Once you understand how and where to look, distinguishing a black gum tree (Nyssa sylvatica) from a live oak (Quercus spp.) Becomes simple. Form, foliage, flowers and vegetables all highlight the gaps between these trees. Black gum simplifies the task once it drops its leaves for winter. A live oak — as its name implies — remains evergreen. Southern live oak (Quercus virginiana) illustrates that the qualities that separate various types of live oaks from a dark gum tree.
Silhouette and Size
Black gum’s characteristic pyramidal shape remains intact during its existence. Narrow but conical when young, the tree gradually widens as it ages. In Mediterranean-climate landscapes, black gum generally grows 30 to 50 feet tall and 20 to 30 feet broad. It grows much larger in its native eastern U.S. habitat however still includes a pyramidal type. Southern live oak grows 50 feet tall in Mediterranean climates and taller in its native southern U.S. kingdom; its rounded, umbrellalike canopy spreads twice as broad as the tree grows tall. A broad southern live oak on the horizon won’t be mistaken for a black gum tree.
Leaf Characteristics
Following a winter spent with bare branches, black gum creates shiny, green foliage in spring. Each widely oval leaf widens at the center prior to its smooth margins form a stage. Even in mild climates, black gum treats onlookers to a fiery show of orange, red, purple and gold foliage before fall takes its leaves. The southern live oak holds its leaves year-round in all but the coldest regions of its growing range, and also it falls only a portion of its leaves. The narrow, oval, smooth-edged leaves have softly rounded tips and are shiny and dark green on top and white beneath.
Preferred Conditions
Black gum and southern live oak develop best in full-sun and partially shady websites, and both bear highly acidic to highly alkaline soil pH. Hardy at U.S. Department of Agriculture plant hardiness zones 5 through 9, dark gum withstands wide-ranging dirt and soil conditions. Compacted, drought-stricken, urban plots and excessively moist, poorly drained sites evenly match the versatile black gum. The tree has moderate salinity tolerance at a coastal site. Hardy in USDA zones 7 through 10, southern live oak adapts to a range of conditions, but its optimal growth requires always moist to wet soil. Even so, southern live oak excels in warm, inland climates and low-desert gardens that provide sufficient moisture. Its salinity tolerance is great to medium on a shore and great at an inland site.
Flowers and Fruits
Some tree flowers have male and female parts within the exact same blossom, but dark gum flowers are either male or female. With occasional exceptions, the male and female flowers occur on separate trees. Following a male black gum tree flowers pollinate a feminine black gum tree inconspicuous spring blooms, the feminine tree bears fruits, that appear in clusters and are dark or blue-black, 1/2- to 1 1/2-inch, olivelike drupes in autumn and winter. Southern live oak also has separate male and female blooms, but they appear on the exact same tree. Those blooms are trivial and appear in spring; they give 1/2- to 1 1/2-inch vegetables — brown acorns with spiny tips.
Additional Live Oaks
While dark gum blazes with fall color and berrylike fruits, live oak species native to Mediterranean, coastal climates stick with acorns and spiny, evergreen leaves. The coast live oak (Quercus agrifolia) is among these species, and canyon live oak (Quercus chrysolepis) is just another one. Hardy in USDA zones 9 through 10, the coast live oak grows up to 70 feet tall, has a canopy spread wider and creates acorns quantifying 1 1/2 to 3 inches. Every spring, it deals leathery old leaves for shiny new ones — all with sharp, spiny borders. The canyon live oak is hardy in USDA zones 8 through 10, grows 65 feet tall and broad, and has sharp-tipped, 1/2- to 1 1/2-inch acorns. Its leaves may have sharp spines or be smooth; one tree may have both spiny leaves and smooth leaves. Each leaf is gray-green on the planet and pale-blue on its bottom.