Description:
This is a low prostrate shrub about 2-8" tall that branches
occasionally, often forming a mat of trailing branches and leafy
shoots. The older branches are woody with thin bark; young shoots are
whitish green to red, more or less pubescent, and terete (circular in
circumference). Alternate evergreen leaves occur along the young
shoots; these leaves are ascending to widely spreading, and they
overlap more toward the tips of shoots than toward their bases.
Individual leaves are ½–1" long and ¼–½" across; they are oblanceolate
or oblanceolate-elliptic in shape, while their margins are entire
(toothless) and slightly ciliate. The upper leaf surface is dark green,
hairless, and shiny, while the lower leaf surface is medium green and
hairless. Leaf texture is leathery and leaf venation is pinnate. The
leaves taper gradually into short petioles about 1/8" (3 mm.) long.
Short clusters of 2-15 drooping flowers are produced from the tips of
last year's
twigs. Each flower is about ½" long and ½" across, consisting of a
white to pink urn-shaped corolla, a very short calyx with 5
half-orbicular lobes, 10 inserted stamens, and a glabrous ovary with an
inserted style.
The corolla is constricted around its neck, above which
there are 5 tiny lobes that are recurved and half-orbicular in shape.
The interior of the corolla is hairy. The lobed calyx is predominately
light green to red; its lobes have white- membranous margins. Both the
peduncle and pedicels of the inflorescence are light green to red,
glabrous to
short-pubescent, and terete. The blooming period occurs from late
spring to early summer, lasting about 2-3 weeks. Afterwards, fertile
flowers are replaced by drupes that develop during the summer. Mature
drupes are ¼–½" across, globoid to subgloboid in shape, smooth, and
bright red. The fleshy interior of each mature drupe is dry, mealy, and
tasteless, containing 4-5 hard seeds that are irregularly shaped. The
woody root system can extend 3-6' into the ground. This shrub
reproduces primarily by layering; when its branches and shoots become
submerged in sand or soil, they can develop new roots. By this means,
clonal colonies are produced. To a lesser extent, this shrub also
reproduces by reseeding itself. The evergreen leaves become red to dark
red during the winter.
Cultivation: The preference is full or
partial sun, dry conditions, and sterile soil containing acidic rocky
material or sand. Growth and development is slow. This winter-hardy
evergreen shrub can be started from rooted cuttings. It can be used as
a low ground cover in sunny rock gardens. The long-lasting drupes
can persist into autumn, winter, and early spring.
Range &
Habitat: The native Bearberry occurs primarily
in northern
Illinois, where it is rare and state-listed as 'endangered' (see
Distribution
Map).
However, some large healthy populations of this low
shrub can be found along the sand dunes of Lake Michigan. Illinois lies
along the southern range-limit of this species. Bearberry has a wide
distribution in boreal areas of North America; it also occurs in boreal
areas of Eurasia. Habitats include dry sandy woodlands, dry sandy
prairies, sandstone glades, exposed sandstone cliffs, and sand dunes
along Lake Michigan. In the latter habitat, Bearberry is often
codominant with Trailing Juniper (
Juniperus horizontalis).
This
conservative shrub is found in high quality natural areas. It is also
cultivated occasionally in gardens. Wildfire resistant is relatively
poor, although some crowns and submerged rooted branches can survive
light fires (Crane, 1991).
Faunal Associations: The urn-shaped
flowers are probably cross-pollinated by long-tongued bees, where both
nectar and pollen are available as floral rewards. A relatively small
number of insects feed on the leaves and other parts of Bearberry.
These species include two aphids,
Tamalia coweni
and
Wahlgreniella
nervata;
Clastoptera saintcyri (Heath
Spittlebug); two leafhoppers,
Limotettix arctostaphyli and
Texananus
cumulatus; the larvae of two
butterflies, C
allophrys augustinus (Brown Elfin) and
Callophrys polios
(Hoary Elfin); and the larvae of a Pyralid moth,
Pyla
arenaeola (see
Hottes & Frison, 1931; Hamilton, 1982; DeLong, 1948; Opler
&
Krizek, 1984; and Panzer et al., 2006). Two polyphagous insects,
Lepidosaphes ulmi (Oystershell Scale) and
Pseudococcus
sorghiellus
(Trochanter Mealybug), also reportedly feed on Bearberry. Foliage of
Bearberry is browsed sparingly by White-tailed Deer and Elk. However,
it is consider unpalatable and slightly toxic to horses, cattle, and
other livestock. The fruits of this shrub are eaten by various upland
gamebirds, songbirds, black bears, and small mammals, especially during
the winter and early spring, as a source of emergency food (see Crane,
1991; Martin et al., 1951/1961; Rumble &
Anderson,
1996). Most of these observations for vertebrate animals have occurred
in the western United States and Canada.
Photographic Location:
Sand dunes along Lake Michigan at Illinois
Beach State Park in NE Illinois.
Comments: Along with Trailing Juniper (
Juniperus
horizontalis),
Bearberry (
Arctostaphylos uva-ursi) plays an
important role in
stabilizing the sand dunes along Lake Michigan in NE Illinois. It is
typically found along the slopes or the tops of such dunes. Taller
shrubs that colonize this area include Low Common Juniper (
Juniperus
communis depressa), Sand Cherry (
Prunus pumila),
and Chokecherry
(
Prunus virginiana).
Bearberry has attractive flowers, fruits, and
foliage throughout the year. Because of its wide distribution, there is
some variability across different populations, and different
varieties/subspecies have been described. Bearberry resembles another
species in the Heath
family, American Wintergreen (
Gaultheria procumbens),
in appearance.
This latter species can be distinguished by its somewhat larger leaves
(1-2" long), the wintergreen aroma of its leaves when they are crushed,
the spicy flavor of its fruits, and the more pointed calyces of its
flowers. It produces solitary flowers from the leaf axils, rather than
clusters of 2-15 flowers from the tips of twigs. Another common name of
Arctostaphylos uva-ursi is Kinnikinnik. This was
originally an Amerindian name for
this shrub; its dried leaves were often used as an ingredient
in tobacco by them.