[1. Paulownia tomentosa (Thunb.) Steud. (royal paulownia, empress tree, princess
tree)
Pl. 480 a, b;
Map 2183
Plants trees to
15 m tall. Bark smooth when young, developing a network of irregular shallow
furrows with age, brownish gray. Twigs stout, with prominent white lenticels,
hairy and somewhat sticky when young, the leaf scars prominent. Leaves opposite
or less commonly whorled, lacking stipules, simple, long-petiolate. Leaf blades
8–70 cm long, ovate, sometimes very shallowly 3(5)-lobed or angled toward the
base, cordate at the base, tapered to the sharply pointed tip, the margins
otherwise entire, the upper surface sparsely pubescent with mostly fascicled
hairs, the undersurface densely pubescent with stellate and fascicled hairs.
Inflorescences large terminal panicles. Flowers perfect, hypogynous, without
subtending bracts. Calyces actinomorphic or very slightly zygomorphic, 5-lobed
to about the middle, densely pubescent with orangish brown stellate hairs, the
lobes broadly triangular-ovate, rounded to bluntly pointed at the tip. Corollas
5–7 cm long, zygomorphic, glandular on the outer surface, 5-lobed, the tube
bell-shaped, the lobes shorter than the tube, appearing obliquely 2-lipped,
light violet to blue with darker purple spots and longitudinal yellow stripes
in the throat. Stamens 4, the filaments fused to the corolla tube, the anther
sacs attached at the base, conspicuously spreading. Staminodes absent. Pistil 1
per flower, of 2 fused carpels. Ovary superior, with 2 locules, the
placentation axile. Style 1 per flower, the stigma 1, entire or shallowly
2-lobed. Ovules numerous. Fruits capsules, 3–4 cm long, 2-valved, ovoid,
tapered to a beak at the tip, longitudinally dehiscent, the valves glabrous,
with a woody texture. Seeds 2.5–4.0 mm long, oblong-elliptic in outline,
flattened, dark brown, with a thin irregular longitudinal wing around the
middle. 2n=40. April–May.
Introduced, uncommon
and widely scattered, mostly in the southern half of the state (native of
China, widely cultivated and escaped sporadically in the southern and eastern
U.S.). Mesic upland forests; also roadsides, railroads, fencerows, and open
disturbed areas.
Empress tree is
commonly cultivated as a shade tree and ornamental for its beautiful, sweetly
scented flowers. In the northern portion of its introduced range (including
Missouri), the pithy branch tips are sometimes damaged by cold temperatures
during harsh winters, especially on younger plants or stump sprouts. Flower
buds are formed in the autumn and overwinter, and the plants flower in the
spring before the leaves are fully expanded. After dehiscence, the large
displays of woody fruits also persist during the winter months. In some
southeastern states, Paulownia is also cultivated as an extremely
fast-growing timber tree. The soft lightweight whitish wood is mostly exported.
In some portions of southeastern Missouri, it is somewhat invasive in mesic
upland forests.