| Bromeliaceae (the bromeliads) is a family of
monocot flowering plants of around 3,170 species native
mainly to the tropical Americas, with a few species found in
the American subtropics and one in tropical west Africa,
Pitcairnia feliciana. It is the one of the basal families
within the Poales and is unique because it is the only
family within the order that has septal nectaries and
inferior ovaries. These inferior ovaries characterize the
Bromelioideae, a subfamily of the Bromeliaceae. The family
includes both epiphytes, such as Spanish moss (Tillandsia
usneoides), and terrestrial species, such as the pineapple (Ananas
comosus). Many bromeliads are able to store water in a
structure formed by their tightly-overlapping leaf bases.
However, the family is diverse enough to include the tank
bromeliads, grey-leaved epiphytic Tillandsia species that
gather water only from leaf structures called trichomes, and
a large number of desert-dwelling succulents.
The largest bromeliad is Puya raimondii, which reaches
3–4 m tall in vegetative growth with a flower spike 9–10 m
tall, and the smallest is probably Spanish moss.
Bromeliads are one of the more recent plant groups to
have emerged. The greatest number of primitive species
reside in the Andean highlands of South America where they
originated in the tepuis of the Guyana Shield. The most
basal genus Brocchinia is endemic to these tepuis and is
placed as the sister group to the remaining genera in the
family. The west African species Pitcairnia feliciana is the
only bromeliad not endemic to the Americas, and is thought
to have reached Africa via long-distance dispersal
approximately 12 million years ago.
Humans have been using bromeliads for thousands of years.
The Incas, Aztecs, Maya and others used them for food,
protection, fiber and ceremony, just as they are still used
today. European interest began when Spanish conquistadors
returned with pineapple, which became so popular as an
exotic food that the image of the pineapple was adapted into
European art and sculpture. In 1776, the species Guzmania
lingulata was introduced to Europe, causing a sensation
among gardeners unfamiliar to such a plant. In 1828, Aechmea
fasciata was brought to Europe, followed by Vriesea
splendens in 1840. These transplants were successful enough
that they are still among the most widely grown bromeliad
varieties.
In the 19th century, breeders in Belgium, France and the
Netherlands started hybridizing plants for wholesale trade.
Many exotic varieties were produced up until World War I,
which halted breeding programs and led to the loss of some
species. The plants experienced a resurgence of popularity
after World War II. Since then, Dutch, Belgian and North
American nurseries have largely expanded bromeliad
production.
Collectors
Édouard André was a French collector/explorer whose many
discoveries of bromeliads in the Cordilleras of South
America would be influential on horticulturists to follow.
He was felt to have served as a source of inspiration to
20th century collectors, in particular Mulford B. Foster and
Lyman Smith of the United States and Werner Rauh of Germany.
Description
Bromeliads are a varied group of organisms, adapted to a
number of climates. Foliage take different shapes, from
needle thin to broad and flat, symmetrical to irregular,
spiky and soft. The foliage, which usually grows in a
rosette, is the most widely patterned and colored of any
plant in the world. Leaf colors range from maroon, through
shades of green, to gold. Varieties may have leaves with
red, yellow, white and cream variegations. Others may be
spotted with purple, red, or cream, while others have
different colors on the tops and bottoms of the leaves.
The inflorescence produced by bromeliads are also
regarded as considerably more diverse than any other plant
family. Some flower spikes may reach 10 meters tall while
others only measure 2–3 mm across. Upright stalks may be
branched or simple with spikes retaining their color from
two weeks up to twelve months, depending on species. In some
species the flower remains unseen, growing deep in the base
of the plants.
Root systems vary according to plant type. Terrestrial
bromeliad species have complex root systems that gather
water and nutrients while epiphytic bromeliads only grow
hard, wiry roots to attach themselves to trees and rocks.
Some bromeliads are faintly scented while others are heavily
perfumed. Blooms from the species Tillandsia cyanea resemble
the smell of clove spice.
One study found 175,000 bromeliads per hectare (2.5
acres) in one forest; that many bromeliads can sequester
50,000 liters (more than 13,000 gallons) of water.
A wide variety of organisms take advantage of the pools
of water trapped by bromeliads. A study of 209 plants from
the Ecuadorian lowlands identified 11,219 animals,
representing more than 300 distinct species, many found only
on bromeliads; for instance, some species of ostracods,
small salamanders approximately 2.5 centimeters (1 inch) in
length and tree frogs. Jamaican bromeliads are home to
Metopaulias depressus, a reddish-brown crab 2 cm (0.75 inch)
across, which has evolved social behavior to protect its
young from predation by Diceratobasis macrogaster, a species
of damselfly whose larvae live in bromeliads. Some
bromeliads even form homes for other species of bromeliads.
Adaptations
The plants within the Bromeliaceae are able to live in a
vast array of environmental conditions due to their many
adaptations. Trichomes, in the form of scales or hairs,
allow bromeliads to capture water in cloud forests and help
to reflect sunlight in desert environments. Some bromeliads
have also developed an adaptation known as the tank habit,
which involves the bromeliads forming a tightly bound
structure with their leaves that helps to capture water and
nutrients in the absence of a well-developed root system.
Bromeliads also use crassulacean acid metabolism (CAM)
photosynthesis to create sugars. This adaptation allows
bromeliads in hot or dry climates to open their stomates at
night rather than during the day, which prevents them from
losing water.
Distribution
Plants in the Bromeliaceae family are widely represented
in their natural climates across the Americas. One species
can be found in Africa. They can be found at altitudes from
sea level to 4200 meters, from rainforests to deserts.
Approximately half the species are epiphytes, some are
lithophytes, and some are terrestrial. Accordingly, these
plants can be found in the Andean highlands, from northern
Chile to Colombia, in the Sechura Desert of coastal Peru, in
the cloud forests of Central and South America, in southern
United States from southern Virginia to Florida to Texas,
and in far southern Arizona.
Subfamilies
The family Bromeliaceae is organized into 3 subfamilies:
Bromelioideae (32 genera, 861 species)
Pitcairnioideae (16 genera, 1030 species)
Tillandsioideae (9 genera, 1277 species)
Cultivation and uses
Only one bromeliad, the pineapple (Ananas comosus), is a
commercially important food crop. Bromelain, a common
ingredient in meat tenderizer, is extracted from pineapple
stems. Many other bromeliads are popular ornamental plants,
grown as both garden and houseplants. |
