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Cypress, Linnaeus  1753

Cupressus - Cypress description


Evergreen trees or tall shrubs with a single or multiple trunks. Bark fibrous, usually furrowed and peeling in vertical strips but sometimes flaking to leave a smooth, mottled surface. Crown dense, mostly conical to egg-shaped, but ranging from stiffly narrowly columnar to picturesquely broadly flat-topped or weeping. Shoot system weakly differentiated into main axes and side shoots (branchlets), usually branching in three dimensions, sometimes emerging alternately from lateral leaves on either side of the main twigs to from lateral leaves on either side of the main twigs to form flattened, fernlike sprays, the branchlets cylindrical or four-angled. Resting buds unspecialized, consisting solely of arrested immature foliage leaves. Seedling leaves in alternating quartets, needlelike, standing out from and well spaced on the stem, with one or two bands of stomates above and beneath, soon replaced by adult branchlets. Adult leaves in alternating, similar pairs (not as distinguishable lateral and facial pairs). Leaves of each pair scalelike, closely enclosing the twig, with the tip either pressed against it or pointing outward, sometimes with a prominent resin gland on the surface.

Plants monoecious. Pollen cones numerous, single at the tips of short branchlets, spherical to oblong. Pollen scales in 3-8(-12) alternating pairs, each scale with two to six pollen sacs. Pollen grains small (20-35 µm in diameter), spherical, minutely and irregularly bumpy, with a small, circular germination pore. Seed cones single or clustered at the tips of short side branchlets, spherical or oblong, woody, maturing in two seasons and then opening or remaining closed many years or until opened by fire. Cones with three to seven alternating pairs of centrally stalked, roughly hexagonal seed scales, or with two basally attached pairs, the uppermost pair sometimes united. Seeds 2-20 per seed scale, irregularly angular, often with a prominent attachment scar, variably narrowly two-winged, the wings derived from the seed coat. Cotyledons two (Cupressus nootkatensis and Old World species except Cupressus torulosa) or three to six (Cupressus torulosa and New World species except Cupressus nootkatensis), each with one vein. Chromosome base number x = 11.

Wood faintly to moderately fragrant, light to medium weight, soft to fairly hard, often brittle, sometimes extremely decay resistant. Sapwood pale, generally whitish and giving way gradually to darker, bright yellow, yellowish brown, pinkish brown or reddish brown heartwood, sometimes speckled or streaked. Grain generally even and fine, with distinct but sometimes inconspicuous growth rings marked by a gradual transition to much smaller and slightly thicker walled latewood tracheids. Without resin canals but with fairly numerous individual resin parenchyma cells scattered through the growth increment or somewhat concentrated in variously positioned open rings.

Stomates in patches, primarily on hidden and protected surfaces of the leaves. Each stomate tucked in beneath and partly hidden by the four to surrounding subsidiary cells, which usually carry a steep Florin ring as well as additional round to elongate papillae, which may also be found on other cells of the epidermis. Leaf cross section with a single-stranded midvein flanked by short wings of transfusion tissue. Resin canals up to three in number, lying just inside the epidermis in the attached leaf base but often not extending into the free portion. Photosynthetic tissue with a well-developed palisade layer beneath the epidermis and the very thin hypodermis on the outer face (developmentally the underside) ot the leaf. Looser spongy mesophyll with very large air spaces making up the remaining photosynthetic tissue and most of the leaf volume, which usually lacks additional strengthening cells.

Seventeen species in western North America from Alaska south to Guatemala, the Mediterranean region, and the Himalayan region to southern China.

Cupressus is the classical Latin name for Mediterranean cypress (Cupressus sempervirens) and similar also to the ancient Greek equivalent (kyparissos), which underlies the derivation of Chamaecyparis. The island of Cyprus may be named for its population of Cupressus sempervirens (or for its copper deposits), and this species has been cultivated for millennia in the Mediterranean Sea basin. Several other species are also in general cultivation and have given rise to a broad spectrum of cultivars. Cultivar selection has emphasized primarily habit (compact, columnar, or weeping) and foliage color (blue-green, golden, or variegated).

Although Cupressus is the second most widespread and diverse genus of northern Cupressaceae, there are fewer species than in the vegetatively and (partially) ecologically similar Juniperus, and most of these are very local in distribution. Many are emergents in fire-prone shrublands and most are drought tolerant. Because populations are often well isolated from one another, there is considerable variation from population to population, and species concepts have usually been very narrow, often treating each isolated population as a distinct species. At the other extreme, Cupressus funebris and Cupressus nootkatensis, species with smaller cones than usual and flattened sprays of branchlets, were mistakenly assigned to Chamaecyparis in the past, a genus traditionally considered closely related to Cupressus. In many 19th century works, species of Chamaecyparis were simply included as a section of Cupressus. The weight of evidence today, particularly from leaf chemistry and DNA sequences, shows conclusively that these two genera are not particularly closely related and that Cupressus funebris and Cupressus nootkatensis belong in Cupressus in the broad sense used here. Relationship are actually a little more complicated, and some authors separate Cupressus nootkatensis and Cupressus vietnamensis into their own genus while others suggest that New and Old World species might have to be placed in different genera to avoid merging Juniperus with Cupressus. Evidence for these more unconventional taxonomic arrangements are not presently particularly compelling, so a more traditional approach is taken here.

With the assignment of Cupressus nootkatensis to Cupressus, the hybrid (notho-) genus xCupressocyparis (and its synonym xCuprocyparis),founded to include hybrids between Cupressus nootkatensis and other species of Cupressus, such as the important Leyland cypress, simply becomes a synonym of Cupressus. The reduction of xCupressocyparis to Cupressus and the implausibility of Tsuga mertensiana as a proposed hybrid between Tsuga and Picea leaves only the redwood, Sequoia sempervirens, as a possible example of a hybrid between conifer genera.

As might be expected from a generally dryland genus, the fossil record of Cupressus is sparse. There is a single cone from Miocene deposits in Germany that is safely attributable to the genus as well as many more recent specimens from Pleistocene sediments in coastal California. In addition, the Cretaceous and early Tertiary genus Mesocyparis has some similarity to Cupressus nootkatensis and might be close to Cupressus genetically.




Attribution from: Conifers Garden