Korean Stewartia

(Theaceae - Tea Family)

Form

• medium-sized ornamental tree
• maturing to about 25' tall by 12' wide
• pyramidal growth habit in youth, becoming upright oval with age
• slow growth rate

Culture

• partial sun to full shade
• best performance occurs in partial shade in moist, well-drained, deep, acidic soils enriched with organic matter in a cool root zone location; not at all urban tolerant, including intolerance of alkaline pH soils, poor soils, poorly drained soils, heat, drought, pollution, and full sun
• propagated with difficulty, either by seeds, or by rooted stem cuttings that are overwintered before root disturbance
• Tea Family, with virtually no disease or pest problems, although severe stunting and chlorosis will occur in soils of alkaline pH
• rarely available, primarily in ball and burlap form (although Stewartia pseudocamellia is moderately available)

Foliage

• dark green, alternate, broad-elliptical, short-petioled, sparsely serrate, having an abruptly acute to acuminate apex, with the veins developing a very reticulate (net-like) pattern near the leaf margin
• Spring and Summer foliage is very clean, while fall color is a mixture of scarlet, pink, purple, orange, yellow, and green, being very effective and attractive in shady locations
• if the tree is placed in full sun, severe leaf scorch will often occur during the hot, dry periods of Summer

Flowers

• white and Camellia-like, in June and July, about 3" wide, with five or six wide-spreading petals that are obovate and wavy to crinkled at the margins, with orange-yellow stamens and filaments in the center of the very showy flowers, borne above the fully-expanded foliage on the current season's growth
• sparsely flowering throughout the canopy but, like Sweetbay Magnolia or Southern Magnolia, it has an extended bloom period of about four to six weeks

Fruits

• noticeable (but ornamentally insignificant) capsules are oval and woody

Twigs

• reddish-tan and distinctly zig-zag, with silvery-tomentose, prominent, conical, and pointed Winter buds, and with the lateral buds almost as large as the terminal buds
• stems of a given branch lie within the same plane, and overall the branches form a very symmetrical, low-branching, pyramidal growth habit

Trunk

• very ornamental (especially in Winter), a mottled combination of brown, gray, creamy-yellow, and orange, becoming very flaky (or exfoliating in short strips) with maturity
• bark is even more attractive when the tree is limbed up somewhat with maturity, allowing for more light to induce heavier exfoliation

ID Summary

• reddish-tan zig-zag twigs with silvery Winter buds, exfoliating mature bark of orange and cream hues, pyramidal to upright oval growth habit, and very showy white-yellow Summer flowers on the current season's growth, along with an excellent display of mixed fall color, contribute to the four-season appeal of this ornamental tree

USAGE

Function

• specimen or focal point tree, found at spacious shady foundations, as an understory tree surrounded by very tall and limbed-up shade trees, at shady borders or forest edges, or in open woodlands

Texture

• medium texture in foliage and when bare
• average density in foliage and when bare

Assets

• good four-season ornamental tree (Winter bark, branching, stems, and buds, Spring and Summer dark green foliage, very showy white Summer flowers, and outstanding Autumn foliage)

Liabilities

• intolerance of both alkaline pH soils (requiring acidic soils of pH 4.5 to 6.5) and full sun conditions (resulting in severe leaf scorch, stunting, and dieback)
• slow growth rate

Habitat

• zones 5 to 7
• native to Korea

SELECTIONS

Alternates

• specimen ornamental trees with multiseason appeal (Amelanchier x grandiflora, Cercis canadensis, Cornus florida, Cornus kousa, Crataegus viridis 'Winter King', Halesia carolina, Malus, Oxydendrum arboreum, Parrotia persica, etc.)
• trees with showy Summer flowers (Franklinia alatamaha, Koelreuteria paniculata, Magnolia grandiflora, Magnolia virginiana, Sophora japonica, Stewartia species, etc.)

Variants

• other species of Stewartia exist that differ in mature height and width, growth habit, flowers with purple (rather than yellow or orange) filaments, more highly ornamental bark, more solid fall color (typically orange, red, or scarlet), and better heat tolerance

NOTES

Translation

• Stewartia is named after John Stuart, an 18th century gentleman from Scotland (this genus was formerly known as Stuartia).
• koreana translates as "from Korea".

Purpose

• Korean Stewartia is a Summer-blooming ornamental tree that has four-season appeal, but is fastidious in its requirement for acidic soils.

Summary

• Stewartia koreana is known as a good four-season tree that is ideal for specimen usage, noted for its flowers, fall color, clean green foliage, and vibrant fall color.