Description:
This medium-small tree is typically 30-60' tall, forming a short stout
trunk up to 3' across and a rounded crown that is densely branched.
Trunk bark of mature trees is grayish brown or reddish brown,
consisting of narrow irregular strips that are separated by very
shallow furrows. Branch bark and twigs are brown, reddish brown, or
gray and more smooth; the twigs have scattered white lenticels. Young
shoots are light green and either glabrous or pubescent (usually the
former). Alternate leaves occur abundantly along the twigs and
shoots; both the leaves and shoots contain a thin milky sap. Individual
leaves are 3-6" long, 2½-4" across, and their margins are
serrated. Some leaves are ovate or oval-ovate in
shape and unlobed, while other leaves are similar in outline, but
moderately divided into 2-5 lobes (typically a terminal lobe and 1-2
lateral lobes, rarely 2 additional basal lobes). Unlobed leaves are
more common than lobed leaves. The leaves taper abruptly into narrow
tips, while their bases are cordate or rounded. The upper leaf surface
is medium to dark green and usually rough-textured from minute stiff
hairs, while the lower leaf surface is light green, pubescent along the
veins, and short-pubescent between the veins. At the base of each leaf,
there are 2 prominent lateral veins and a prominent central vein.
Additional lateral veins are arranged pinnately along the central vein
of each leaf. The petioles are up to 1½" long, light green, and either
glabrous or finely pubescent (usually the former, except for very young
leaves).
Red Mulberry (
Morus rubra)
is usually dioecious (male and
female flowers on separate trees), although less often it is monoecious
(male and female flowers on the same tree). The male (staminate)
flowers occur in drooping catkins about 1½-2" long. Each male flower
consists of 4 light green sepals and 4 stamens; there are no petals.
The sepals are oblong in shape and joined together toward the base;
they are finely pubescent. The female (pistillate) flowers occur in
catkins about 1" long; the female flowers are arranged densely
together. Each female flower consists of 4 light green sepals and a
light green ovary with a pair of stigmata; there are no petals. The
sepals
are oblong or elliptic and finely pubescent; they are joined together
at the base. The peduncles of the catkins are about ¼-1" long, light
green, and finely pubescent; the rachises (central stalks) of the
catkins are also light green and pubescent. The blooming period occurs
from mid- to late spring, lasting about 1-2 weeks. The flowers are
cross-pollinated by the wind. Afterwards, female catkins become
transformed into compound drupes that are berry-like in appearance.
Each compound drupe consists of numerous single-seeded drupelets. As
the compound drupes mature, they change color from light green, to red,
and finally to nearly black. Mature compound drupes are about ¾-1½" in
length and short-cylindrical in shape; at this time (typically during
early to mid-summer), they are juicy and sweet. Mature drupes remain on
a tree for only a short time before falling to the ground. The woody
root system is shallow and spreading. The deciduous leaves turn yellow
during the autumn.
Cultivation:
This tree can be cultivated in full sun to light shade, moist
conditions, and different kinds of soil, including those that contain
loam, clay, silt, and sand. A wide range of soil pH is tolerated.
Growth and development are relatively fast; individual trees can
bear fruit in as little as 10 years and they may live as long as
125 years. Leafspot disease organisms sometimes disfigure the foliage.
The seeds can be planted outdoors during autumn, or they can be
subjected to cool moist stratification for 30-90 days and planted
during the spring.
Range
& Habitat: The native Red Mulberry
(
Morus rubra)
is occasional throughout most of Illinois, except in the
NW section of the state, where it is uncommon (see
Distribution
Map).
Its range extends across the eastern half of the United States. For
poorly understood reasons, populations of this tree appear to be
declining as it used to be common. Habitats include floodplain
woodlands, woodland borders, wooded valleys, limestone glades, and
fence rows. Sometimes this tree is found in city parks and other
landscaped areas, but it is not often cultivated. Exposure to fire
usually kills this tree, possibly because of its thin bark or shallow
roots. To a greater extent than the similar
Morus alba (White
Mulberry), Red Mulberry is found in natural areas with intermediate or
low levels of disturbance. It usually occurs as widely scattered trees,
rather than forming colonies.
Faunal Associations: Red Mulberry
provides a source of food for various insects, birds, and mammals.
Among insects, the leaves are eaten by
Corythucha ciliata
(Sycamore
Lace Bug),
Parthenolecanium
corni (European Fruit Lecanium),
Pseudococcus comstocki (Comstock
Mealybug), and
Pulvinaria
innumerabilis (Cottony Maple Scale). In addition, the
larvae of several
long-horned beetles are known to bore through the wood or bark of this
tree: these species include
Euzophera
semifuneralis (American Plum
Borer),
Dorcaschema
wildii (Mulberry Borer),
Dorcaschema alternata
(Small Mulberry Borer),
Dorcaschema
cinerea,
Megacyllene
caryae
(Painted Hickory Borer), and
Parelaphidion
incertum (Mulberry Bark
Borer). The early-maturing fruits of this tree are an important source
of food to many kinds of birds, including the Wood Duck, Catbird,
Eastern Kingbird, Great Crested Flycatcher, Robin, Starling, and
Baltimore Oriole (see
Bird Table). In
addition, such mammals as the
Opossum, Raccoon, Fox Squirrel, and Gray Squirrel eat the fruits, as
does the Eastern Box Turtle (
Terrapene
carolina). By eating the fruits,
these vertebrate animals spread the seeds to new locations. The
Groundhog sometimes devours the seedlings of mulberry, while the Beaver
eats the bark and wood of more mature trees when they occur near bodies
of water.
Photographic Location: Along a stream in a floodplain
woodlands at
Springfield, Illinois.
Comments:
Compared to White Mulberry (
Morus
alba), which was
introduced from Asia into North America for an incipient silkworm
industry, the Red Mulberry (
Morus
rubra) is a more shade-tolerant
forest tree that is not often encountered in urban and suburban areas.
Red Mulberry tends to be a larger tree that is more densely branched,
its leaves are less often lobed, and its fruits are longer. The
maturation sequence of its fruits causes them to change color from
light green, to red, to nearly black. In contrast, the typical variety
of White Mulberry has fruits that remain white at maturity, while the
fruits of another variety (
var.
tartarica) of this tree has fruits
that change color from white, to red, to nearly black. Red Mulberry can
also be identified by the pubescence on the undersides of its leaves
(both along the veins and between them) and by the rough texture of its
leaf upper sides. In contrast, White Mulberry usually has leaves that
are
glabrous and smooth on both of their sides. In some areas, these two
mulberry species may hybridize, producing trees that have intermediate
characteristics. The wood of Red Mulberry is relatively light, soft,
and weak; it is not important commercially. However, it has been used
in the past to make fence posts, farm implements, furniture, interior
finish, and caskets.