The families of gymnosperms


L. Watson and M. J. Dallwitz


Cypresses, Incense Cedars, Junipers, Arbor Vitae.

Currently excluding Taxodiaceae.

Vegetative. Evergreen; trees and shrubs (with all their parts opposite and decussate, or whorled). Resinous (exhibiting resin cells - not ducts - in the wood, but with canals in the stem cortex and leaves). The leafy branchlets flattened in one plane (often), or not flattened. Mature leaves dimorphic (Juniperus), or not dimorphic; usually small, scale-like (and decurrent), or linear (sometimes, like the juvenile leaves), or linear and scale-like (in Juniperus); when linear, acicular (Juniperus); not clustered; opposite and decussate, or whorled. Longitudinal resin canals present in the leaves, or absent from the leaves (sometimes?); in Fitzroya, Juniperus, 1 per leaf, this median-abaxial (no information for the rest).

Reproductive organization. Monoecious, or dioecious (e.g., usually so in Juniperus). The reproductive organization not flower-like. The ovules borne in female cones. The female cones woody, or fleshy and berry-like. The seed-cone scales opposite and decussate, or whorled (then the whorls of three or four members); persistent; fleshy (and berry-like, Juniperus), or leathery, or woody. The ovules borne proximal-adaxially on the seed-cone scales. The bract-scales not clearly resolvable from the seed-cone scales (the "ovuliferous scale" vestiges apparently so reduced that the ovules are virtually borne on the bracts). The seed-cone scales 1–2 ovuled (rarely), or 3–20 ovuled. The ovules orthotropus.

Male cone scales opposite, decussate or whorled. Pollen-sacs (2–)3–6 per microsporophyll. Pollen without air bladders. Pollination anemophilous, involving a “liquid drop” mechanism.

Seeds and seedlings. Seeds with no fleshy investment; winged, or wingless. Cotyledons 2 (usually), or 5–6, or 9.

Wood anatomy. Growth rings indistict, or distinct. Heartwood present and distinctively coloured, or present but not distinctively coloured, or absent. Latewood not conspicuous (mostly), or conspicuous (e.g., in Thuya spp.). Wood with a distinct odour, or without distinct odour; with a distinct taste, or without distinct taste; greasy to the touch, or not greasy; without dimpled grain. Tracheids with neither alternate nor opposite bordered pits (uniseriate, except in Thuya); with callitroid pit-border thickenings, or without callitroid pit-border thickenings (mostly). Margins of the tori scalloped (e.g., in Juniperus thurifera and Thuya occidentalis), or not scalloped (mostly). Earlywood tracheids without spiral thickenings. Axial parenchyma present. Axial parenchyma abundant (usually), or scarce. Axial parenchyma zonate, or 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 (commonly), or not exclusively uniseriate (then usually only 1–2 cells wide). Ray tracheids regularly present (e.g., Chamaecyparis nootkatensis), or absent or very infrequent (usually). Ray tracheids when present, 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 (usually). Latewood ray cells with unpitted horizontal walls, or with pitted horizontal walls. The pitting wnen present, strong (Thujopsis), or weak (usually). 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 without crystals. Earlywood cross-field pits cupressoid (mostly), or piceoid and cupressoid (Tetraclinis), or cupressoid and taxodioid (rarely, in Chamaecyparis), or taxodioid (e.g., some Thuja spp., Thujopsis). Normal vertical resin ducts absent.

Geography, cytology. Cosmopolitan.

Basic chomosome number, n = 11.

Taxonomy. S. str., about 115 species; Actinostrobus, Callitris, Calocedrus, Chamaecyparis, Cupressus, Diselma, Fitzroya, Fokienia, Juniperus, Libocedrus, Neocallitropsis, Pilgerodendron, Platycladus, Tetraclinis, Thuja, Thujopsis, Widdringtonia. Order Coniferales.

Comments. Subfamilies proposed by Gadek et al. (2000), with former Taxodiaceae included: Callitroideae Saxton (Callitris, Neocallitropsis, Diselma, Widdringtonia, Libocedrus); Athrotaxidoideae Quinn (Athrotaxis); Cunninghamioideae (Sieb. & Zucc.) Quinn (Cunninghamia); Cupressoideae Rich. ex Sweet (Cupressus, Juniperus, Xanthocyparis, Microbiota, Platycladus, Tetraclinis, Calocedrus, Chamaecyparis, Fokiena, Thuja, Thujopsis); Sequoioideae (Luerss.) Quinn (Sequoia, Sequoiadendron, Metasequoia); Taiwanioideae (Hayata) Quinn (Taiwania); Taxodioideae Endl. ex K. Koch (Taxodium, Glyptostrobus, Cryptomeria).

Miscellaneous. • Actinostrobus pyramidalis: habit, female cones. • Chamaecyparis formosensis and Ch. lawsoniana (Dallimore and Jackson). • Chamaecyparis obtusa and Ch. pisifera (Dallimore and Jackson). • Chamaecyparis thyoides and Xanthocyparis nootkatensis (Dallimore and Jackson). • Cupressus sempervirens (Lindley). • Cephalotacaceae, Cupressaceae, Taxodiaceae: technical details (Sporne). • Cupressus macrocarpa and C. goveniana (Chittenden). • Cupressus funebris and Cupressus goveniana (Dallimore and Jackson). • Cupressus lusitanica and Cupressus macrocarpa (Dallimore and Jackson). • Cupressus sempervirens and Cupressus torulosa (Dallimore and Jackson). • Fitzroya cupressoides (Dallimore and Jackson). • Fokienia hodginsii (Dallimore and Jackson). • Juniperus communis and Juniperus oxycedrus (Dallimore and Jackson). • Juniperus chinensis and Juniperus drupacea (Dallimore and Jackson). • Juniperus excelsa and Juniperus phoenicea (Dallimore and Jackson). • Juniperus rigida and Juniperus sabina (Dallimore and Jackson). • Juniperus thurifera and Juniperus virginiana (Dallimore and Jackson). • Juniperus wallicheana (Dallimore and Jackson). • Juniperus drupacea and J. virginiana (Chittenden). • Thuja orientalis var. filiformis: as T. filiformis Lindl., Bot. Reg. 20 (1842). • Cone-scale interpretations: Callitris, Libocedrus, Tetraclinis, Thujopsis (Florin). • Cone-scale interpretation: Juniperus communis (Florin). • Wood anatomy: Callitris glaucophylla. • Wood anatomy: Calocedrus decurrens. • Wood anatomy: Chamaecyparis pisifera, C. thyoides, and Cupressus macrocarpa. • Wood anatomy: Juniperus virginiana. • Wood anatomy: Thuja occidentalis.

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.’.