Download Sample

Pineapple
Pineapple is the common name for a flowering plant
family, characterized by unique water-absorbing leaf scales
and regular three-parted flowers. The leaves are spirally
arranged sheaths or blades, usually occurring in layers.
The plant embryos have one seed leaf. The family, which
contains more than 2000 species placed in 46 genera, is
almost exclusively native to the tropics and subtropics of
America, with one species occurring in western Africa.
Many species are now cultivated around the globe,
however. The most economically important species is the
familiar pineapple. A few species are sources of fiber,
others are cultivated for their showy flowers or foliage. The
family constitutes an order, and the term bromeliad is used
for its members.
Bromeliads exhibit an interesting gradation from relatively primitive to highly
evolved forms, with tremendous variations in size and adaptations to their
environments. Primitive members include a genus that teaches a height of 10
m(30 ft) and grows high in the Andes. Plants of this genus are terrestrial and
have elongated stems, fully developed roots, leaves with narrow petioles, and
hairs that retard water loss by providing a dense covering. A second stage in
bromeliad advancement is the familiar pineapple, native to South America but
now widely cultivated in tropical areas, primarily for its sweet, juicy fruit.
Pineapples are terrestrial, growing to about 1 m(about 3 ft), but the stems are
short and the petioles are expanded, fitting together to form a water-holding
tank at the base of the plant. The leaves act as catchment basins and the tanks
as reservoirs. Water is absorbed from the tank as needed by adventitious roots
or leaf hairs. An extreme form of bromeliad adaptation is reached in Spanish
moss; it has roots only when young, water absorption being taken over by
specialized leaf scales. Spanish moss occurs throughout the range of the order
as an epiphyte, growing on other plants for support.
Bromeliads with water-holding bases have developed complex
relationships with other organisms. Within these reservoirs live
ecological communities ranging from unicellular algae and protozoans
to aquatic flowering plants and insects, crabs, and frogs. Bromeliads
receive dissolved nutrients from their wastes and decomposing
remains and are thereby less dependent on roots in the soil.
The pineapple was probably first domesticated in the high plateaus of
central South America; it was widely planted for its fiber before
Europeans first saw it in the Caribbean. Thereafter, cultivation spread
to warm regions around the globe. Hawaiian plantations produce
almost a third of the world’s crop and supply 60 percent of canned
pineapple products. Other leading producers are China, Brazil, and
Mexico.