Unlike most other plants, conifers do not flower; rather, they grow bracts of tough leaves in a cone-shaped structure or produce fleshy seed cones. These cones hold and protect their seeds until the time is right for dispersal. Most coniferous trees are evergreen, or keep their foliage year-round, but a few are deciduous. Although many types of coniferous trees exist, their varying shapes, colours, growth patterns and especially their leaves offer several identification methods.
Some coniferous trees have needles that grow singly. These include firs (Abies spp.) and spruces (Picea spp.) Firs range from the 30-foot-tall Korean (A. koreana), which has grey-green needles and produces 1-inch-long purple cones, to the balsam fir (A. balsamea), which grows to 80 feet tall and has dark green needles and grey-green cones. Spruces also grow in a range of sizes and shapes, from the 60-foot-tall Norway spruce (P. abies), with its hanging 6-inch-long cones and weeping foliage, to the 30-foot-tall Liakiang (P. likiangensis), which grows to 30 feet tall, produces 3-½-inch-long purple cones and has blue-green, white-striped needles. Other single-needled conifer types include Douglas fir (Pseudotsuga menziesii).
Pine trees (Pinus spp.) grow needles in tight bundles, with two or more needles emerging from the same point. Pines grow in a range of sizes, shapes and colours. The bristlecone (P. aristata) grows to 20 feet tall with a wide, 15-foot spread. This shrubby tree has bundles of short, blue-green needles and produces 4-inch-long, cylindrically shaped cones. The Yunnan pine (P. yunnanensis) grows to 80 feet tall with a conical shape. It produces 6-inch-long bundles of bright green needles and groups of three red-brown cones. Other bundled-needle conifers include larches (Larix spp.).
Some coniferous trees have foliage that overlaps like the scales of a reptile. These include junipers (Juniperous spp.) and arbor vitae (Thuja spp.), both of which produce fleshy seed cones. Junipers range from the 60-foot-tall, 4-foot-wide Chinese juniper (J. chinensis), a columnar tree that has dull green foliage and produces blue-black fruits, to the 40-foot-tall Eastern red cedar (J. virginiana), a slightly weeping tree with grey-green foliage and blue berries. The giant arbor vitae (T. plicata) grows up to 80 feet tall, has green and white foliage and produces tiny upright cones, while the eastern arbor vitae grows to 60 feet tall and has deep green foliage that often turns yellow in the winter.
Linear foliage resembles needles, but is soft and feathery. Yew trees (Taxus spp.) have linear evergreen foliage and produce fleshy seed cones. This coniferous genus includes the English yew (T. baccata), a broad tree that grows to 60 feet tall and has glossy dark green leaves. The Japanese yew (T. cuspidata) grows from 10 to 40 feet tall with a similar or greater spread. It has pale green curved needles. Both produce red seeds.
- Colorado State University Extension; Identifying Conifers; David Whiting, et al.; August 2010
- NC State University; Abies Koreana; Erv Evans
- NC State University; Abies Balsamea; Erv Evans
- NC State University; Taxus Baccatas; Erv Evans
- NC State University; Thuja Occidentalis; Erv Evans
- NC State University; Pinus Aristata; Erv Evans