Britannica Illustrated Science Library: Plants, Algae, and Fungi by Encyclopedia Britannica

Author:Encyclopedia Britannica [Britannica, Encyclopedia]
Language: eng
Format: epub
Published: 2011-10-29T23:50:35+00:00

56 SEED PLANTS

PLANTS, ALGAE, AND FUNGI 57

Conifers

LEAFLET

SCALE

DISPERSION

Bract Scale

The ovuliferous scales

generate a greenish

A re effectively the most representative of the gymnosperms, a group gelatin containing the

of plants with seeds but not flowers. Through the fossil record it Cuticle

female gametes. The

gametes are freed when

is known that conifers have existed for more the sac that contains them

than 390 million years. Their leaves are usually Gametophyte

opens. A forest fire can

promote reproduction by

needle-shaped and perennial. They are woody causing the sac to open.

plants that reproduce by means of seeds that contain tissues and an embryo that grows until it becomes an adult plant.

Pine Cones

The female cone contains ovules

that are situated among its

ovuliferous scales. The cones are woody

YOUNG LEAVES

and are usually found in the upper

branches of the tree. The male cones are

are covered by a

not woody and are usually found in the

protective capsule.

lower branches. When the ovules of a

female cone are pollinated, the resulting

seeds need about three years to mature

inside the cone. Mature ovules are

popularly called pine nuts.

FEMALE CONE

Small and light, it is

likely to be pollinated

as soon as it appears.

Bract

LEAVES

Scales

Grouped in sets of two,

they have elongated

shapes. They carry out

photosynthesis.

Ovuliferous

Scales

Classification

The name “conifer” is sometimes erroneously believed to derive from pine trees' conical shape. In reality, there are other forms of coniferous plants.

CLOSED

OPEN

CONES

ARAUCARIA

PINE

CEDAR

Araucariaceae

Pinaceae

Taxodiaceae

The male and female cones

are generally not located

on the same branch.

Pine Nuts

MATURE CONE

Good Wood

Three years after the

Pine nuts have long been used with honey and sugar to make pastries. When summer arrives, The great majority of conifers are evergreens, cone appears, its seeds

harvested pine cones are placed in the sun, which causes although some, such as larches (tamarac), are are ready to disseminate.

them to open. The pine nuts are then shaken loose from deciduous. Conifers are the tallest and most long-lived trees, their cones and gathered. In traditional processing the and they provide most of the wood used in industry. Most pine nuts are soaked in water to remove their outer conifers form new shoots during the summer. They produce covering, which floats to the surface. The pine nuts are 14° F (-10° C)

a resinous substance that protects them from freezing then run between two closely spaced mechanical rollers during winter. This adaptation permits vital nutrients to OR LESS: TYPICAL AVERAGE

to crack their inner shells. Finally, the pine-nut meat is continue to circulate through their vascular systems, even in January temperature across the extensive

separated from the shell by hand.

very cold weather.

coniferous forests of the Northern Hemisphere.

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