Pinaceae

Lindley 1836

Common names

Pine family, [Chinese].

Taxonomic notes

Sometimes treated as the sole family of Order Pinales Dumort. 1829. Syn: Abietaceae. There are here treated 11 genera and 232 species.

Pinaceae are known in the fossil record since the Cretaceous. The family originally included all conifers but is now restricted to a clearly monophyletic group united by characters seen in the mature seed cones: bract-scale complexes consisting of well-developed scales that are free from the subtending bracts for most of their length, two inverted ovules on the adaxial face of each scale, and a (usually obvious) seed wing developed from the cone scale (Thieret 1993). Cone and seed characters further serve to discriminate the four subfamilies, as follows (Frankis 1989, Farjon 1990):

Subfamily Pinoideae. Cones with a distinct umbo from 2(3) season growth, scales with a broad base. Seedwing holding the seed in a pair of claws, or adnate; no resin vesicles on the seed. Micropylar fluid (in conelets at pollination) present: Pinus.

Subfamily Piceoideae. Cones without an umbo, scales with a broad base. Seed blackish, loosely held on a cup on the seedwing; no resin vesicles on the seed. Micropylar fluid present: Picea.

Subfamily Laricoideae. Cones without an umbo, scales with a broad base. Seeds whitish, firmly fixed to the seedwing; no resin vesicles on the seed. Micropylar fluid absent: Cathaya, Larix, Pseudotsuga.

Subfamily Abietoideae. Cones without an umbo, scales with a narrow base. Seeds brown, moderately firmly fixed to the seedwing; resin vesicles present on the seed. Micropylar fluid absent: Abies, Cedrus, Keteleeria, Nothotsuga, Pseudolarix, Tsuga.

Description

Tree: Trees, occasionally shrubs, evergreen (annually deciduous in Larix and Pseudolarix), resinous and aromatic, monoecious.
Bark: Smooth to scaly or furrowed.

Branches: Terminal branches distinct from lateral branches in having radial symmetry. Lateral branches well developed and similar to leading (long) shoots, or reduced to well-defined short (spur) shoots (Larix, Pseudolarix, Cedrus) or dwarf shoots (Pinus); twigs terete, sometimes clothed by persistent primary leaves or leaf bases; longest internodes between leaves less than 1 cm; buds conspicuous. Several genera (e.g. Picea, Pinus, Pseudotsuga, Tsuga) produce epicormic branches, and Pinus produces interfascicular branches.

Roots: Fibrous to woody, commonly comprised of woody structural roots that terminate in nonwoody ectomycorrhizal fine roots that are replaced semiannually to annually.

Leaves: Leaves simple, shed singly (whole fascicles shed in Pinus), alternate and spirally arranged but sometimes twisted at the base so as to appear 1- or 2-ranked, or fascicled, linear to needlelike, sessile to short-petiolate; foliage leaves either borne singly (spirally) on long shoots or in tufts (fascicles) on short shoots; juvenile leaves (when present) borne on long shoots; resin canals present. Cotyledons 2-15(-24).

Cones: Seed cones maturing in 1 season (2-3 seasons in Pinus) and shed soon after, or long-persistent, sometimes serotinous (not opening upon maturity but much later: some Pinus, and Picea mariana), compound, axillary, solitary or grouped. Cones generally lateral, but can be terminal in Picea and Tsuga.

Cone scales: Overlapping, free from subtending included or exserted bracts for most of length, spirally arranged, strongly flattened, at maturity relatively thin to strongly thickened and woody (in Pinus), with 2 inverted, adaxial ovules.

Pollen cones: Matured and shed annually, solitary or clustered, axillary, ovoid to ellipsoid or cylindric; sporophylls overlapping, bearing 2 abaxial microsporangia (pollen sacs); pollen spheric, 2-winged, less commonly with wings reduced to frill (in Tsuga sect. Tsuga), or not winged (in Larix and Pseudotsuga).

Seeds: Two per scale, elongate terminal wing partially decurrent on seed body (wing short or rudimentary in some species of Pinus); aril lacking.

Range

The Northern Hemisphere: south to the West Indies, Central America, Japan, China, Indonesia (one species, Pinus merkusii, crosses the equator in Sumatra), the Himalaya, and North Africa. The family is dominant in the vegetation of large regions including (in North America) forests of the boreal and Pacific regions, the western mountains, and the southeastern coastal plain (1). Various species, most commonly Pinus radiata, have been widely introduced for timber production in sub-Saharan Africa, South America, New Zealand and Australia.

Big tree

Pseudotsuga menziesii, with Picea sitchensis a close second.

Oldest

Pinus longaeva.

Dendrochronology

The majority of all dendrochronological research has involved species of the Pinaceae. Very many studies have involved species of Picea and Pinus, fewer but still a great many studies have involved Abies, Larix, Pseudotsuga and Tsuga, and rather few studies have involved the smaller genera.

Ethnobotany

Members of the Pinaceae provide most of the world's softwood timber. They also provide pulpwood, naval stores (e.g., tar, pitch, turpentine, etc.), essential oils, and other forest products. Many species of Pinus produce edible seeds, commonly known by names such as piñon or pignolias. Many species, including most of the genera, are grown as ornamentals and shelter-belt trees and for revegetation.

The genera most commonly seen in cultivation are Abies, Cedrus, Larix, Picea, Pinus, Pseudotsuga, and Tsuga, each of these genera being represented by numerous cultivars. Keteleeria and Pseudolarix are mainly botanical garden subjects. Cathaya and Nothotsuga, the most recently described genera (1958, 1988), are apparently not yet in cultivation in North America (Thieret 1993).

Observations

See the generic and species descriptions.

Remarks

The Pinaceae are by far the most economically and ecologically important gymnosperm family. Without the Pinaceae, the gymnosperms are little more than a botanical curiosity, their dominance largely confined to semiarid regions with their abundant Juniperus. With the Pinaceae, the gymnosperms continue to dominate many of the most widespread vegetation types on earth, including most boreal forests, most temperate and boreal mountain forests, and vast expanses of North American, African, European and Asian semiarid woodlands.

Citations

Frankis, M. P. 1989. Generic inter-relationships in Pinaceae. Notes Roy. Bot. Gard. Edinburgh 45: 527-548.

See also

Burns & Honkala (1990).

Canadian Forestry Service (1983).

Hosie (1969).

Peattie (1950).

This page was co-edited with Michael Frankis, 1999.01.