Underutilized Trees for Urban Use: Korean Mountainash

Fruit and sporadic fall leaf color of Korean mountainash. Photo by Michelle Sutton

Underutilized Trees for Urban Use: Korean mountainash (Sorbus alnifolia)

By Michelle Sutton, Council Editor

I can think of few trees with the year-round beauty of Korean mountainash (Sorbus alnifolia). It is notable for its delicate and showy white spring flowers, handsome deeply veined summer foliage, yellow to orange fall color, reddish-pink berries in fall and early winter, and elephantine bark in winter (beech-like, but with distinct white markings). Its potential height is 20 to 40 feet and potential width 15 to 25 feet. The cultivar ‘Redbird’ has rosy-red fruits and a more upright form.

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Underutilized Trees for Urban Use: ‘Harvest Gold’ Linden

Glossy summer foliage of ‘Harvest Gold’ linden. Photo by James Kaechele

This post comes to us from NYSUFC Board Member and New York Tree Trust Development Director James Kaechele. 

Harvest Gold Linden (Tilia cordata x mongolica ‘Harvest Gold’)

As an open-pollinated hybrid of T. cordata and T. mongolica, ‘Harvest Gold’ linden steals the best from each parent. Searching through rows of lindens at Moon Nursery in Chesapeake City, Maryland in early 2009, I noticed this tree was different. ‘Harvest Gold’ does not share the liability of ‘Greenspire’ linden’s wide and twiggy form. Nor does it suffer from the often sparse crown of a young ‘Redmond’ or the frequently crowded branching of silver linden. Time may still reveal a fatal flaw for ‘Harvest Gold’, but after planting and observing it for the last ten years across diverse New York City landscapes, I am prepared to say this is an excellent linden.

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Underutilized Trees for Urban Use: Japanese Snowbell

Drupes of Japanese snowbell (Styrax japonica) Photo by Michelle Sutton

Japanese snowbell (Styrax japonica) is often confused with its Styracaceae family cousin, Carolina silverbell (Halesia carolina). While their flowers are similarly white, pendulous, and bearing yellow stamens, their foliage and fruit are very different. Japanese snowbell foliage is glossy and elliptic-obvate, with leaf tips curving upwards, and its fruits (drupes) look like little green (and eventually brown) olives; you’ll recall Carolina silverbell has longer, matte/dull leaves, with fruits that are football-shaped.

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Underutilized Trees for Urban Use: Carolina Silverbell

Carolina silverbell (Halesia carolina) flowers. Photo from MOBOT Plant Finder (missouribotanicalgarden.org/PlantFinder)

Carolina silverbell (Halesia carolina) produces fruits that look more like winged footballs than bells. Thus, one taxonomic synonym for this tree is Halesia tetraptera, where tetraptera means “four wings.” Carolina silverbell falls in that category of urban trees that are best used in parks, campuses, generously wide tree lawns, and other places where the influence of the built environment (asphalt, concrete) on the soil pH is not too profound. This is because it can’t tolerate highly alkaline soil and indeed prefers acidic soil where possible. In high pH-soils, its leaves can appear chlorotic (yellowed).

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Underutilized Trees for Urban Use: Chinese Fringe Tree

Chinese fringe tree (Chionanthus retusus) foliage is darker, glossier, rounder, and more leathery than native fringe tree (C. virginicus) foliage, and its flower petals have rounded ends and appear less feathery than those of the native tree. Photo by Bill Haws

There’s some disagreement about the true native (vs. naturalized) range of white fringe tree, Chionanthus virginicus. Although it appears to be indigenous to the Southeast U.S. at least, the potential planting range of this small tree, hardy to USDA Zone 3, is the entire continental U.S. Unfortunately, white fringe tree has been found to be quite vulnerable to Emerald Ash Borer (EAB) like its Oleaceae family cousins, ash trees.

Young Chinese fringe tree habit and showy bloom. Chinese fringe tree can be grown as a standard in tree form, with a mature height and width range of 15 to 25 feet. Photo by Bill Haws

Interestingly, Chinese fringe tree (Chionanthus retusus) has not been found to be vulnerable to EAB. It’s thought that since C. retusus co-evolved with EAB, this Asian iteration of fringe tree built up defenses to the beetle over millennia in its native eastern Russia, northern China, Japan, and Korea.

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SMA Announces 2019 Urban Tree of the Year

American hophornbeam (Ostrya virginiana) coping admirably well with the heat on the student union patio at Virginia Tech. Photo by Eric Wiseman

Each year, members of the Society of Municipal Arborists (SMA) vote for the SMA Urban Tree of the Year. Praise for this year’s winner, American hophornbeam (Ostrya virginiana), came from fans in states as far-flung as Wisconsin, New York, Virginia, and Texas.

Here, we hear from the Council’s Dr. Nina Bassuk at Cornell and from her colleague, Dr. Eric Wiseman at Virginia Tech. You can see the full list of SMA Urban Trees of the Year going back to the program’s inception in 1996 here.  

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Trees for Parks: Fall Fiesta Sugar Maple

Fall Fiesta sugar maple at Bold Spring Nursery in Georgia. Fall Fiesta is available in New York nurseries as well. Photo Courtesy Bold Spring Nursery

The Fall Fiesta sugar maple (Acer saccharum ‘Bailsta’) is a patented cultivar selected in 1987 from a group of seedlings at Bailey Nurseries in Yamhill, Oregon. It was chosen because of its vigorous growth rate; upright, symmetrical form; and leathery leaves that are resistant to scorch and tatter caused by droughty or windy conditions, respectively.

Fall Fiesta is an excellent shade tree with a dense, rounded crown; it maintains its shape and requires little pruning. Its fall color may consist of more oranges and reds than other sugar maple varieties, and it exhibits excellent winter hardiness, from USDA Zones 3 to 8. Healthy trees don’t have significant pest or disease problems. 

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