4. Lonicera japonica Thunb. ex Murray (Japanese honeysuckle)
Map 1424, Pl.
334 c
Plants lianas to
5 m or more long, the main stems loosely twining, climbing on adjacent
vegetation or more or less trailing on the ground. Twigs sparsely to moderately
pubescent with spreading hairs, sometimes some of these with minutely glandular
tips, the pith hollow, the bark of older branches becoming shredded. Winter
buds conical, densely hairy. Leaf blades mostly 3–9 cm long, 1.5–4.5 cm wide,
ovate to oblong-elliptic, rounded or angled to short-tapered at the base,
angled or tapered to a sharply pointed tip, none perfoliate, the upper surface
glabrous or more commonly short-hairy along the midvein, bright green to olive
green, the undersurface sparsely to moderately pubescent with short, soft hairs
mostly along the main veins, occasionally also with scattered stiffer hairs,
not glaucous (pale green). Flowers in pairs in the axils of the leaves on
current years growth (first-year wood), each pair at the tip of a
stalk 1–25 mm long, the 2 bracts each 3–15 mm long, free, ovate to
oblong-elliptic (leaflike), hairy, the pair of bractlets on opposite sides of
each flower minute (0.7–1.2 mm long), free, oblong-ovate to nearly circular,
hairy along the margins. Calyces hairy along the margins, the lobes 0.7–1.5 mm
long, triangular to narrowly triangular, green, sometimes purplish-tinged.
Corollas 30–47 mm long, strongly zygomorphic, divided about 1/2 of the way to
the base into 2 recurved-curled lips of about equal length, the upper lip
shallowly 3-lobed, the lower lip with 2 deeper lobes, the tube slender and not
swollen or pouched near the base, white, turning cream-colored or pale yellow
after pollination, usually hairy and stalked-glandular on the outer surface.
Stamens and style exserted from the corolla, slightly longer than the corolla
lobes, the style glabrous. Ovaries free. Fruits 5–8 mm in diameter, black. 2n=18.
April–June.
Scattered nearly
throughout the state (native of Asia, introduced widely in the U.S., Canada). Bottomland forests, mesic
to dry upland forests, banks of streams, rivers, and spring branches, and
margins of ponds, lakes, and sinkhole ponds; also fencerows, old fields, old
homesites, railroads, roadsides, and mostly shaded disturbed areas.
Lonicera
japonica was once common
in horticulture because of its easy culture, rapid growth, numerous fragrant
flowers, and attractive twining habit. It has proven to be aggressively
invasive in a number of native plant communities in the state. In addition to
the fruits, which are dispersed by birds, the species can spread by woody
underground stems, and the aerial stems can root where they touch the ground.
Japanese honeysuckle forms dense mounds and smothers other plants, and it
sometimes girdles shrubs and small trees by twisting around their trunks. It
may be semievergreen in mild winters.