Conifers Garden - Online Tree Nursery

Austrocedrus

Chilean incense-cedar, Florin & Boutelje  1954
Cupressaceae

 

Evergreen trees and shrubs with a single or multiple trunks bearing fibrous, deeply furrowed bark peeling in strips. Densely branched from the base when young with short horizontal or upswept branches to form a dense, conical crown that broadens and flattens with age above a clear trunk two-thirds the height of the tree. Branchlets arising only from lateral leaves, in pairs or alternately, to form flattened, fernlike sprays with distinct upper and lower sides, mostly hidden by the leaves and attached leaf base. Without definite winter buds. Seedling leaves in alternating quartets, needlelike, standing out from and well-spaced on the stem, soon giving way to juvenile lateral sprays. Juvenile and adult leaves in alternating pairs, scalelike, densely clothing the branchlets, differentiated into facial and lateral pairs; the lateral pairs much larger than the facial ones, like large saw teeth in juveniles but the free tip much reduced in adults. Successive facial pairs widely separated by the touching bases of the lateral pairs, some with a round resin gland. Margins of lateral leaves thickened and the whole area inside these margins on the lower side covered with a whitish, waxy stomatal area.

Plants monoecious or dioecious. Pollen cones numerous, single at the ends of lateral branchlets, oblong, with four or five alternating pairs of pollen scales, each scale with three or four round pollen sacs. Pollen grains small (20-30 µm in diameter), spherical, minutely bumpy and with a very faint, small germination pore. Seed cones single at the ends of short branchlets, maturing in a single season, oblong, with two alternating pairs of seed scales, only the inner, larger, paddle-shaped pair fertile. Each scale apparently with intimate fusion of the bract to the seed part, the bract extending almost the whole length of the scale and coming to a small prickle just below its tip, the fertile pair each with two seeds. Seeds oval, with two unequal wings derived from the seed coat, the inner, larger wing expanding across the seed scale, the outer wing a mere fringe. Cotyledons two, each with one vein. Chromosome base number x = 11.

Wood fragrant, soft, light, decay resistant, notably knotty, the yellowish white sapwood moderately distinct from the pale yellowish brown heartwood. Grain even and somewhat coarse, with well-defined growth rings marked by a gradual transition to much smaller and thicker-walled latewood tracheids. Resin canals absent but with widely scattered individual resinous parenchyma cells sometimes concentrated within the latewood.

Stomates in more or less waxy patches on both sides of the lateral leaves (but more prominent on the side facing down). Individual stomates tucked just under four to six subsidiary cells, which are frequently shared by adjacent stomates both within and between rows, and which are topped by a lobed but continuous Florin ring of varying height but do not bear additional papillae. Leaf cross section with a single-stranded midvein accompanied below by a single large resin canal with transfusion tissue in between. Photosynthetic tissue accompanied by scattered sclereids, all loose and spongy without a well-organized palisade layer beneath the epidermis and adjacent discontinuous hypodermis.

One species in southern South America. Austrocedrus is one of the southern hemisphere incense cedars once included within Libocedrus (hence the scientific name, Latin for “southern cedar”). It differs from species of Libocedrus and Papuacedrus in its wood, the thickened margin of the leaves and their arrangement of stomates, and in having the bract tip at the tip of the seed scale rather than in the middle (Libocedrus) or toward the base (Papuacedrus). DNA sequences support its relationship to, but distinction from, the other incense cedars. Although Austrocedrus chilensis is fairly commonly cultivated as a specimen tree in moist, moderate climates, primarily in larger landscapes like parks and botanical gardens, there has been no cultivar selection. Fossils have been found in Miocene deposits of Argentina, where it is found today, but also earlier, in Oligocene sediments in Tasmania across the South Pacific from its present range.

 

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.


 

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