Rafinesque's Arrow-wood
Viburnum rafinesquianum
Honeysuckle family (Caprifoliaceae)
Description:
This small deciduous shrub is 3-6' tall at maturity. The short trunk or
lower branches are gray and somewhat wrinkled, while upper branches are
gray and more smooth. Young shoots are light green to reddish green,
terete (round in circumference), and slightly pubescent (for the
typical variety) to glabrous (for variety affine). Widely scattered
white lenticels (air pores) occur on the upper branches and shoots.
Pairs of opposite leaves occur along the young shoots and branches.
These leaves are 1½–2½" long and 1-2" across; they are lanceolate-ovate
to orbicular-ovate in shape, while their slightly ciliate margins have
5-10 low dentate teeth on each side. The upper leaf surface is medium
green to reddish green and either glabrous or sparsely covered with
appressed hairs. The lower leaf surface is light to medium green and
either pubescent throughout (for the typical variety) or slightly hairy
along the veins and glabrous between the veins (for var. affine). The
petioles of the leaves are light green to red, convex below and grooved
above, very short (up to ¼" in length), and pubescent (for the typical
variety) to nearly glabrous (for var. affine).
At the base of each
petiole, there is a pair of persistent stipules; these stipules are
light green to reddish green, linear in shape, and about ¼" long. Many
upper shoots terminate in dome-shaped panicles of flowers that are
1½–3" across. Each flower is about ¼" across, consisting of a white
corolla with 5 spreading rounded lobes, a shallow light green calyx
with 5 short broad teeth, 5 exserted stamens with white filaments and
tan anthers, and a white pistil. The stiff branches of the
inflorescence are light green and usually slightly pubescent. The
blooming period occurs from late spring to early summer, lasting about
2-3 weeks. The flowers have an unpleasant fragrance. Afterwards, the
flowers are replaced by single-seeded drupes. At maturity, these drupes
are dark blue-violet to black, globoid to ovoid in shape, about 1/3" (8
mm.) long, and glabrous; they are fleshy and juicy inside. Each drupe
has a single stone (hardened seed) at its center. The stones are about
¼" (6 mm.) long, broadly ellipsoid in shape, and somewhat flattened.
The root system is woody and spreading. This shrub spreads by reseeding
itself. During the autumn, the leaves of this shrub become various
shades of
reddish-purple.
Cultivation:
The preference is full or partial sun, mesic to dry conditions, and
well-drained soil containing loam, clay loam, or some rocky material.
This shrub is very adaptable to cultivation in gardens and various
landscape settings. It tends to be more productive of flowers and fruit
in sunnier situations. This is one of the smallest viburnum shrubs.
Winter-hardiness is very good, especially if the stock has a northern
provenance.
Range
& Habitat:
Rafinesque's Arrow-wood is native to the upper half of Illinois, where
it is uncommon to occasional (see Distribution
Map).
This shrub is
found in the eastern-half of the United States and its range extends
into Canada. In mountainous and boreal areas, it can be common.
Habitats include bluffs, upland woodlands, wooded slopes, woodland
openings, woodland borders, and upland savannas. The dominant canopy
trees in these habitats are often oaks. In Illinois, this shrub is
typically found in higher quality natural areas.
Faunal
Associations: Most of the following information
applies to Viburnum spp.
(Viburnums, Arrow-woods) in general. The unpleasantly scented flowers
of Arrow-woods attract a variety of insects, especially short-tongued
bees, flies, and beetles. These insects feed on the nectar or pollen of
the flowers; some bees also collect pollen as food for their
larvae (Robertson, 1929). A variety of insects also feed on these
shrubs destructively. These species include Pyrrhalta viburni
(Viburnum Leaf Beetle), larvae of Oberea tripunctata
(Dogwood Twig Borer), the larvae of Sackenomyia commota
(Arrow-wood Blister Midge) and other gall flies (Cecidomyiidae), Lygidea
viburni and other plant bugs (Miridae), Aphis
viburniphila (Viburnum Aphid) and other aphids, the larvae of
Macrophya mixta and other saw flies, larvae of
the butterfly Celastrina
argiolus
(Spring/Summer Azure), the larvae of Agriopodes
fallax (The
Green
Marvel) and many other moths. See the Insect Table for a
more complete
list of these insect feeders.
Many songbirds and upland game birds feed
on the fruits of Viburnum spp., including
Rafinesque's
Arrow-wood. These species include the Ruffed Grouse, Wild Turkey,
Northern Flicker, Brown Thrasher, Hermit Thrush, Eastern Bluebird,
Cedar Waxwing, White-throated Sparrow, and others (see the Bird
Table
for a more complete list of these species). Some songbirds, including
the Hooded Warbler (Wilsonia citrina), also use these shrubs for cover
and nesting habitat
(DeGraaf, 2002; Bielefeldt & Rosenfeld, 2001). Mammals that
feed on
the fruits (and/or their hardened seeds) include the Black Bear, Red
Fox, Striped Skunk, Opossum, Fox Squirrel, Gray Squirrel, Striped
Chipmunk, and White-footed Mouse. Both the fruit-eating birds
and mammals that eat the fruit, but not the seeds, help to spread
the seeds of Rafinesque's Arrow-wood and other Viburnum spp.
to
new locations. The Cottontail Rabbit and White-tailed Deer occasionally
browse on the foliage and twigs (Martin et al., 1951/1961; Noyce
&
Coy, 1990; Rogers, 1987).
Photographic
Location: A shrubby garden along a sidewalk in
Urbana, Illinois. The less hairy variety of this shrub has been
photographed, Viburnum rafinesquianum affine.
Comments:
This is a small attractive shrub. Rafinesque's Arrow-wood can be
distinguished from other Viburnum spp.
by its small size (3-6' tall), the relatively few teeth along the
margins of its leaves (about 5-10 on each side), the short petioles of
its leaves (up to ¼" in length), the small linear stipules at the base
of its petioles, and its malodorous flowers (typical of Arrow-woods,
but not Viburnums). Depending on the variety, this shrub is variably
hairy. While the typical variety of this shrub (Viburnum
rafinesquianum rafinesquianum) has leaf undersides that are
hairy both on the veins and between the veins, the less hairy variety
of this shrub (Viburnum rafinesquianum affine)
has leaf undersides that are sparingly hairy along the veins only. Both
of these varieties can be found in Illinois and neighboring states.
Another common name, Downy Arrow-wood, is more suitable for the typical
variety of this shrub.