and oppositely arranged. They are dark green with parallel (not netlike) secondary venation and are basically oblanceolate in shape (wider distally than proximally). Many of the blades exhibit a marked asymmetry about their longitudinal axes and are slightly falcate. Drip tips are present as are long petioles (1.5 cm).
Flowers are borne in terminal racemes containing about 10 blossoms each (2.5 cm in diameter). Composed basically of four white petals and a central, mushroom-shaped pistil, the flower sports a bright orange nectar ring around the base of the ovary. Clusia flowering periods are extended events that vary in timing and duration between plants, but generally they last from December through March, peaking in January. Fruits develop as globular berries (3 cm in diameter) soon after the flowers die. Pale green or whitish in color, they show some maroon highlighting as well. Upon maturation, the fruits open into eight wedge-shaped sections. A hollow in each wedge holds a pair of small, elongated white seeds (4 mm by 2 mm) with bright orange arils. Harvests begin in July and last through October.
Similar Species: C. peninsulae is a member of a large plant genus whose species share similar anatomy and growth habits. The Clusias possess thick, succulent leaves, abundant white latex sap, white or pink flowers with a large, central pistil, and a globular fruit that opens into eight wedges exposing brightly ariled seeds. Finally, they all are opportunistic plants, growing below or inside tree crowns and taking advantage of the height and strength of host boles to reach the sunlight rapidly.
Natural History: Flowers in C. peninsulae are visited and pollinated by bees. Attracted by the orange nectar ring, these insects collect this substance in sacs on their legs. Seed dispersal is accomplished with the aid of small birds like Red-legged Honeycreepers (Stiles and Skutch, 1989). These agile aviators eat the arilate fruits, obtaining nutrition from the oily aril. Seeds that survive passage through the birds digestive system are excreted in droppings – many of which land on tree limbs or get caught in bark cracks and crevasses. Here the seeds germinate and begin life as epiphytes, producing aerial roots capable of absorbing necessary nutrients from rainwater and the residues of decay accumulated on tree bark. At this stage in their life cycle, Clusias are particularly prone to drought and desiccation – having no link to soil water supplies – and so are adapted to xeric conditions. The thick, water storing, succulent nature of their leaves along with an impermeable, waxy coating provide them with considerable drought protection. Eventually, thin cord-like roots begin to grow downwards, attempting to reach the ground far below. If they are successful and find the soil, these roots begin to thicken. Growth accelerates, thanks to the continuous and ample supply of water and nutrients obtained from the soil, and ultimately, the Clusia may become large and strong enough to support itself independently of the host tree.
Sunlight is a scarce commodity on the forest floor and the Clusias have invented a way to eliminate the part of the life cycle that would be spent in the shade. They begin life already well placed high in the canopy and grow downwards, rather than the other way around. The Clusias share this growth strategy with the Ficuses (sometimes refereed to as the strangling figs), differing from them in that this latter group generally outgrows and shades its host, eventually killing it. Clusias, in general, appear to remain within the crown and never get large enough to harm the tree they cling to.
Distribution: Clusia is found in all of Manuel Antonio National Park´s primary forests. Endemic to Costa Rica, this species is also known from the Osa Peninsula, the Isla del Caño, and the Golfo Ducle region.
Trees of Costa Rica's Pacific Slope 
