Nyssa sylvatica, Black Gum – 4 (3)

By Tom Atkinson

Black gum, pepperidge, tupelo – these are a few of the vernacular names for that delight among Mother Nature’s panoply of large woody plants known as trees – Nyssa sylvatica. Not too long ago I knew nothing about this plant, but now that I have “seen the light” I wander about preaching its virtues with a missionary’s zeal.

The range of Nyssa sylvatica is extensive, from Ontario and New England, south through the eastern United States, veering west to Texas and even into upland areas of central Mexico. In the region that is familiar to me, extreme southern Ontario, black gum is found in areas that stay moist due to ephemeral spring flooding and a high water table. One of these is the NANPS’ nature reserve, known as Shining Tree Woods, on the northern shore of Lake Erie.

To see a black gum as stripling, perhaps three to five metres high (three to five yards), is to view an Adonis of woody plants: sheer beauty with a strong central leader, horizontal to slightly downward-sloping branches, an almost stripped-bare conifer in outline. The leaves are thick and shiny dark green. Bark on young trees is smooth, greyish-brown to grey. As expected of a member of the Cornaceae or Dogwood family, mature black gum specimens (up to 20 metres or 65 feet tall in Ontario, taller further south) have bark that has darkened and broken into plates. (I sometimes think of tectonic plates since these plates do move as the tree grows.)

The spectacular autumn colour convinced me that this was a must-have (it worked on my wife too and she is hardly a pushover for most of the plants that I consider to be little gems in our backyard). Black gum is similar to a young beech (Fagus grandifolia) in bark and outline. But while beech leaves are a glorious chocolate brown in fall, black gum leaves are scarlet or crimson. At “worst”, they are shiny yellow to burnt orange. (To be truly moved visit aggie-horticulture.tamu.edu/ornamentals/natives/trees/Nyssasylvs1704.jpg for a photo of its shiny red leaves.) .

Black gum has continental cousins that are at least as intriguing. Swamp tupelo, Nyssa sylvatica var biflora, normally develops a taproot and has a swollen base to the mean height of the growing season water level. Water roots, which develop under flooded conditions, help support the tree and capture nutrients. These specialized roots tolerate high carbon dioxide concentrations, oxidize the rhizosphere* and carry on anaerobic respiration. Ogeechee tupelo (Nyssa ogeechee) is a denizen of the deep south. It is used to make tupelo honey. The mature fruit, known as Ogeechee lime, has a subacid flavor. It is made into preserves and also used for a beverage.

If you wish to propagate your own black gum, rest assured that it is simple. To get fruit you need to have both a male and a female. The mature dark blue fruits are easy to spot among the delightful burnt orange-to-crimson leaves on the female tree. The fruit is just under one centimetre (about two-fifths of an inch) in length. Squeeze the fruit, which is oily, and a single seed is your reward. When you collect seed, limit your take to no more than 10% of what you find.

Take your seed home and either outplant it or pot it up as soon as you can. If you outplant it, do so in a row, with a marker at each end of the row. Growing in a row means that when the seeds germinate next year, seeing lookalike plants growing in that row means it’s a lead-pipe cinch that they represent what you planted. If you plan to use pots, get moist sterilized potting soil, fill the pot, cover the seeds with at least a centimetre of potting soil and get it very wet. (In fact, Mary Gartshore of Pterophylla, a native plant nursery, offers the best advice: “Overwinter them in muck.”). Seal the pot inside a freezer bag and tag it. The pot needs to be stored in a location where the temperature will be near freezing over winter. Germination will occur in spring. Make sure the pots and seedlings are put outside during the growing season. Growth is always stronger this way. (If the plants start to grow inside, the leaves may become UV-scorched when the plant is finally taken outdoors. This is unsightly, but that is all.) I keep pot-started seedlings in pots over the first winter after germination. This is where the muck comes in. Keep the soil wet. Outplant the seedlings the second spring.

Black gum needs an “acid foot”, soil high in organic matter with a pH of 6.5 or less. Although this can be achieved without artificial additives I find it is still necessary to use peat, a practice not recommended by naturalists since the mining of this resource is unsustainable and damages valuable ecosystems. Still, in this instance I see no recourse. Peat is needed to get a black gum going. However, once the plant is established, it can often take care of itself. Growth may be slower or the foliage chlorotic (yellowed) if conditions are not ideal, but the tree will survive. The young black gums in our garden are faring nicely now.

If you do not wish to start a Nyssa sylvatica yourself, purchase one from a local nursery (vs. far-away or churn-‘em-out-to-make-money nurseries). The small grower cares, often collecting seed from nearby locations and propagating the plants. Buying from a local ethically run nursery means that your black gum will do better for you than one trucked in from a great distance – and a warmer (or colder) hardiness zone. Mind you, Nyssa sylvatica is rated USDA zones 4 to 9.

Even if you do not plan to plant a black gum, do yourself a favour and go out in search of one. If they do not grow naturally in your region, check out a local arboretum or cemetery. You will be delighted with your find.

* The rhizosphere is the zone surrounding the roots of plants in which complex relations exist among the plant, the soil microorganisms and the soil itself. The plant roots and the biofilm associated with them can profoundly influence the chemistry of the soil including pH and nitrogen transformations.

Tom Atkinson is a native woody plant propagator as one of his avocations. A semi-retired software developer with IBM, Tom numbers among his interests field botany and gardening featuring native plants. He welcomes your inquiries or correspondence at asimina@sympatico.ca. The id (Asimina) refers to another of Tom’s favourite trees.