BROMELIAD

( familyBromeliaceae ) any of more than 2,500 species of predominantly tropical plants, many of which live on the surface of other plants (epiphytes). The pineapple (Ananas comosus) is a terrestrial member, and Bromeliaceae is often called the pineapple family. This family also constitutes the plant order Bromeliales. Puya raimondii. With the exception of one African species, bromeliads are native to tropical America and the West Indies. They grow in a variety of forms, from the fibrous and hanging Spanish moss (Tillandsia usneoides) to the gigantic Puya raimondii of Peru and Bolivia, which grows in the form of a tree to more than 9 metres (30 feet). In most cases, however, bromeliads are short-stemmed with stiff, pointed leaves that are often edged with spines or are coloured near their base. The leaves are arranged in a single rosette, with the leaf bases of some species overlapping to form a water-retaining pool; these species are called tank bromeliads. From the pool, the plant absorbs nutrients from leachate (rain that has passed through a higher layer of the forest canopy). Tank bromeliads such as Vriesea have been shown to harbour more than 250 species of small animals among the leaf bases and in the tank itself. (See rainforest ecosystem sidebar, Life in a Bromeliad Pool.) The leaves of most epiphytic bromeliads are adapted to function as roots. Scales that cover the leaf surface can be retracted to conserve water or expanded to increase surface area and nutrient uptake. Bromeliads have three-parted flowers like lilies, but with contrasting sepals and petals; common colours are green, red, and purple. The flowers are sometimes borne on a long spike with brightly coloured leaflike structures (bracts) below the blooms or along the spike itself. Hummingbirds, attracted to the flowers' nectar, are the primary pollinators. The resulting fruits of most bromeliads are fleshy, but others are dry. Bromeliad (Aechmea fasciata). Several bromeliads, in addition to the pineapple, are economically important. Spanish moss is used as packing material, and some species of Aechmea, Ananas, Bromelia, Neoglaziovia, and Puya contain fibres that are made into rope, fabric, and netting. Bromeliads are often cultivated indoors as ornamentals for their colourful flowers and foliage. Among them are Aechmea, Billbergia, Cryptanthus, Dyckia, Guzmania, Hechtia, Neoglaziovia, Neoregelia, Nidularium, Puya, Tillandsia, and Vriesea. Other genera, such as Androlepis, are displayed in conservatories. The pinguin (Bromelia pinguin), a red-flowered plant with sword-shaped leaves about 1.2 to 1.8 metres (4 to 6 feet) high, is useful as a hedge plant. The family Bromeliacae consists of three major subfamilies (Bromelioideae, Pitcairnoideae, and Tillandsioideae) and a possible fourth (Navioideae) for the aberrant genus Navia, which is otherwise included in Pitcairnoideae.