EPIPHYTES AND CLIMBERS Epiphytes are plants that grow on other plants. They use other plants for support but do not parasitise them, although at first sight they might be thought to be parasitic. Many orchids and bromeliads are epiphytes in tropical rainforests, and many ferns and mosses are epiphytes in temperate rainforests. In these cases there is sufficient water, or humidity in the air, to sustain the epiphytes. Epiphytes are much less common in desert environments, where the air is characteristically dry. But in parts of the Sonoran Desert in Baja California (Mexico) there is sufficiently humid air blowing across from the Pacific Ocean to support extensive growth of lichens and of a flowering plant called ball moss on the trunks and stems of trees and shrubs. A few other desert plants are rooted in the soil but climb over other plants for support. One such example in deserts is the rambling milkweed (Sarcostemma cynanchoides), which climbs over shrubs and often completely covers them. It can sometimes be confused with dodder, especially in winter months when its leaves and stems have dried and it appears as a mass of yellowish strands. But in the growing season it has green stems and narrow green leaves. It is not a parasite - it simply climbs over other plants for support. Rambling milkweed (Sarcostemma
cynanchoides) with clusters of star-shaped purple
flowers Dense colonies of the
lichen Ramalina (commonly known as Spanish moss)
on the trunk of a boojum tree (Cirio) Lichens on the trunk of
cliff spurge (Euphorbia misera) Ball moss (Tillandsia
recurvata) |
