Biodiversity in the urban forest is incredibly important to resilience and long-term planning (something we’ve written about extensively, here, here, here,  and here, to name just a few). To help designers start thinking about ways to increase diversity, we’re starting a series on some of our favorite species. Many of the species included will be underused. Some may not be underused, but included anyway because they have so many great attributes. Combining a large number of these more common species can still create diverse plant palettes.

Today’s group of species is a tribute to fall: a group of deciduous conifers. 

Deciduous conifers are needle leaved trees that lose their needles in the fall. Most have spectacular fall color, all the more spectacular because of the uniqueness of seeing needles change color. Today I’ll be writing about:

• Larix laricina, Tamarack
• Taxodium distichum, Bald-cypress
• Metasequoia glyptostroboides, Dawn Redwood

Larix laricina, Tamarack

Tamaracks are eye catching in all seasons. In spring, the unusual soft, pinkish female cones (strobili) draw attention, soon followed by the softest looking (and feeling) clusters of green needles in summer. In fall, the golden color of the needles is hard to miss, especially as they often grow in large groups. In winter, beautiful silhouettes of needle-less tamaracks, bearing small brown cones, stand out, still drawing attention to their unique features of being deciduous conifers.

Native to bogs and lakeshore edges in peaty soil in North America, tamaracks grow best in moist, acidic soils in full sun and do not tolerate hot, humid weather south of USDA zone 5. They grow well in large raingardens and other wet or moist sites, and also tolerate upland suburban sites.

Scientific Name	Larix Laricina
Common Name	Tamarack, American Larch
Botanic Family	Pinaceae, Pine Family
Native Range	Eastern northern United States to Minnesota, all of Canada
Native Plant Community	Acidic, nutrient poor wetlands, such as sphagnum bogs, peaty lakeshore edges, and boggy stream margins; sometimes occurs in uplands.
Hardiness Zone	USDA zones 2b to 5b
Mature Size	40’-80’ tall, 30’-50’ wide
Leaf description	Deciduous needles in bundles of 10 to 20; soft to the touch
Shape/Form	Pyramidal
Summer Texture	Fine
Winter Texture	Coarse
Flower	Male and female flowers in separate structures on the same tree (monoecious), male flowers are small cone-like structures; female flowers are rosy pink cones that become woody when pollinated
Fruit	Small persistent (1/2 inch) woody cones, light brown, upright on stems.
Fall Color	Golden yellow
Soil Preferences	Prefers moist, acidic soil, tolerates alkaline soil, tolerates medium soil moisture, sand, loam, clay
Compaction Tolerance	Tolerant
Root Pattern	Shallow roots make this tree prone to wind throw
Light Preferences	Full sun
Tolerant of drought?	No
Tolerant of flooding?	Yes
Tolerant of soil salt?	No
Tolerant of salt spray?	Yes
Growth Rate	Fast
Life Expectancy	Long (up to 180 years)
Ease of Transplanting	Easy
Wildlife Value	Birds, Browsers, Small mammals
Landscape Use	Anywhere that has room for a large tree and moist acidic soils, parks, residential, raingardens
Diseases, Pests and Potential Problems	Generally low maintenance tree with few problems. Potential insect pests include larch case-bearer, larch sawfly, larch looper, tussock moth, Japanese beetle and woolly aphids. Potential disease problems include needle cast, needle rust and canker.
Other Unique Characteristics	Pink cones in spring, soft clusters of needles in summer, golden needles in fall, persistent brown cones in winter, loses needles in winter

Taxodium distichum, Bald-cypress

Native to the Southeastern U.S., Taxodium distichum, Bald-cypress, is another conifer that loses its needles in winter. Its fall color is a coppery red. Other unique features are its attractive, fibrous, reddish-brown bark, and the buttressing and “knees” it develops in flooded areas. It is a hardy, tough tree that adapts to a wide range of soil types.

Scientific Name	Taxodium distichum
Common Name	Bald-cypress
Botanic Family	Cupressaceae, Cypress Family
Native Range	Southeastern United States, south and east from a line from from Illinois to Texas
Native Plant Community	Swamps, bayous and rivers
Hardiness Zone	4 to 11
Mature Size	50-70’ tall, 20-30’ wide, can grow taller than 100’
Leaf description	Soft, feathery needles
Fall Color	Coppery red
Shape/Form	Columnar to pyramidal, occasionally broad spreading canopy
Summer Texture	Fine
Winter Texture	Medium
Flower	Male and female flowers in separate structures on the same tree (monoecious), inconspicuous
Fruit	Small round cones stay on branches into the winter
Soil Preferences	Prefers wet, acidic soil but tolerates drier soils and alkaline soils, sand to clay
Compaction Tolerance	Tolerant
Root Pattern	Taproot, develop “knees” (conical structures that grow from lateral roots), especially in flooded areas, buttressed base, especially in flooded areas
Light Preferences	Full sun
Tolerant of drought?	Moderately drought tolerant
Tolerant of flooding?	Tolerant
Tolerant of soil salt?	Intolerant
Tolerant of salt spray?	Tolerant
Growth Rate	Moderate
Life Expectancy	Long
Ease of Transplanting	Easy
Wildlife Value	Birds, Small mammals, Water birds
Landscape Use	Specimen, massing, anywhere large enough for such a large tree, parks, raingardens, street tree, lakeshores, parking lot islands
Diseases, Pests and Potential Problems	No serious insect or disease problems. Chlorosis often occurs in alkaline soils. Bagworms, gall mites, cypress moths, and spider mites are occasional insect pests and twig blight is an occasional disease pest.
Other Unique Characteristics	Loses needles in winter, attractive, fibrous, reddish-brown bark.

Metasequoia glyptostroboides, Dawn Redwood

A very large tree native to China, the Dawn Redwood was thought to be extinct until it was found in China in 1941. Similar to the Bald Cypress, it prefers wet, acidic soils. Its soft green needles turn a brilliant orange in the fall. Gilman and Watson (1994) consider to the “the most outstanding part of the tree” to be “its unique orange red to brown trunk base [that] tapers and thickens quickly with 8 to 12 large buttress-like root flares extending several feet up the tree in a manner unlike any other tree except some tropical trees.”

Scientific Name	Metasequoia glyptostroboides
Common Name	Dawn redwood
Botanic Family	Cupressaceae, Cypress Family
Native Range	Central and western China
Hardiness Zone	(4)5 to 8, damaged by early frost
Mature Size	70-100’ tall, 15 to 25’ wide
Leaf description	Linear, feathery, fern-like foliage that is soft to the touch, deciduous
Fall Color	Showy, bronze red/orange yellow
Shape/Form	Conical, pyramidal
Summer Texture	Fine
Winter Texture	Medium
Flower	Male and female flowers in separate structures on the same tree (monoecious), inconspicuous
Fruit	0.5 to 1” round brown cone, persistent
Soil Preferences	Acid, medium to wet, not tolerant of alkaline soils, sand to clay
Compaction Tolerance	Intolerant
Root Pattern	Trunk “tapers and thickens quickly with 8 to 12 large buttress-like root flares extending several feet up the tree in a manner unlike any other tree except some tropical trees” (Gilman and Watson 1994).
Light Preferences	Full sun
Tolerant of drought?	Tolerant
Tolerant of flooding?	Tolerant
Tolerant of soil salt?	Intolerant
Tolerant of salt spray?	Moderately tolerant
Growth Rate	Fast
Life Expectancy	Long
Ease of Transplanting	Easy
Wildlife Value	No
Landscape Use	Needs a large space, street tree, raingarden, parks, wide medians, specimen, screens, parking lot islands
Diseases, Pests and Potential Problems	Usually problem free, cankers can occur
Other Unique Characteristics	As the tree matures, the trunk broadens at the base and develops attractive and sometimes elaborate fluting; attractive bark; reddish-brown bark peels into long strips

While many arborists and designers know the deciduous conifers included in this blog, most people who are not in a tree related profession don’t know there are deciduous conifers. So, as you admire changing colors this fall, consider including deciduous conifers in your next urban designs/plantings to increase diversity and interest in the urban forest. All three of these are very low maintenance given the right growing conditions, and tolerant of quite a wide range of growing conditions (though none tolerate soil salt). With a preference for wet soils, but tolerant of drought, they are ideal for use in larger bioretention areas as long as they will not be exposed to heavy salt use.

We’ll be featuring three to four trees, grouped by different characteristics, in each of the articles in this series. Have a grouping or category of trees you’d like us to cover? Let us know in the comments.

Sources

Dirr, Michael. 1998. Manual of Woody Landscape Plants. Stipes Publishing: Champaign, IL.
Gilman, Edward, F. and Dennis G. Watson. 1994. Taxodium distichum, Baldcypress. USDA Forest Service Fact Sheet ST-620. Downloaded from the U.S. Forest Service.
Gilman, Edward, F. and Dennis G. Watson. 1994. Metasequoia glyptostroboides, Dawn Redwood. USDA Forest Service Fact Sheet ST-407. Downloaded from  here.
Holm, Heather. 2015. Great Design Plant: Larix Laricina Glows Gold in Late Autumn.
Minnesota Department of Transportation Plant Selector
Missouri Botanical Garden Bald Cypress website
Missouri Botanical Garden Dawn Redwood website
Missouri Botanical Garden Tamarack website
Morton Arboretum Bald Cypress website
Morton Arboretum Dawn Redwood website
Morton Arboretum Tamarack website
Smith, Welby. 2008. Trees and Shrubs of Minnesota. University of Minnesota Press: Minneapolis.

 

Nathalie Shanstrom is a sustainable landscape architect with The Kestrel Design Group. Top image is of Lincoln Road Mall (Miami, FL) courtesy of Raymond Jungles.