CONIFERS OFTEN USED FOR BONSAI IN NORTH AMERICA We have consulted The Plant List and some regional floras to verify correct scientific names.

For detailed information on individual conifer species, including photographs, we recommend that you go to conifers.org.

Trees are evergreen unless otherwise noted. Species that are native in North America are green.

COMMON NAME(s) LATIN NAME (Genus) COMMENTS

Firs Abies Firs have flattened needles arranged in more or less flattened rows along opposite sides of twigs. Mature seed cones are upright, appearing somewhat like fat candles on the uppermost tree branches. When the cones are mature, they disintegrate. Firs are widespread inhabitants of cooler areas of the North Temperate Zone. They prefer cool to cold, acid, continually moist soil and high light intensity. These requirements mean that they rarely are successful long-term bonsai subjects.

True Cedars Cedrus Depending on which source you consult, there are three to five species in this genus. Atlas Cedar, Cedrus atlantica, is the only species usually used for bonsai, and plants with silvery-bluish needles (‘Glauca’ or “Blue Atlas”) are favored. This species is native in the Atlas Mountains of Morocco and Algeria.

False Cypresses Chamaecyparis Chamaecyparis obtusa ‘Nana’, Dwarf Hinoki Cypress, is a selection of Hinoki Cypress which is native to Japan and Taiwan. It is a common bonsai subject. Chamaecyparis thyoides, Atlantic White Cedar, is sometimes used for bonsai. In nature, it grows in acid Southeastern acidic coastal plain bogs. Sawara Cypress, C. pisifera, is a Japanese species occasionally used for bonsai. Members of this genus have flattened, scale-leaves.

Japanese Cedar Cryptomeria Cryptomeria japonica is the only species in the genus. It is native to moist mountain forests throughout the main island of Japan (Shikoku). Wild populations in many areas have been become very small, but there are significant areas in northern and western Shikoku where the populations are doing very well. Several dwarf varieties are in propagation; probably the most common one in bonsai culture is ‘Tansu’. Leaves are scale-like.

True Cypresses Cupressus Members of this widespread and diverse genus often occur in scattered, isolated and variable populations, so there isn’t complete agreement about how many species there are. Arizona cypress (Cupressus arizonica), one of the most varia- ble species, is native in southern Arizona and New Mexico and northern Mexico. It is sometimes grown as a bonsai. Cupressus nootkatensis, Alaska Cedar or Alaska Yellow Cypress grows in

moist forests from southeast Alaska to the Cascade Range. It is sometimes collected from wild populations and trained as bonsai. These two species require very different approaches to their culture, and it is difficult to grow them far from their native habitats. There is a tortuous history involving the scientific name for Alaska Cedar, which you can access by following this link. (Note the synonyms there.) A few rare Cupressus species native in California are sometimes grown as bonsai in that region.

Junipers Juniperus Junipers are tough, drought-tolerant conifers that require abundant sunshine. They are very popular bonsai subjects. The most common juniper bonsai are cultivated selections of Chinese Juniper (Juniperus chinensis, especially var. sargentii, var. foemina and ‘San Jose’), Dwarf Japanese Garden Juniper (Juniperus procumbens ‘Nana’) is probably the most commonly used bonsai subject for beginners in North America, but many are soon lost to overwatering and spider mite infestations.

Several native junipers native to the western U.S., including Rocky Mountain Juniper (Juniperus scopulorum), California Juniper (Juniperus californica), Western Juniper (Juniperus occidentalis) and Sierra Juniper (Juniperus grandis) are often grown as bonsai from wild-collected plants in the far west U.S. East of there in semidesert and desert regions, other species (including J. deppeana, Alligator Juniper; J. monosperma, One- seed Juniper; J. osteosperma, Utah Juniper) are favored.

Common juniper, Juniperus communis, native in northern North America, is often used for bonsai in that region. Eastern Red Cedar (Juniperus virginiana) is easily obtained from wild sources in the eastern U.S. and works well as bonsai in group plantings, but is difficult to train into esthetically pleasing designs as a single tree.

Some junipers grown in more humid eastern environments are susceptible to several serious fungal diseases. Hot and dry conditions encourage spider mite infestations on many junipers.

Larches and Tamaracks Larix Members of this genus are deciduous, needle-bearing trees. Most of the needles are on short spur branches. Various species occur on all of the northern continents. Some species’ ranges extend to the limits of tree growth in mountains and the Arctic. The most adaptable species for bonsai is Larix decidua (European Larch), although it is seldom used in North America. The range of Larix laricina (Tamarack) extends from the Mari- time Provinces to the Yukon and central Alaska, southward to Minnesota and northern West Virginia. Its most common habitats are acidic bogs and muskegs where the soil is cool and continually moist, winter temperatures are low and there is more sun than shade. This species is widely used for bonsai.

Larix occidentalis, Western Larch or Western Tamarack naturally grows on mountain slopes in the Cascades, Blue Mountains and central Rockies. It is gaining popularity among bonsai growers in that region. Larix kaempferi, Japanese Larch, native in northeastern China and Japan, is sometimes used for bonsai in eastern North America.

Dawn Redwood Metasequoia Metasequoia glyptostroboides, Dawn Redwood, is the only species, although there are fossils of other species. This deciduous conifer sheds its youngest twigs and needles in the fall. Although it withstands cold weather well, it is best adapted to warm and wet temperate conditions and acid soil. Abundant water is advised during the growing season. It is a popular bonsai subject, but must be pruned and repotted frequently, or it will soon outgrow any container. It is frequently grown as miniature groves and forests. Dawn redwood needles are opposite each other on the twigs, unlike Bald Cypresses (Taxodium) which have alternately-arranged needles.

Spruces Picea Spruces are widespread in cooler parts of the Northern Hemi- sphere. They are common in mountains and northern boreal (spruce-fir) forests. They require cool, moist soil and often are associated with acid soils. They are typically thought of as being shade-intolerant. However, in nature they sometimes exist for many years and grow extremely slowly when supplied with minimal sunlight. Needles are borne singly on twigs.

Almost all spruces have sharp-pointed needles that are 4-angled in cross-section (you can roll the needles between your thumb and forefinger). (Exceptions are Sitka, Brewer and Serbian spruces; their needles are flattened-triangular in cross-section). Unlike hemlocks (Tsuga), the upper tips of spruce trees are erect, not drooping. (Other technical differences between spruces and hemlocks are summarized here.)

Among the most commonly used spruces used for bonsai are the ‘Nidiformis’ and ‘Little Gem’ cultivars of Norway Spruce (Picea abies). Among native species, various forms of White Spruce (Picea glauca) are used frequently. (‘Conica’ is a useful cultivar for bonsai; synonyms include P. albertiana ‘Conica’ and Dwarf Alberta Spruce. Unfortunately, these cultivars are very suscepti- ble to spider mite infestations.). A closely related variety of White Spruce, Black Hills Spruce (Picea glauca var. densata) is a good bonsai subject that is gaining in popularity. Other native species used as bonsai include Red (Picea rubens), Engelmann (Picea engelmannii) , Black (Picea mariana) and Sitka (Picea sitchensis, including its cultivar ‘Papoose’) spruces. Collected Colorado Spruces (Picea pungens) are used as bonsai, mostly in the western U.S, even though the foliage from many populations often is more coarse than most other native spruces. Landscape plantings of Colorado Spruce in the East are almost always attacked by Cytospora Canker, which is incurable.

Because it is difficult to succeed long-term and time-consuming to grow young spruces to maturity in containers, most native spruce bonsai are collected from wild populations. Overall, Picea jezoensis, Ezo Spruce, is probably the most desirable spruce species for bonsai; it has extremely short needles. However, Ezo Spruces are now extremely rare in North America because of well justified import restrictions and the fact that few people in the U.S. are even trying to propagate them.

Pines Pinus Pines are evergreen trees with needles that occur in bundles of 2 to 5 (rarely 1 needle to a bundle). Each bundle of needles is actually a short stem. When it is young and the new needles are immature, the main stem on which the needle bundles occur is called a candle. Most pines prefer acid, well drained soil and abundant sunshine.

Plants native to the Orient commonly used as bonsai include Japanese Black Pine (Pinus thunbergii), Japanese Red Pine (Pinus densiflora) and Japanese White Pine (Pinus parviflora). Mugo (Pinus mugo) and Scots Pine (Pinus sylvestris) are Euro- pean or Eurasian pines often used for bonsai in North America. North American pine species often usedare Ponderosa (Pinus ponderosa), Shore and Lodgepole (Pinus contorta), Jack (Pinus banksiana), Limber (Pinus flexilis), Virginia (Pinus virginiana), Pitch (Pinus rigida), and in the Deep South, Sand Pine (Pinus clausa). Most western North American and some imported pine species when grown in more humid eastern North America are susceptible to very serious needle cast diseases which can be controlled only by heavy fungicide use. Eastern North American pine species are resistant to those diseases.

Douglas Firs Pseudotsuga These comments include information from conifers.org and the Flora of North America. Douglas firs are prominent trees in forests of western North America and eastern Asia. Douglas firs are distinguished from similar conifers by their relatively large terminal buds, flattened leaf scars (which contrast with the small “pegs” left on hemlock and spruce twigs when needles drop off), and their pendulous cones which have bracts (look a bit like snake tongues!) protruding from between the cone scales.

There is general agreement that there are two North American species; one of them has two subspecies. Bigcone Douglas Firs (Pseudotsuga macrocarpa) are native in chaparral and mixed forest in southern interior California. Their cones average more than 9 cm long and 4 cm broad. The other species, Pseudotsuga menziesii, has smaller cones. Trees of its coastal subspecies,

Pseudotsuga menziesii subsp. menziesii, occur mainly at relatively low elevations from southern Alaska to about latitude 35o in the California coast ranges and Sierra Nevada. Pseudotsuga menziesii subsp. glauca, Rocky Mountain or Interior Douglas Fir, grows in the mountains from Alberta to Oaxaca, Mexico. It is progressively rare and threatened by human activity southward. This subspecies is generally more tolerant of heat and drought than the coastal subspecies, and its foliage often has an attractive grayish look.

Douglas Firs are often collected and used for bonsai, mostly in regions near where they were growing naturally.

Bald Cypresses Taxodium There probably always will be differences of opinion about the taxonomy of Bald Cypresses, but as more and more people observe them carefully, botanical opinion has crystallized, though it is not unanimous. And the results are that two species are now recognized. One of the two species has two varieties. Taxodium distichum var. distichum is the familiar Bald Cypress, which grows in swamps of various types from south- ern New Jersey to south Texas. Its alternate needles spread from the twigs, and twigs of the current year spread from older twigs, making the foliage look like a array of delicate green birds’ feathers. Pond Cypress, Taxodium distichum var. imbricatum (or Taxodium ascendens, if you want to call it a species) is more often found in small depressions that hold water part of the year, and typically has a more literati growth form and a less pronounced basal flare than var. distichum. In contrast to var. distichum, the needles of var. imbricatum grow strongly upward along the twigs, and the twigs themselves typically turn strongly upward (=“ascendens”). All young twigs and their needles are deciduous in autumn.

Taxodium mucronatum, Montezuma Cypress, grows in habitats that are not water-limited from the lower Rio Grande to western Guatemala. It differs only slightly from T. distichum; its cones are a bit smaller, it tends to remain evergreen, and does not withstand low temperatures as well. If you consult distribu- tion maps with a sharp eye, you will notice that bald cypresses on the north side of the Rio Grande are called Taxodium distichum, while bald cypresses just across the river in Mexico are called Taxodium mucronatum. That illustrates the somewhat arbitrary distinction between the two species. Another impedi- ment to merging the two species is that ahuehuete (T. mucronatum) is the national tree of Mexico.

All bald cypresses are excellent bonsai subjects. They thrive with abundant water and full sun. During the growing season, you can place their containers in shallow water. Just remember to change the water frequently to get rid of mosquito larvae.

Arborvitaes Thuja This genus has flattened branchlets (they look like they’ve been pressed with an iron) with scale-like leaves. The foliage is similar to, but much coarser than, the foliage of Chamaecyparis. There are two North American species. Northern White Cedar or Arborvitae (Thuja occidentalis) is native in swampy or rocky habitats, usually over alkaline rocks, from eastern Canada west to Manitoba, south in the Appalachians to North Carolina and east Tennessee. When not in swamps, it often grows on shore lines and cliffs. The second species is Western Red Cedar, Thuja plicata. It typically grows temperate mixed coniferous rain forest, from northwest California to southeast Alaska, and in an area of the northern Rockies.

Individuals of both species tend to become contorted and natu- rally dwarfed when growing in extreme environments. Collected trees that show these characteristics are prized for bonsai. Arborvitaes defy classical bonsai styling.

Hemlocks Tsuga There are four native hemlocks in North America. Two of them, Canadian Hemlock (Tsuga canadensis) and Western Hemlock (Tsuga heterophylla) have needles that appear to be arranged in two rows, one row along each side of a twig. Although many people give it a try, Canadian Hemlock is hard to style artistically and difficult to grow long term in a reasonably sized container. These two species are not widely seen as “finished” bonsai.

The two other species are much more interesting. Their twigs grow more stiffly and needles are arranged around the twigs, giving the foliage a more bushy and appealing look. Bonsai practitioners in the Pacific Northwest have found that collected Mountain Hemlocks (Tsuga mertensiana) make outstanding bonsai. This is a tough but exacting species. It grows naturally from Cook Inlet, Alaska to the California Sierras and south from the Columbia Mountains of British Columbia to northern Idaho and extreme western Montana. Its usual habitats are near treeline in mountainous country, which means that it grows close to sea level in Alaska, but in higher, extreme environments going south. Bonsai practitioners outside the Pacific Northwest have little experience with this species. The remaining species, Carolina Hemlock (Tsuga caroliniana), grows naturally only in the Southern Appalachians, from southwestern Virginia to north- east Georgia. Because of its growth form and relative heat and drought tolerance, it probably would be the best native hemlock of all for bonsai, but it is rarely used. Also, unfortunately, wild populations are under dire threat of extinction due to an introduced insect (hemlock woolly adelgid), so wild plants should never be collected. Seeds and tissue culture are possible ways to bring this species into wider use for bonsai.

We have chosen not to include Coastal Redwood (Sequoia) and California Bigtree (Sequoiadendron), because they only succeed in containers within a narrow region, and rarely succeed long-term as bonsai.

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