Chamaecyparis
False cypress, Spach 1841
Cupressaceae
Chamaecyparis - False cypress description
Evergreen trees with a single to multiple straight trunks clothed in fibrous, furrowed bark that peels in long, thin strips. Open-grown trees densely branched from the base with upwardly arcing branches drooping at the tips. Crown conical to cylindrical, even when raised far above the ground on a bare trunk in mature forest-grown trees. Branchlets emerging alternately from lateral leaves on either side or just along the far side of a central shoot to form flattened, fernlike, horizontal or drooping sprays. Without definite winter buds. Seedling leaves in alternating quartets giving way to alternating pairs, needlelike, standing out from and well-spaced on the stem, soon replaced by adult branchlets (except on permanently juvenile cultivars, the retinosporas). Adult leaves in alternating pairs, scalelike, overlapping, the facial and lateral leaves similar in size but the lateral leaves folded around the twig, keeled or not and with or without a resin gland.
Plats monoecious. Pollen cones numerous, each single at the tip of a branchlet, oblong. Pollen scales in three to eight alternating pairs, each scale with two to four pollen sacs. Pollen grains small (25-35 µm in diameter), spherical, minutely bumpy, with or without a small, ill-defined, circular germination pore. Seed cones numerous, single at the tips of short side branchlets, maturing in a single season, spherical to oblong, with three to seven alternating pairs of centrally attached seed scales. Each seed scale interpreted as derived from intimate fusion of the bract with the seed portion, the external face broadly hexagonal with a central horizontal line dividing the upper seed-bearing portion from the lower bract portion. Bract with a free, pointed, triangular tip. Uppermost pair of scales often fused into a single rodlike structure, the middle pairs fertile with (one or) two to four seeds per scale. Seeds oval, with two equal wings derived from the seed coat running the length of the body and about as wide. Cotyledons two, each with one vein. Chromosome base number x = 11.
Wood slightly to strongly fragrant, light, soft to moderately hard and strong, resistant to decay, with white to pale yellow sapwood sharply contrasting with the light yellowish brown to pinkish brown heartwood. Grain fairly even and very fine to moderately coarse, with well-defined growth rings marked by an abrupt transition to a few to several rows of smaller, thicker-walled latewood tracheids. Resin canals absent but with a fair number of individual resin parenchyma cells partially scattered through the growth increment and often concentrated in narrow bands.
Stomates arranged in patches or bands of varying position among the species, at least some patches conspicuous with deposits of whitish wax. Each stomate sunken beneath and largely hidden by the four to six surrounding subsidiary cells, which are often shared between adjacent stomates within and between rows, and which are topped by a steep, high, nearly continuous Florin ring. Sometimes also with a partial, irregular outer circle of subsidiary cells, and these and other epidermal cells often bearing large, round to greatly elongated papillae. Leaf cross section with a single large resin canal (which does not extend the whole length of the leaf) tucked under the single-stranded midvein, which is flanked by patches of transfusion tissue. Photosynthetic tissue forming a well-developed palisade of several cell layers all over the exposed portion of the leaf beneath the epidermis and thin, nearly continuous hypodermis but most of the photosynthetic volume inside consisting of spongy mesophyll laced with conspicuous large air spaces.
Six species in North America, Japan, and Taiwan.
Species of Chamaecyparis have a long history of cultivation. Because so many cultivars have been selected each species constitutes a separate cultivar group for naming purposes under the International Code of Nomenclature for Cultivated Plants. As a consequence, you can find the same cultivar name (especially among older, Latinized ones) applied to two or more species unlike in most other conifer genera. Cultivar selection has embraced almost every vegetative aspect of the plants. There are permanently juvenile cultivars (called retinosporas and formerly sometimes treated as a separate genus), ones with sparsely branched foliage (the threadleaf or filifera types) or more densely branched, and with spays that may be unusually elongated or foreshortened and exceptionally flat or intricately twisted and three-dimensional. Solid foliage colors embrace an enormous spectrum of greens, blues, and golds (and purples in winter), and variegated cultivars are legion. Growth habits range from enormous trees to compact dwarfs, with stiffly up-thrust dolorously weeping branching, so much so in some cultivars that the plants never pick themselves up off the ground but spread from a central pile like a fountain. It is no exaggeration to say that there is a Chamaecyparis cultivar (or a few dozen) for virtually every position and design requirement in any garden (in an appropriate climatic zone, of course), from the smallest patch of green to the most monumental estate.
Even the smaller species of the genus. Chamaecyparis pisifera and Chamaecyparis thyoides, at up to 30 m tall or more, belie the Greek etymology of the generic name as “dwarf cypresses”, and Chamaecyparis formosensis and Chamaecyparis lawsoniana at up to 65 m or more are truly gigantic. The genus has long been considered close to Cupressus, and many authors into the middle of the 20th century included these species in that genus. Since then, certain species, like Cupressus funebris, with its flattened sprays of branchlets and relatively small cones, have been assigned fairly indiscriminately to either genus. The apparent close relationship was also emphasized by hybridization between various species of Cupressus and the species usually known as Chamaecyparis nootkatensis, the Alaska yellow cedar, to form the hybrid (notho-) genus x Cupessocyparis. However, the Alaska yellow cedar has long been recognized as anomalous within Chamaecyparis, with its four-scaled seed cones that take 2 years to mature and a leaf and heartwood chemistry that is closer to Cupressus than to the other relatively uniform species that are assigned to Chamaecyparis. DNA sequences strongly support a close alliance of the Alaska yellow cedar with Cupressus, as Cupressus nootkatensis, but show that the other Chamaecyparis species are not particularly closely related to Cupressus. Instead, Chamaecyparis is very close to Fokienia, which has similar cones but more flattened foliage sprays with broader lateral leaves.
The earliest known fossils of Chamaecyparis were recorded from the late Cretaceous of Vancouver Island, Canada, and antedate the Paleocene occurrences of the earliest known Fokienia. These fossils often have branchlets arising from both members of a pair of lateral leaves, a trait no longer found in Chamaecyparis and now confined to the southern hemisphere incense cedars (Libocedrus and related genera).
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.