Seeds and cuttings I collect around North Carolina, what they turned out to be, and how to grow them for a NC Piedmont native-plant nursery.
Oxydendrum arboreum · Ericaceae
Sour-leaved heath tree. Drooping white sprays in July, crimson early in fall, dust-fine seed shed from silver-gray capsules through winter.
Community photos of Oxydendrum arboreum to study before I head out: leaf, flower or bract, ripe fruit, bark, whole plant.
Common throughout the NC Piedmont uplands and lower mountains, present in Person County; its eastern limit reaches the edge of the Coastal Plain, so it thins out only in the low alluvial east
Best bet: Air-dry whole capsules in a paper bag until they split, then shake out the powder-fine seed. Surface-sow on a moist acidic peat and pine-bark mix and do not bury it; the seed is light-requiring, so press it in only. Cold-moist stratification is optional rather than required, but 30–60 d at about 40°F hastens germination and cuts the light requirement. Hold under mist or a humidity dome at a 25/15 to 30/20°C day/night and never let the surface dry out. Cuttings are unreliable, with only summer softwood heel cuttings under mist rooting in trials, so seed is the dependable route.
A Piedmont native understory tree, perfectly at home in Roxboro and Person County. Wants acidic well-drained soil, and tolerates the region's clay uplands as long as drainage is good and pH stays acidic. Avoid lime, since like most Ericaceae it shuns limestone soils. Fully cold-hardy for the Piedmont (zone 7b/8a). Cautions: it is slow-growing and resents root disturbance, so grow from seed rather than moving wild plants; the dust-fine seed makes germination finicky and moisture-sensitive; young trees want protection from drought. No invasiveness and few serious pests.
Each look-alike with the one character that settles it. Tap a photo to zoom.
Leaf margins entire and fruit a fleshy blue-black drupe, where sourwood has finely serrate leaves and dry woody capsules. Both flare crimson early, so check margin and fruit rather than color
Rusty-orange hairs along the midrib beneath and a bitter-almond smell in scraped twig or bark. Sourwood's midrib is hairless and the leaf tastes sour, not almond
Leaves entire and oval, fruit an orange fleshy berry. The blocky bark looks much alike, so go by the toothless leaf and pulpy fruit against sourwood's serrate leaves and dry capsules
Sourwood is a small, often crooked-leaning understory tree of the Piedmont's dry upland woods: oak-hickory and oak-pine slopes, ridgelines, and forest edges on acidic well-drained soil. Two windows make it easy. In July I look up into the mid-story for drooping one-sided sprays of tiny waxy-white urn-shaped flowers, the lily-of-the-valley firework. Honeybees swarm it, so a humming tree is worth walking toward. In late September and October it is one of the first understory trees to blaze crimson-scarlet, often while everything around it is still green. What I'm scanning for is a slender tree with a lopsided arching crown, glossy peach-like leaves, and blocky ridged bark.
September through November. Gather the erect dry capsules off the drooping panicles as they turn green to silver-gray, before they split and shed. The seed matures late and disperses gradually through winter, so summer-green capsules are immature; wait for graying. Cleaning is easy: air-dry the capsules in a paper bag until they split, then shake out the dust-fine seed. That fineness is the nursery headache here, since one skipped watering kills a whole flat of seedlings.
Sowing hinges on two things. The seed is light-requiring, so surface-sow on a moist acidic peat and pine-bark mix and press it in, never bury it, then keep it under mist or a humidity dome. Best germination runs at a 25/15 to 30/20°C day/night. Cold-moist stratification is optional, though 30–60 days near 40°F hastens germination and reduces the light needed. Cuttings are unreliable, with only summer softwood heel cuttings under mist rooting in trials, so I plan on seed.
Around Roxboro, work the acidic wooded slopes and shorelines at Mayo Lake Park and Hyco Lake, and the uplands of Person County Game Land. Farther out, reliable Piedmont stands sit in Duke Forest, Eno River State Park, Occoneechee Mountain, and the drier edges of Uwharrie National Forest. Scout in October when the crimson gives them away, then return for capsules.