Conifer

Conifer, common name for a group of plants that is characterized by seed-bearing cones and that includes about 600 of the 740 or so known species of gymnosperms, plants with seeds that are not enclosed in an ovary. Conifers are known from fossils more than 290 million years old. Although more species of conifers once existed, they are still a widely distributed group and are one of the world's most important renewable resources. In late 1994, representatives of a group of conifers widespread in the Cretaceous period were discovered in the Wollemi National Park, near Sydney, Australia. Thirty-nine trees, the tallest of which reaches a height of 40 m (130 ft), were found in a remote area of the rainforest. Fossils of the ancestors of the newly discovered trees exist, but scientists had believed that this particular group had become extinct 40 million years ago.

Conifers, like flowering plants (see Angiosperm), reproduce by means of seeds, which contain food tissue and an embryo that will grow into a plant. The seeds are borne on the scales of female cones rather than being surrounded by carpel tissue, and the pollen is produced in separate male cones rather than in anthers. Pollination in conifers is dependent on wind currents to blow the abundant yellow pollen from the male cones to the female ones. Conifers usually have needle-shaped or scale-like leaves, and nearly all are evergreen. The typically erect growth form of conifers is due to strong apical dominance, in which the influence of plant hormones at the apex or tip of the tree inhibits branching lower down. They vary in size from shrubs to the giant sequoias. See Cedar; Cypress; Douglas Fir; Fir; Hemlock; Juniper; Larch; Pine; Sequoia; Spruce; Yew.

Scientific classification: Conifers constitute the division Gymnospermae or Pinophyta. The two orders of conifers are Coniferales (or Pinales) and Taxales. The newly discovered Australian conifers belong to the family Auracariaceae, a family of primitive trees.