Tree of the Month – Black Gum (Nyssa sylvatica)
Posted: November 2, 2012
Also known as sour gum or black tupelo, Nyssa sylvatica has an attractive growth habit and dependably good fall color. While there have been issues with transplanting and establishment in the past, advances in growing trees in containers and in our knowledge of proper planting practices make this a species to consider adding to your plant palette.
Nyssa sylvatica is native to eastern North America, from Ontario and Maine, south to Florida, and west to Texas. In the wild, it is often found on dry upland sites, but is also at home on the edges of swamps and bogs. While Nyssa sylvatica is best in full to part sun and moist, well-drained, acidic soils, the variety of habitats it occupies in the wild is testament to its adaptability. It is even tolerant of deicing salts. The only limitation is its intolerance of high pH soils; a pH of 5.5 to 6.5 is a must.
There is tremendous variability in wild populations, but Nyssa sylvatica grows 30 to 50 feet tall with a spread of 20 to 30 feet. Young trees have a pyramidal growth habit similar to pin oak (Quercus palustris). They mature to an upright-oval to irregularly rounded habit. The foliage is glossy dark green in summer, with fall color ranging from brilliant yellow and orange to blazing scarlet and purple. While many trees looked scorched and shabby by August thanks to our hot, dry summer, a well-established black gum that I encounter frequently looked just as fresh as it did when it leafed out in spring – with no supplemental irrigation.
Nyssa sylvatica is polygamo-dioecious, which means that trees are primarily dioecious, but that some bisexual flowers appear, enough that fruit may be sparsely produced on primarily male trees. The flowers are interesting, but not showy. The small drupes ripen to blue-black and are eaten by a variety of birds and mammals.
One negative is that Nyssa sylvatica is susceptible to a leaf spot disease that spoils the beauty of the foliage. The cultivar Red Rage® (‘Hayman Red’) is reported to be resistant. Other cultivars include:
- ‘Autumn Cascades’: a weeping form with an irregular habit and outstanding fall color.
- ‘Wildfire’: new growth emerges with a reddish color that persists into summer.
- ‘Zydeco Twist’: slightly contorted, zigzag branches add winter interest to black gum’s ornamental attributes.