Cupressaceae description

Phylogenetic tree for the Cupressaceae derived by analysis of the plastid gene rbcL. Lineages in green represent genera formerly assigned to the Taxodiaceae; those in red represent outgroup comparison. Redrawn from (6).

Cupressaceae Rich. ex Bartling 1830

Common names:

Cypress family, HINOKI KA [Japanese],

[Chinese].

Taxonomic notes:

Twenty-nine (many monotypic) genera and 141 species. Syn: Cupressoideae Rich. ex Sweet 1826; Cupresseae Rich. ex Dumort. 1827; Cunninghamieae Zucc. ex Endl. 1842 (5).

The Cupressaceae are found in the fossil record since the Jurassic. The family was formerly divided between Cupressaceae sensu stricto (genera with leaves opposite in four ranks or whorled) and Taxodiaceae (leaves mostly alternate). Foliage characters, however, are seldom used as grounds for discriminating between families. All genera treated here have seed cones in which the bract-scale complexes are fused for most of their common length, the 1-20 ovules are erect (but may invert with maturity), and the paired seed wings, if present, are derived from the seed coat (3, 4). Recent study of plastid (rbcL) DNA sequences has further confirmed the close relationship between the Cupressaceae s.str. and the genera formerly assigned to the Taxodiaceae, finding that most Taxodiaceous genera diverge first, while the Cupressaceae s.str. are derived within the Taxodiaceous genera. The principal exception involves the genus Sciadopitys, which was found to be completely unlike the Cupressaceae, and is now usually treated in the separate monotypic family Sciadopityaceae (6, 7).

Description:

Trees or shrubs, generally resinous and aromatic, monoecious (usually dioecious in Juniperus). Bark fibrous and furrowed (smooth or exfoliating in plates in some Cupressus and Juniperus species). Lateral branches well developed, similar to leading shoots, twigs terete, angled, or flattened dorsiventrally (with structurally distinct lower and upper surfaces in Thuja, Calocedrus, Thujopsis, Fokienia, Libocedrus, Papuacedrus, and to a lesser extent in some other genera), densely clothed by scalelike leaves or by decurrent leaf bases; longest internodes to 1 cm; buds undifferentiated and inconspicuous (except in Sequoia, Metasequoia, Cunninghamia and Juniperus sects. Juniperus and Caryocedrus). Roots fibrous to woody (bearing aboveground"knees" in Taxodium). Leaves simple, usually persisting 3-5(-12) years and shed with lateral shoots (cladoptosic) (shed annually in Taxodium, Glyptostrobus and Metasequoia; leaves with an abscision zone and shed individually in Juniperus Sects. Juniperus and Caryocedrus), alternate and spirally arranged but sometimes twisted so as to appear 2-ranked, or opposite in 4 ranks, or whorled, deltate-scalelike to linear, decurrent, sessile or petiolate; adult leaves appressed or spreading, often differing between lateral and leading shoots (twigs heterophyllous), sometimes strongly dimorphic on each twig (in Thuja, Thujopsis, Fokienia, Libocedrus, Papuacedrus and Calocedrus, and weakly so in some other genera) with lateral scale-leaf pairs conspicuously keeled; juvenile leaves linear, flattened, spreading; often with solitary abaxial resin gland; resin canal present. Pollen cones maturing and shed annually, solitary, terminal (rarely in clusters of 2-5, or to 20 or more in Cunninghamia; axillary in Cryptomeria and Juniperus Sects. Juniperus and Caryocedrus; in terminal panicles in Taxodium and Metasequoia), simple, spheric to oblong; sporophylls overlapping, bearing 2-10 abaxial microsporangia (pollen sacs); pollen spheric, not winged. Seed cones maturing in 1-2 seasons, shed with short shoots or persisting indefinitely on long-lived axes (shattering at maturity in Taxodium), compound, solitary, terminal (rarely in clusters of 2-5, or up to 100 or more in Widdringtonia; axillary in Juniperus Sects. Juniperus and Caryocedrus); scales overlapping or abutting, fused to subtending bracts with only bract apex sometimes free; each scale-bract complex peltate, oblong or cuneate, at maturity woody or fleshy, with 1-20 erect (inverted with age in Athrotaxis, Cunninghamia, Glyptostrobus, Taiwania, Metasequoia, Sequoia and Sequoiadendron), adaxial ovules. Seeds 1-20 per scale, not winged or with 2-3 symmetric or asymmetric wings; aril lacking; cotyledons 2-5 (to 9 in Taxodium) (3, 9).

Range:

It is the most widely distributed of all gymnosperm families, occurring in diverse habitats on all continents except Antarctica, but all genera other than Juniperus show strongly relictual distributions, with a large number of localised, rare and endangered taxa. Most of the generic diversity is in the southern hemisphere, but the largest genus, Juniperus, is chiefly north-temperate (1, 2).

Big Tree:

Sequoiadendron giganteum, also called "Big tree".

Oldest:

Fitzroya cupressoides, with Sequoiadendron giganteum a close second. Both are known to live well over 3,000 years.

Dendrochronology:

Although the Pinaceae continue to account for the majority of dendrochronological work, a great deal has nonetheless been done with the Cupressaceae, particularly in the genera Fitzroya, Juniperus, Sequoiadendron, and Thuja.

Ethnobotany:

The heartwood of many species of Cupressaceae is resistant to termite damage and fungal decay, and therefore it is widely used in contact with soil [e.g., for fenceposts]. Frank Lloyd Wright preferred Taxodium as a siding for wooden residences, while Sequoia is preferred for lawn furniture throughout the vast suburbs of California. The premier coffin wood of China, Cunninghamia lanceolata, is another member of the family, and Chamaecyparis wood is in similar demand in Japan. Many genera are incorrectly called cedars because their heartwood is as aromatic as that of the true cedars, Cedrus (Pinaceae). Wooden pencils are made from incense-cedar (Calocedrus decurrens) and eastern redcedar (Juniperus virginiana), which is also used for lining"cedar" chests. Wood from species of redcedar (Thuja) is used for roofing shingles and for house siding.

Many Cupressaceae are treated with very high regard by traditional societies. In Japan, Cryptomeria japonica is the national tree, and of the 'five sacred trees of Kiso', four are in this family (Chamaecyparis obtusa, Ch. pisifera, Thuja standishii, Thujopsis dolabrata). Thuja plicata is highly revered among the tribes of the Northwest Coast of North America, who made their houses, canoes, baskets, boxes and even clothing from its bark, wood and roots, while Sequoia and Sequoiadendron have inspired a deep sense of reverence among people from western cultures ever since their discovery.

The Cupressaceae are also the most important conifer family in modern horticulture Several species of Chamaecyparis, Cupressus and Juniperus are of major importance in horticultural trade, accounting for about 99.9% of all conifers sold for garden planting in Britain; many thousands of cultivars have been named.

Remarks:

Pollination usually occurs in late winter or spring but may occur anytime from late summer to early winter for some species of Juniperus. Seed maturation occurs in late summer or autumn. Many species of Actinostrobus, Callitris, Cupressus, Neocallitropsis, Sequoiadendron and Widdringtonia have serotinous cones that remain closed for many years, some opening only after exposure to fire (3).

A majority of genera are monotypic and most others display disjunct or relictual distributions, even though individual species may be widely distributed. Only bird-dispersed Juniperus is species rich, with a wide, nearly continuous Northern Hemisphere distribution. Because of their uniformity, seedlings and juvenile specimens may not be determinable to genus (3). Foliage of cultivars may deviate greatly from forms found in wild plants; one, cv. 'Sanderi', defied correct identification for 84 years until 1978 when chemical analysis discovered its generic and specific identity as a juvenile-foliage cultivar of Platycladus orientalis; it had previously been placed under five other genera (including one Shishinderia created for it alone!) by various authors (8).

Although no members of the family attain dominance over immense geographic spans as do some species of the Pinaceae in the boreal forests, they can achieve considerable local and regional prominence. Examples include Sequoia sempervirens along the coast of northern California, several species of Juniperus in central Eurasia, the southwestern United States and Mexico, and baldcypress (Taxodium distichum) in deep swamps of the southeastern United States. Their ranges and regions of dominance were considerably greater during the early Tertiary (3).

Citations:

(1) Silba 1986.
(2) Van Royen 1979.
(3) Watson, F.D. & J.E. Eckenwalder at the Flora of North America web page.
(4) Eckenwalder, J.E. 1976. Re-evaluation of Cupressaceae and Taxodiaceae: A proposed merger. Madroño 23:237-256.
(5) E-mail communication from James L. Reveal, 31-Dec-1998. (6) Brunsfeld, Steven J., Pamela E. Soltis, Douglas E. Soltis, Paul A. Gedek, Christopher J. Quinn, Darren D. Strenge and Tom A. Ranker. 1994. Phylogenetic relationships among the genera of Taxodiaceae and Cupressaceae: evidence from rbcL sequences. Systematic Botany 19(2): 253-262.
(7) Farjon 1998.
(8) L.J. Gough & H.J. Welch. 1978. Bot. J. Linn. Soc. 77: 217-221.
(9) Information contributed by M.P. Frankis, 16-Feb-1999.