Cupressaceae
Cypress Family
Order: Pinales
Phylogenetic Position: Gymnosperms
Family Overview
The Cupressaceae, commonly known as the cypress family, is a diverse family of coniferous trees and shrubs that includes approximately 140-160 species in about 30 genera. This family has a nearly worldwide distribution, with members found on all continents except Antarctica, though they are most diverse in the Northern Hemisphere.
Members of this family range from towering trees to low-growing shrubs and include some of the world's most iconic conifers, such as cypresses, junipers, redwoods, and cedars. They are characterized by their scale-like or needle-like leaves, woody cones, and often aromatic foliage due to resin glands.
The Cupressaceae is of significant ecological importance, with many species forming dominant components of various forest ecosystems. The family is also economically valuable, providing timber, essential oils, and ornamental trees. It includes some of the world's oldest and largest living organisms, such as the giant sequoia and coast redwood, as well as the oldest known individual tree, a Great Basin bristlecone pine.
Botanical Characteristics
Growth Form
Evergreen trees or shrubs, ranging from prostrate ground covers to the world's tallest trees. Growth habits include columnar, pyramidal, spreading, or weeping forms. Many species are long-lived, with some individuals surviving for thousands of years.
Leaves
Leaves are typically scale-like and appressed to the stem in mature plants, though some genera have needle-like leaves (e.g., Juniperus) or both types depending on age or position. Leaves are usually arranged in opposite pairs or whorls of three, often overlapping like roof shingles. Many species have resin glands on the leaves that release aromatic compounds when crushed.
Stems
Stems are woody with distinctive bark that varies by genus from fibrous and shredding (e.g., Juniperus) to thick and furrowed (e.g., Sequoiadendron). Branching patterns are often distinctive, with ultimate branches sometimes arranged in flattened sprays (e.g., Thuja).
Reproductive Structures
As gymnosperms, Cupressaceae do not produce flowers but instead bear separate male and female cones, sometimes on the same plant (monoecious) or on separate plants (dioecious). Male cones are small, terminal or axillary structures that release pollen. Female cones are typically woody with scales arranged in opposite pairs or whorls, maturing in 1-3 years depending on the genus. Some genera (e.g., Juniperus) produce fleshy, berry-like cones with fused scales.
Seeds
Seeds are typically small to medium-sized, often winged for wind dispersal, though wingless in some genera. They are borne on the cone scales, not enclosed in an ovary as in flowering plants. The number of seeds per cone scale varies by genus. In Juniperus, seeds are enclosed in fleshy, berry-like cones adapted for animal dispersal.
Specialized Features
Many members contain terpenoid compounds that give them distinctive aromas and provide resistance to decay and insect attack. Several genera have specialized adaptations to fire, including thick, insulating bark (Sequoiadendron) or serotinous cones that open after fire (some Cupressus species). Some species can reproduce vegetatively through layering or sprouting from the base after damage.
Field Identification
Primary Features
- Leaf arrangement and type: Scale-like leaves arranged in opposite pairs or whorls of three, often overlapping (some genera have needle-like leaves).
- Cone structure: Woody cones with scales arranged in opposite pairs or whorls (or fleshy, berry-like cones in Juniperus).
- Aromatic foliage: Many species release distinctive aromas when foliage is crushed.
- Evergreen habit: All members retain their leaves year-round.
- Branching pattern: Often distinctive, with some genera having flattened sprays of ultimate branches.
Secondary Features
- Bark characteristics: Varies by genus from fibrous and shredding to thick and furrowed.
- Resin presence: Many species exude resin when bark or wood is injured.
- Growth form: Distinctive silhouettes range from narrowly columnar to broadly spreading.
- Cone maturation time: Varies by genus from 1-3 years.
- Seed characteristics: Presence or absence of wings, number per cone scale.
Seasonal Identification Tips
Spring: New growth is often lighter in color and softer in texture. Male cones release pollen, sometimes creating visible clouds of yellow pollen.
Summer: Female cones begin development, though they may not be conspicuous in their first year.
Fall/Winter: Mature cones are most visible, with some opening to release seeds. The evergreen nature of these plants makes them particularly conspicuous in winter landscapes where deciduous trees have lost their leaves.
Potential Confusion Points
- Pinaceae (Pine family): Generally has needle-like leaves in bundles or singly, and cones with spirally arranged scales rather than opposite or whorled scales.
- Taxaceae (Yew family): Has flattened, linear leaves arranged spirally and produces single seeds surrounded by a fleshy aril rather than true cones.
- Podocarpaceae: Has different cone structure with usually only one or few seeds per cone, often with fleshy receptacles.
Notable Examples
Cupressus (True Cypresses)
Trees with scale-like leaves arranged in opposite pairs, forming flattened or quadrangular branchlets. Cones are woody and globose to oblong, with peltate scales that fit tightly together before opening at maturity. Native to North America, Mediterranean region, and Asia.
Ecological/Economic Importance: Many species are important timber trees and widely planted as ornamentals. Some species are adapted to fire-prone environments. The Mediterranean cypress (C. sempervirens) has cultural significance in many regions and is often associated with cemeteries and formal gardens.
Juniperus (Junipers)
Trees or shrubs with either scale-like or needle-like leaves (sometimes both on the same plant). Dioecious (separate male and female plants) in most species. Female cones are distinctive, becoming fleshy and berry-like (technically a galbulus) at maturity, often blue or reddish in color.
Ecological/Economic Importance: Berries are used to flavor gin and other spirits. Wood is aromatic and resistant to decay, used for fence posts and closet linings. Many species are important in arid ecosystems, providing food and shelter for wildlife. Some are invasive in grassland ecosystems.
Sequoia (Coast Redwood)
Massive trees with fibrous, reddish bark and linear to awl-shaped leaves arranged spirally but appearing in two ranks. Cones are small and woody with peltate scales. Native to coastal California and southwestern Oregon.
Ecological/Economic Importance: Includes the world's tallest trees, reaching over 115 meters. Forms unique forest ecosystems along the Pacific coast. Valuable timber species with decay-resistant wood. Important for carbon sequestration and as tourist attractions in protected areas.
Sequoiadendron (Giant Sequoia)
Massive trees with fibrous, reddish-brown bark and awl-shaped leaves arranged spirally around the shoots. Cones are woody and oval, taking two years to mature. Native to the western Sierra Nevada mountains of California.
Ecological/Economic Importance: Includes the world's largest trees by volume. Extremely long-lived, with some individuals over 3,000 years old. Adapted to periodic fire with thick, insulating bark. Important tourist attractions and symbols of conservation.
Thuja (Arborvitae)
Trees or large shrubs with scale-like leaves arranged in flattened sprays. Cones are small, elongated, and woody with overlapping scales. Native to North America and eastern Asia.
Ecological/Economic Importance: Widely used as ornamental plants, particularly for hedges and screens. Wood is lightweight but decay-resistant, used for shingles, posts, and canoes (by indigenous peoples). Some species have been used medicinally.
Chamaecyparis (False Cypress)
Trees with scale-like leaves arranged in flattened sprays. Cones are small, globose, and woody with peltate scales, maturing in one year. Native to North America, Japan, and Taiwan.
Ecological/Economic Importance: Valuable timber trees, particularly in Japan where the wood is prized for construction of temples and baths. Many cultivars are popular ornamental plants. Some species form unique forest ecosystems in their native ranges.
Phylogenetic Position and Evolution
The Cupressaceae is one of several families within the conifers (order Pinales), which are gymnosperms—seed plants that do not produce flowers or fruits. Modern molecular and morphological studies have expanded the traditional concept of Cupressaceae to include the former family Taxodiaceae (redwoods and relatives).
Evolutionary Significance
- Ancient lineage: The family has a fossil record extending back to the Jurassic period, over 150 million years ago.
- Cone evolution: Shows evolutionary trends in cone structure, from the more primitive many-seeded cones of Sequoia to the reduced, fleshy cones of Juniperus.
- Leaf adaptations: Scale-like leaves represent an adaptation to reduce water loss, allowing many species to thrive in arid environments.
- Fire adaptations: Various adaptations to fire regimes have evolved independently in different lineages, including thick bark, serotinous cones, and resprouting ability.
Related Families
Other conifer families include:
- Pinaceae (Pine family)
- Taxaceae (Yew family)
- Podocarpaceae (Podocarp family)
- Araucariaceae (Araucaria family)
- Sciadopityaceae (Umbrella pine family)
These families share the gymnosperm characteristic of producing seeds not enclosed in an ovary, but differ in various aspects of leaf morphology, cone structure, and wood anatomy.
References and Further Reading
Farjon, A. (2005). A Monograph of Cupressaceae and Sciadopitys. Royal Botanic Gardens, Kew.
Earle, C. J. (ed). (2020). The Gymnosperm Database. https://www.conifers.org
Mao, K., Milne, R. I., Zhang, L., Peng, Y., Liu, J., Thomas, P., Mill, R. R., & Renner, S. S. (2012). Distribution of living Cupressaceae reflects the breakup of Pangea. Proceedings of the National Academy of Sciences, 109(20), 7793-7798.
Leslie, A. B., Beaulieu, J. M., Rai, H. S., Crane, P. R., Donoghue, M. J., & Mathews, S. (2012). Hemisphere-scale differences in conifer evolutionary dynamics. Proceedings of the National Academy of Sciences, 109(40), 16217-16221.
Gadek, P. A., Alpers, D. L., Heslewood, M. M., & Quinn, C. J. (2000). Relationships within Cupressaceae sensu lato: a combined morphological and molecular approach. American Journal of Botany, 87(7), 1044-1057.