One bromeliad's water tank held a frog, an ant colony and a centipede
Many bromeliads grow leaves in a tight rosette that forms a natural tank holding up to 10 litres. These pools become miniature ecosystems. One was found housing a small frog, an ant colony, spiders, beetles, a centipede, an earthworm and even a tree seedling. The pineapple is a member of the same family.
Bromeliaceae holds about 3,700 species in some 80 genera, almost all native to the tropical and subtropical Americas. The single exception, Pitcairnia feliciana, grows in West Africa, probably having crossed the ocean by long-distance dispersal about 12 million years ago. The family runs from Spanish moss, which hangs from trees, to the ground-dwelling pineapple, and from sea level to 4,200 metres. The giant Puya raimondii grows 3 to 4 metres tall and sends up a flower spike of 9 to 10 metres, while some Tillandsia species are tiny.
Their success comes from inventive ways of getting water. Tank species collect it in their leaf bases, capturing nutrients too even without strong roots. Grey-leaved Tillandsias rely on scales or hairs called trichomes that absorb moisture straight from the air, and Spanish moss has only a vestigial root system. In deserts those same trichomes reflect sunlight. Many species use CAM photosynthesis, opening their pores at night to lose less water, and both that trick and the habit of living on other plants evolved several times within the family.
Bromeliads probably originated about 100 million years ago on the tepuis, the table mountains of the Guiana Shield, where the most primitive genus, Brocchinia, still lives. Yet the modern subfamilies only split around 19 million years ago, a long gap hinting at much speciation and extinction. Around 15.4 million years ago, one branch spread into northern South America and exploded into new species as the Andes rose rapidly, dragging hummingbird pollinators along in their own diversification. A later burst, about 5.5 million years ago, produced many tank-forming epiphytes in the humid mountains of Brazil's Serra do Mar.
Flowers carry three sepals and three petals, often framed by brightly coloured bracts, and are pollinated by insects, hummingbirds and bats, or rarely wind. In the United States, wild bromeliads range from southern Virginia to Florida, Texas and far southern Arizona.
Source: Bromeliaceae
