Stewartia malacodendron (Silky Stewartia)

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IN YOUR GARDENStmalacodendron'Delmarva'

Type: Deciduous tree
Hardiness Zone: 6(7)-9
Sunlight: Shade
Soil Moisture: Well drained
Soil pH: Acid (4.5-6.5)
Flowering: Late April – June
Flowers: White with purple stamen filaments and bluish anthers
Leaves: Green to yellow fall color
Height: to 10 feet



Shrubs or small trees to 7 m.; young branches pubescent, the periderm reddish brown, flaking in irregular longitudinal strips; bark tight, close, silvery gray, non-exfoliating; winter buds compressed, 5-9 mm. long, with 2 densely silvery-pubescent imbricate scales. Leaf petioles 2-4 mm. long, shallowly grooved on the adaxial surface; leaf blades (2.5-) 5.5-11 cm. long, (1.1-) 2.5-5 cm. wide, ovate to elliptical with acute or acuminate apices, cuneate to attenuate bases, and finely serrulate, obscurely ciliate margins; upper surfaces of the blades glabrous, the lower surfaces finely appressed-pubescent, particularly along the midveins. Flowers axillary, the pedicels short, up to 5 mm. long; bracts subtending the calyx 2, ovate to suborbicular, 2-4 mm. long, 2-4 mm. wide, with short apiculate apices, persistent. Sepals 5, connate at base, 8-11 mm. long, 5-9 mm. wide, the free lobes suborbicular to obovate with ciliate margins and apiculate apices, persistent and reflexed in fruit. Petals 5, connate at base, (3-) 4-5 cm. long, 3-4(-4.9) cm. wide, obovate to suborbicular in outline with entire or erose, wavy margins, the abaxial surfaces sericeous toward the base. Stamens numerous, the filaments purple, connate at base, forming an ill-defined tube ca. 1 mm long, the tube entirely adnate to the base of the corolla; free portions of the filaments up to 10 mm. long, pubescent at base; anthers bluish. Ovary ca. 5 mm. long at anthesis, subglobose, 4- or 5-angled, densely sericeous, the style glabrous, 3-5 mm. long, terminated by 4 or 5 stigmatic crests. Capsules woody, reddish brown, finely appressed pubescent, subglobose, 4- or 5-angled, often broader than long, 12-16 mm. long, 12-18 mm. broad, with apiculate apices, the base of the deciduous style projecting 1-1.5 mm. from the apex of the capsule; capsule dehiscing into 4 or 5  locules, by the outward and backward folding of the lateral margins of the valve walks, the apices of the valves remaining coherent or only slightly separated, one or two of the valves rarely deciduous. Seeds 2 or 4 per locule (or fewer through abortion), 5-7 mm. long, 4-6 mm. wide, angular, ovate to subovoid in outline, wingless, lustrous purplish or reddish brown. 2n=30.




GLOBAL DISTRIBUTIONMalacodendron GlobalDistribution

Occurring in scattering localities on the Coastal Plain and Piedmont in the southeastern United States from Virginia to Florida and west to Mississippi, Louisiana, and Arkansas; known from two localities in the mountains of North Carolina and recently discovered in Newton County in eastern Texas. It is considered rare in Georgia and endangered in both Arkansas and Florida.





    • PHA Stewartia malacodendron ‘Delmarva’ – “In 1961 William Frederick, guided by Jacques Legendre, walked through the woodland in the Virginia tip of the Delmarva Peninsula. Their goal was to find Stewartia malacodendron, the “silky stewartia.” Bill gave me eight seeds of this native southern species, which I stratified, then planted in 1962; two plants resulted. In 1963 one was planted in the Arboretum Field South, on the wall, but it was girdled by mice in 1971. It grew briefly from the base but died. The other seedling was planted in the Arboretum Field at the far west end where there is an opening in the wall to the West Filed. In 1989, 27 years from seed, the first flowers opened on an 8-foot tree. The 2-inch flowers with purple stamens, blue anthers, and a splash of crimson on one of its five petals, ornament this attractive small tree. In a storm, a large locust tree fell across the area, badly damaging ‘Delmarva’, as I had named it. But staking and pruning revived the tree for another time. The great snowstorm of 1999 once again decimated ‘Delmarva’. This greatly admired tree is delicate, graceful, and vulnerable. ‘Delmarva’ is hard to propagate from cuttings. Over the years I have never succeeded in germinating the seeds it has produced. If I only had another tree of the species: perhaps the seeds need cross pollinating to be viable.” From the notes of Polly Hill.


Tree logo indicates introduction by Polly Hill

Descriptions from Stephen A. Spongberg, 1974, A Review of Deciduous-Leaved Species of Stewartia (Theaceae), Journal of the Arnold Arboretum 55: 182-214.