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Podocarpaceae is a large family growing mainly in the Southern Hemisphere with 18-19 genera and about 170-200 species of evergreen trees and shrubs. The family is a classic member of the Antarctic flora, with its main centers of diversity in Australasia, particularly New Caledonia, Tasmania, and New Zealand, and to a slightly lesser extent, Malesia and South America (in the latter, primarily in the Andes mountains). Several genera extend north of the equator into Indo-China and/or the Philippines. Podocarpus additionally reaches as far north as southern Japan and southern China in Asia and Mexico in the Americas, and Nageia into southern China and southern India. Two genera also occur in sub-Saharan Africa, the widespread Podocarpus and the endemic Afrocarpus.

One species, Parasitaxus usta, is unique as the only known parasitic conifer. It occurs on New Caledonia, where it is parasitic on another member of the Podocarpaceae, Falcatifolium taxoides.

Sciadopityaceae - Umbrella-pine family

The Koyamaki (Sciadopitys verticillata) or Japanese Umbrella-pine, is endemic to Japan. It is the sole member of the family Sciadopityaceae and genus Sciadopitys, a living fossil with no close relatives and known in the fossil record for about 230 million years.

Sciadopitys verticillata foliage

The Koyamaki is an evergreen tree that can grow 15 to 27 meters (50 to 90 feet) tall, with brown main shoots bearing whorls of 7 to 12 centimeters (3 to 5 inches), long flexible green cladodes that look like, and perform the function of, leaves but are actually composed of stem tissues; occasionally, a cladode will be forked and produce a bud in the 'v' of the fork. The cones are 6 to 11 cm (2.5 to 4.5 inches) long, mature in about 18 months, and have flattish scales, which open to release the seeds.

It is a very attractive tree and is popular in gardens, despite its slow growth rate and high cost.

Cupressaceae - Cypress family

Sugi, Cryptomeria japonica, the national tree of Japan.

The Cupressaceae or cypress family includes 27 to 30 genera and 130 to 140 species. Its species are found worldwide in both the southern and northern hemispheres and include cypresses, bald cypresses, junipers, and redwoods. Many are valuable to humans for timber and other products. They are also widely grown in gardens and parks because of their unique beauty. The national trees of Japan and Mexico and the state trees of Louisiana and California in the United States are members of the cypress family.

Cephalotaxaceae - Plum-yew family

The family Cepahlotaxaceae is small, with three genera and about 20 species, closely allied to the Taxaceae, and included in that family by some botanists. They are restricted to East Asia, except for two species of Torreya found in the southwest and southeast of the United States; fossil evidence shows a much wider prehistorical Northern Hemisphere distribution.

These are much branched, small trees and shrubs. The leaves are evergreen, spirally arranged, often twisted at the base to appear two-ranked. They are linear to lanceolate, and have pale green or white stomatal bands on the undersides. The male cones are 4 to 25 mm (0.16 to 1 inch) long, and shed pollen in the early spring. The female cones are reduced, with one to a few ovuliferous scales, and one seed on each ovuliferous scale. As the seed matures, the ovuliferous scale develops into a fleshy aril fully enclosing the seed. The mature aril is thin, green, purple, or red, soft and resinous. Each ovuliferous scale remains discrete, so the cone develops into a short stem with one to a few berry-like seeds. They are probably eaten by birds or other animals which then disperse the hard seed undamaged in their droppings, but seed dispersal mechanisms in the family are not yet well researched.

Taxaceae - Yew family

An Irish Yew (Taxus baccata 'Fastigiata') planted at Kenilworth Castle

The family Taxaceae, commonly called the yew family, includes three genera and about 7 to 12 species, or in other interpretations six genera and about 30 species.

Yews are found around the world, mostly in the Northern Hemisphere. Most are poisonous to humans (the family and generic names have the same root as the word "toxic") and some have traditional medical uses in many cultures. The European Yew, Taxus baccata, had a great importance in Medieval times as the source of the best wood for long bows and was often credited with supernatural powers, being traditionally planted in churchyards. The bark of the Pacific Yew, T. brevifolia, is now being used to make the anti-cancer drug Taxol (Hartzell 1991).

References

  • Dallimore, W., and A. B. Jackson. Revised by S. G. Harrison. 1967. A Handbook of Coniferae and Ginkgoaceae. New York : St. Martin's Press.
  • Earle, C. J. 2006. The Gymnosperm Database. Retrieved June 25, 2007.
  • Hartzell, H. 1991. The Yew Tree Eugene, OR: Hulogosi.
  • Lanner, R. M. 1999. Conifers of California. Los Alivos, CA: Cachuma Press. ISBN 0962850535
  • Pielou, E. C. 1988. The World of Northern Evergreens. Ithica, NY: Cornell University Press. ISBN 0801421160

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