About Epidendrum radicans Pav. ex Lindl.
Epidendrum radicans Pav. ex Lindl. is a herbaceous, terrestrial orchid that grows on the ground (rather than on trees), most often on rocks, and is highly variable in form. It produces long, fleshy aerial roots that grow out from its stems, and reaches a total length of up to 1.5 meters. Its stems are cylindrical, straight, and reed-like, measuring 19 to 125 cm long and 3.5 to 8 mm in diameter. Main stems lie along the growing surface and are somewhat branched, while branches are more or less erect, climbing, or also prostrate. Leaves are alternate, with thick, leathery ovate-elliptic blades that end in a short point (mucronate) at the apex. Leaf blades measure 2 to 9 cm long and 1.2 to 2.5 cm wide, clasp the stem at their base, and sometimes develop a purple color. As a member of Epidendrum subgenus Amphiglottium, it is a sympodial orchid: its stems do not swell into pseudobulbs and are covered in overlapping sheaths, it produces a terminal inflorescence that is covered at its base by tight overlapping sheaths, and its lip is fused to the column all the way to the column's apex. Like other members of section Schistochila, the lip of E. radicans is divided into three lobes, and it shares the lacerate (irregularly torn) lobes that are typical of subsections Carinata and Tuberculata. It differs from other lacerate Schistochila species by producing roots along most of its stem.
In terms of ecology, E. radicans is distributed across Mexico, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, Venezuela, and Colombia. It is common growing on rocks in full sun, found in mountain cloud forests at altitudes between 900 and 2500 meters above sea level, as well as in oak forests, semi-evergreen forests, riparian vegetation, and evergreen scrub. It is part of a complex of several unrelated but ecologically similar weedy species with orange flowers, which includes various Asclepias species. Species in this group share both pollinators and habitat, and are thought to exhibit convergent evolution, where unrelated species develop similar physical characteristics in response to shared evolutionary pressures. Paulette Bierzychudek studied pollinator behavior in the apparent complex made up of E. radicans, Asclepias curassavica, and Lantana camara, but did not find clear evidence that floral mimicry affected pollination rates for any of the three species.
For cultivation, E. radicans is easily propagated from tip cuttings and keikis (pups) that form on its stems. It grows best at temperatures between 10° and 27°C (50° and 80°F), suited to USDA hardiness zones 10–12, and tolerates full sun or partial shade in loamy, sandy, well-drained soil. During summer, two hours of direct sunlight may scorch and dehydrate the plant, and soil must not stay soggy or hold excess water. It tolerates low-nutrient growing areas and does not require extensive maintenance. It can be grown in garden beds, and needs large containers when potted; infrequent repotting will restrict its growth and potential blooming. Support may be needed to keep growth compact and upright, though stems will still grow and bloom even if they droop or spread. A slow-release fertilizer can support plant vitality, and mulch is recommended to reduce weed competition and maintain soil moisture. Potential pests affecting cultivated plants include mealybugs, spider mites, scale, thrips, whitefly, and root mealybugs. Potential diseases include root rot, leaf spot disease, rust, mosaic virus, black rot, botrytis petal blight, powdery mildew, and southern blight. Generally, however, the plant is rarely troubled by pests or diseases, as it adapts to a much wider range of growing conditions than other orchid species.
