The families of gymnosperms


L. Watson and M. J. Dallwitz


Pines, Cedars, Firs, Spruces, Larches, Hemlocks.

Vegetative. Evergreen (mostly), or deciduous (in Larix and Pseudolarix); trees (nearly all), or shrubs (a few species of Pinus). Resinous (with resin canals in various parts of the plants, though absent from the secondary wood of Abies, Pseudolarix, Cedrus and Tsuga). Main branches spiral, or whorled, or spiral to whorled. The leafy branchlets not flattened. The vegetative branch systems without conspicuously specialised short-shoots, or including highly specialised, leaf-bearing short-shoots. Mature leaves linear; acicular; paired or in tight clusters on short-shoots, each cluster with a basal sheath of scales, or not clustered (all are borne singly in Abies, Picea, Pseudotsuga and Tsuga, while in Pinus they are all paired or clustered on highly contracted short-shoots, and in Cedrus and Larix they are borne singly on leading long-shoots as well as in clusters on the short-shoots); alternate (or in pseudo-whorls). Longitudinal resin canals present in the leaves (mostly), or absent from the leaves (e.g., some Picea species?); 2 per leaf, these lateral (marginal or “median”), or in a horizontal row, or in a peripheral ring, or in an abaxial arc (rarely), or in an adaxial arc.

Reproductive organization. Monoecious. The ovules borne in female cones (which are confined to mature branches). The female cones woody. The seed-cone scales spirally arranged; persistent, or deciduous, the cones disintegrating at maturity (in Abies, the cone scales are shed, but the axis remains attached); woody. The ovules borne proximal-adaxially on the seed-cone scales. The bract-scales more or less free of the seed-cone scales in mature cones. The seed-cone scales 2 ovuled. The ovules anatropous; 1 integumented.

The crowded male cones, which take the place of short-shoots, bear spirally arranged microsporophylls each two abaxial pollen-sacs dehiscing via a longitudinal slit. The pollen grains have two prothallial cells. Pollen-sacs 2 per microsporophyll. Pollen with air bladders (e.g., Pinus), or without air bladders (e.g., Larix). Pollination anemophilous, and in genera with pollen grains equipped with air bladders (e.g., Pinus), it involves a “liquid drop” mechanism, the grain being drawn into contact with the nucellus as it floats in receding micropylar fluid.

Seeds and seedlings. Seeds winged. Cotyledons (3–)4(–15).

Wood anatomy. Growth rings distinct. Heartwood present and distinctively coloured (brown, reddish or yellow), or present but not distinctively coloured, or absent (whitish, creamy or grey). Latewood not conspicuous, or conspicuous. Wood with a distinct odour, or without distinct odour; with a distinct taste, or without distinct taste; not greasy; without dimpled grain. Tracheids with opposite and multiseriate bordered pits, or with neither alternate nor opposite bordered pits (then the pitting uniseriate); without callitroid pit-border thickenings. Margins of the tori scalloped, or not scalloped. Torus extensions conspicuously present (in Tsuga spp.), or absent (mostly). Earlywood tracheids without spiral thickenings. Axial parenchyma present, or present to absent (e.g., Larix), or absent (e.g., Picea, Pinus). Axial parenchyma when present, scarce. Axial parenchyma not zonate. Axial parenchyma with nodular thickenings or bead-like on the transverse or end-walls, or without nodular thickenings on the transverse or end-walls. Rays exclusively uniseriate, or not exclusively uniseriate (then 1–2 or 1–5 cells wide). Ray tracheids regularly present, or absent or very infrequent. Ray tracheids when present, dentate, or not dentate. Earlywood ray cells with horizontal walls thinner than those of the adjacent vertical tracheids above and below the ray, or with walls similar in thickness to those of adjacent vertical tracheids. Latewood ray cells with unpitted horizontal walls, or with pitted horizontal walls. The pitting when present, strong, or weak. Ray cells exhibiting indentures at the corners, or without indentures; exhibiting nodular or bead-like thickenings on their end walls, or without nodular thickenings on their end walls. Ray tissue exhibiting crystals, or without crystals. Earlywood cross-field pits 1(-3), large and simple (or nearly so), or piceoid, or piceoid and cupressoid, or taxodioid, or piceoid, cupressoid, and taxodioid (Cedrus), or 1–6 pinoid. Normal vertical resin ducts present (e.g., Larix, Picea, Pinus), or absent (Abies). The normal resin ducts with at least some thick-walled epithelial cells, or with only thin-walled epithelial cells; with 7–12 epithelial cells.

Geography, cytology. Frigid zone to tropical; Northern hemisphere, south to Sumatra, Java, Central America and West Indies.

Basic chomosome number, n = 12, or 13 (Pseudotsuga only).

Taxonomy. 232 species; Abies, Cathaya, Cedrus, Keteleeria, Larix, Nothotsuga, Picea, Pinus, Pseudolarix, Pseudotsuga, Tsuga. Order Coniferales.

Miscellaneous. • Pinus sylvestris: techncal details (Le Maout & Decaisne). • Pinaceae: technical details (Sporne). • Cone-scale interpretation: Abies and Keteleeria (Florin). • Cone-scale interpretation: Pinus pinaster (Florin). • Abies alba and Abies grandis (Dallimore and Jackson). • Abies nordmanniana and Abies procera (Dallimore and Jackson). • Picea abies and Picea sitchensis (Dallimore and Jackson). • Abies amabilis (Dallimore and Jackson). • Abies cilicica and Abies concolor (Dallimore and Jackson). • Abies delavayi and Abies firma (Dallimore and Jackson). • Abies grandis and Abies homolepis (Dallimore and Jackson). • Abies koreana and Abies magnifica (Dallimore and Jackson). • Abies numidica and Abies pindrow var. brevifolia (Dallimore and Jackson). • Abies pinsapo and Abies spectabilis (Dallimore and Jackson). • Abies cephalonica, A. veitchii, and A. venusta (Dallimore and Jackson). • Picea omorika (Dallimore and Jackson). • Picea breweriana and P. omorika (Chittenden). • Cedrus atlantica, C. deodara and C. libani (Dallimore and Jackson). • Pinus sylvestris, Pinus strobus and Pinus wallichiana (Dallimore and Jackson). • Pinus heldreichii var. leucodermis, Pinus mugo and Pinus nigra (Dallimore and Jackson). • Pinus peuce, pinaster and Pinus pinea (Dallimore and Jackson). • Pinus radiata and P. thunbergii (Chittenden). • Pinus flexilis and P. bungeana (Chittenden). • Keteleeria fortunei and Tsuga canadensis (Chittenden). • Keteleeria davidiana (Dallimore and Jackson). • Larix decidua and Pseudolarix amabilis (Dallimore and Jackson). • Abies fargesii and Pseudolarix amabilis (Chittenden). • Tsuga caroliniana and T. chinensis (Dallimore and Jackson). • Tsuga diversifolia and T. dumosa (Dallimore and Jackson). • Tsuga heterophylla and T. canadensis (Dallimore and Jackson). • Wood anatomy: Abies alba and Abies grandis. • Wood anatomy: Larix decidua, Larix laricina and Larix occidentalis. • Wood anatomy: Pinus contorta, Pinus monticola and Pinus palustris. • Wood anatomy: Pinus halepensis and Pinus sylvestris. • Wood anatomy: Cedrus brevifolia. • Wood anatomy: Pseudotsuga taxiflia. • Wood anatomy: Picea abies and Picea sitchensis.

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2008 onwards. The families of gymnosperms. Version: 9th April 2015.’.