Conifer, (KOH nuh fuhr) or (KAHN uh furh), is any one of a large group of trees or shrubs that bears it's seeds in cones. Most conifers have tall, straight trunks and narrow branches and grow in cold or cool climates. Common conifers include cedars, pines, spruces, firs, cypresses, hemlocks, junipers, larches, redwoods, sequoias, and yews. The cycad plant also bears cones, but it is not considered to be a conifer.

Conifers are one of the oldest groups of woody plants. Conifer fossils have been found in rocks that are about 300 million years old. Conifers include the largest, tallest, and oldest living things. The largest giant sequoia is about 275 feet (83.8 meters) high, and the base of its trunk has a circumference of 103 feet (31.4 meters). Redwoods, the tallest living trees may tower more than 360 feet (110 meters high).

Some bristlecone pines are more than 4,600 years old.

Conifers form about 39 per cent of the world’s forests. In North America, most of the wood used in houses and other buildings comes from conifers, especially Doulgas-fir and loblolly pine. Conifers also provide much wood pulp for making paper and cardboard, In addition, millions of conifers are used every year as Christmas trees.

Most conifers are evergreen and have small, needle-like leaves. Other conifers, including red cedars, and cypresses, have tiny, scale like leaves that cling to the stem. These trees are also evergreen. Larches and bald cypresses are conifers but they lose their leaves every year.

Conifer cones range from less than 1/2 inch (1.3 centimeters) long to more than 2 feet (61 centimeters) long. Conifers have two types of cones-male and female. In most conifers, both types grow on the same plant. The soft male cones produce and release pollen, then shrivel and die. The female cones are larger and become woody with age. Each of their scales has two structures called ovules, which contain eggs (female reproductive cells). Wind carries pollen from the male cones to the female cones, where the pollen fertilizers the egg. The ovules then develop into seeds. After the seeds become fully formed, they fall from the cones.

A few conifers have unusual, fleshy cones. Juniper seed cones resemble blueberries. Yew seed cones look tile red berries with a single, large seed.

Gymnosperm, (JIHM nuh spurm), is the name of one of two large groups of seed plants. The plants have naked, or uncovered, seeds. The term gymnosperm comes from two Greek words meaning naked and seed. The other group, called the angiosperms, consists of plants whose seeds have a protective ovary (seed case).

Gymnosperms are woody perennials which are among the largest and oldest living plants. There are about 800 species. About 600 are conifers such as the pines, fir, spruces, and balsams. These cone-bearing trees make up the largest division (group) of gymnosperms. The tropical and subtropical cycads, also gymnosperms, are among the most primitive living seed plants. The ginkgo, also called the maidenhair tree, is another primitive gymnosperm.

Many of the gymnosperms are evergreen with a wide variety in the structure of the leaves. They do not bear flowers. Tiny male cones produce the pollen, which is usually spread by the wind. The naked, or exposed seeds are borne between the scales of the female cones and drop when they become ripe. Gymnosperms provide the source of many valuable products such as tar, turpentine, rosin, and timber.

Seed development in gymnosperms. The reproductive organs of a gymnosperm are in its cones. A gymnosperm has two kinds of cones, female seed cones and male pollen cones. Each scale of a seed cone has two ovules on its upper surface. Cell division occur in the ovules, and each ovule produces a spore that grows into a megagametophyt. This tiny female plant produces egg cells. The scales of a pollen cone have structures that undergo cell divisions and produce spores. These spores develop into pollen grains.

The wind carries pollen grains from the pollen cones to the seed cones. The pollen gets stuck to a sticky substance near the ovules and begins to grow pollen tubes. Each pollen grain has two sperm cells. After the pollen reaches an ovule, one of the sperm cells fertilizes the egg cell, forming the embryo. The other sperm cell disintegrates. The megagametophyte becomes the food storage tissue of the seed. The seed coat develops from the outer layers of the ovule.

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