Alerce, J.D. Hooker ex Lindley  1851
Cupressaceae

Fitzroya - Alerce description

Evergreen trees with a single massive trunk clothed with fibrous, deeply furrowed bark peeling in vertical strips. Crown conical to dome-shaped, sparsely branched with slender horizontal or slightly drooping branches, some of which thicken as major limbs. Branchlets alternate, radiating in three dimensions. Winter buds of unexpanded leaves. Leaves in alternating trios, scalelike to clawlike, standing out from the twigs with a long free tip and without glands.

Plants usually dioecious. Pollen cones single in the leaf axils near the ends of the branchlets, with five to eight alternating trios of pollen scales. Each scale with two six pollen sacs on the inner face of a triangular blade at the tip of a short, slender stalk. Pollen grains small (30-40 µm in diameter), spherical, minutely bumpy. Seed cones well separated, single at the tips of ordinary branchlets, maturing in a single season, roughly spherical with three or four alternating trios of seed scales, the inner trio forming a sterile central column, the fertile middle trio(s) and the sterile outer trio radiating from the base of the cone. Fertile scales woody, touching but not overlapping when closed, consisting of closely united bract and seed scales, with a prominent bract point below the tip. Seeds oval, one or two per fertile scale, with two or three equal wings (or one smaller or rudimentary) extending the length of and as wide as the body. Seed wings formed as outgrowths from the seed coat. Cotyledons two, each with one vein. Chromosome base number x = 22.

Wood unscented, light, soft, and highly decay resistant. Sapwood narrow, yellowish white, sharply contrasting with the pale to dark reddish brown to reddish orange heartwood often contrastingly streaked with lighter and darker hues, but losing its brightness with age. Grain fairly even and moderately fine, with evident growth rings marked by a somewhat abrupt transition to a narrow band of much smaller and thicker-walled latewood tracheids. Resin canals absent but with scattered individual resin parenchyma cells more frequent in the outer part of the growth increment.

Stomates in two prominent white stomatal bands both above and beneath. Each stomate sunken beneath and almost hidden by the four to six subsidiary cells that are covered by a very thick cuticle that does not rise further to form a Florin ring. Leaf cross section with a single-stranded midvein above a single large resin canal and flanked by wedges of transfusion tissue. Photosynthetic tissue with a weakly developed palisade layer beneath the epidermis and adjoining thin, nearly continuous (except under the stomatal bands) hypodermis.

One species in the southern Andes and coast ranges of South America.

The name of the genus honors British Vice-Admiral Robert Fitz Roy (1805-1865), who was captain of the Beagle during its second voyage around the world (1831-1836), with a chief goal of to mapping the coast and waters of southern America, where the tree was an important and conspicuous forest component. This expedition, of course, is much better known for the inspiration it gave to the ship’s naturalist, Charles Darwin, then in his 20s. Although the genus is in Cultivation to a limited extent in botanical and estate gardens in moderate temperate regions of high precipitation, there has been no cultivar selection.

Fitzroya differs from Australian Callitris and Actinostrobus, the other southern hemisphere Cupressaceae with leaves in whorls of three, in its expanded leaf tips with prominent stomatal bands, and its rounded seed cone scales. DNA studies agree with the long-held speculation based on morphology that it is closest to the Tasmanian Diselma (and to African Widdringtonia), despite the fact that these genera have a paired leaf arrangement. The only known fossil Fitzroya has been described from the Oligocene of Tasmania, where it grew with other plants now also found growing with Fitzroya in South America.

References

• Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
• Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
• IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.