Picea

A. Dietrich 1824

Common names

Spruce, épicéa (French), épinette (Canadian French), abete or abies (Italian), fichte (German), gran (Swedish, Norwegian & Danish), jel (Russian), swierk (Polish), smarch (Bulgarian), smrche or omorike (Serbo-croat), yunshan (Chinese), momi (Japanese).

Taxonomic notes

The genus is related most closely to Pinus, but differs markedly even from that. It is a very uniform genus, clearly monophyletic with no aberrant species, so generic segregation has never been suggested (Farjon 1990). There are 33 species treated here, though a careful re-evaluation of the poorly-studied East Asian taxa would probably reduce this number (Farjon 1990, Sigurgeirsson and Szmidt 1993). Classification within the genus is problematic, and no fully satisfactory phylogeny has yet been worked out despite numerous attempts (Wright 1955, Bobrov 1970, Liu 1982, Aldén 1987, Page and Hollands 1987, Rushforth 1987, Schmidt 1989, Farjon 1990, Frankis 1992, Sigurgeirsson and Szmidt 1993). Extensive hybrid introgression and gene exchange between a number of species complicates the research; few spruces have well-established barriers to hybridisation.

Description

Evergreen trees; crown broadly conic to spirelike, 20-60 (-90) m tall; leading shoot erect. Bark gray to reddish brown, thin and scaly (with thin plates), sometimes with resin blisters, becoming relatively thick and furrowed with age. Branches whorled with strong nodal pseudowhorls and additional scattered weaker internodal branches; short (spur) shoots absent; twigs roughened by persistent leaf bases (pulvini). Buds ovoid, apex rounded to acute, sometimes resinous. Leaves borne singly, spreading radially from twigs, usually somewhat forward-pointing and often upswept, persisting to 10 years, mostly 4-angled and square in cross section (to triangular or ± flattened), mostly rigid, sessile on peglike base; base decurrent, persistent after leaves shed, sheath absent; apex usually sharp-pointed, sometimes bluntly acute; resin canals 1-2. Cones borne on year-old twigs. Pollen cones single or grouped, axillary, oblong, yellow to purple; pollen shed in spring. Seed cones green to purple, maturing pale to dark brown in autumn, 4-8 months from pollination, usually shed at maturity, borne mostly on upper branches, pendent, ovoid to cylindric, sessile or terminal on leafy branchlets and thus appearing ± stalked; scales persistent, elliptic to fan-shaped, thin, lacking apophysis and umbo; bracts included. Seeds winged; cotyledons 5-10 (- l5). x =12 (Taylor 1993, M.P. Frankis e-mail 4-Jan-2002).

Range

Restricted to subtropical high altitude , temperate, and boreal regions of the northern hemisphere. Confined to mountains in the south, its principal realm is the boreal forest, where it provides the dominant species across vast tracts of Scandinavia, Russia, Alaska, and Canada. It has its high est species diversity in the mountains of south and west China and Japan. The southernmost extension of the genus (P. morrisonicola) is on Taiwan, just south of the Tropic of Cancer at 23°N; in the New World Picea extends (via P. chihuahuana and P. martinezii) almost as far, but does not quite reach the Tropic (Taylor et al. 1994).

Big tree

See Picea sitchensis.

Oldest

Maximum attainable ages are known for relatively few species. Working by analogy from other members of the Pinaceae, the greatest ages are normally found on sites that provide extreme physiological stress due to drought, cold, or darkness (i.e. deep shade). Picea avoids arid climates, but it encounters cold stress and some drought stress at alpine timberline sites. An age of 852 years recorded for P. engelmannii on such a site is evidently the current record for the genus.

Dendrochronology

Ethnobotany

The genus is of major economic importance for timber, the most important species being P. sitchensis and P. abies. Several species are commonly used for Christmas trees, most often P. abies but also P. omorika and P. mariana (surely one of the homeliest conifers).

Observations

Remarks

Name from the Roman pix, pitch (Weber 1987); or from picis, the name of a pitchy pine (Taylor 1993).

Citations

See also

Roche, L. 1969. A genecological study of the genus Picea and seedlings grown in a nursery. New Phytologist 68: 505-554.

Taylor, R.J. and T.F. Patterson. 1980. Biosystematics of Mexican spruce species and populations. Taxon 29: 421-469.