Apple
Malus pumila
Rose family (Rosaceae)
Description:
This small
tree is typically 15-50' tall, forming a short crooked trunk
about 1-2½' across and a globoid crown with spreading crooked branches.
Trunk bark is reddish gray, thin, and irregularly fissured, while
branch bark is more gray and smooth. Twigs are reddish brown to brown
with scattered white lenticels; they are glabrous or pubescent. Young
shoots are light gray-green to purple, terete, and densely pubescent.
Alternate
leaves about 2-3½" long and 1¼-2¼" across occur along the twigs and
young shoots. The leaf blades are lanceolate-ovate to ovate in shape
and finely serrated or crenulated
along their margins. The upper surface of the leaf blades is yellowish
green to dark green and hairless (or nearly so), while the lower
surface is pale gray-green or whitish green and more or less downy from
short fine hairs. The petioles are ¾-1½" long, whitish green to
dull purple, and downy from short fine hairs. Bases of the leaf
blades are rounded or slightly cordate, while their tips are blunt to
pointed.
Relatively large flowers about 1¼-2" across are produced in
small clusters from short spur twigs. Individual flowers have 5 rounded
petals that are pinkish white to white and contracted at their bases, 5
lanceolate sepals that are pale gray-green and downy from short fine
hairs, numerous stamens (about 20) with yellow anthers, and an inferior
ovary with 5 styles. The sepals
are much smaller than the petals. The slender pedicels are pale
gray-green and downy from short fine hairs. The blooming period occurs
during late spring for about 2 weeks (after the vernal leaves have
unfolded). The flowers are fragrant. Fertile flowers are replaced by
small green pomes that develop during the summer. At maturity during
late summer or fall, the pomes are 1½-4" across and more or less
globoid in shape; each pome has a depression at its top and bottom. The
exterior of mature pomes is usually greenish red or red (rarely yellow)
and glabrous or nearly so; sometimes short fine hairs occur within the
depressions of each pome. The fleshy interior of mature pomes is
greenish white to pale yellow, crisp, and somewhat juicy; the
flavor can be sour, sweet-sour, or sweet. Within the central portion of
each pome, there are up to 10 brown seeds. These small seeds
are ovoid and flattened. The deciduous leaves usually
turn yellow during the autumn.
Cultivation:
The preference is
full sun, moist to mesic well-drained conditions, and fertile
loamy soil. The cultivated Apple is vulnerable to many insect pests and
disease organisms, although some cultivars have greater resistance to
them than others. Dwarf cultivars are available that produce full-sized
fruit on trees less than 10' tall.
Range
& Habitat: As a
naturalized tree, the non-native Apple is occasional in NE Illinois and
uncommon elsewhere (see Distribution
Map). It was introduced from
Eurasia into North America. Habitats for naturalized trees include
woodland borders, disturbed meadows, abandoned orchards and old
homesteads, areas along roads, and fence rows. Apple is
often cultivated for its large edible fruit and it is used as an
ornamental landscape tree. When it escapes from cultivation, Apple is
not aggressive and invasive. The fruits of escaped trees are usually
smaller than those of cultivated trees. Apple is vulnerable to
wildfires.
Faunal
Associations: The flowers must be
cross-pollinated by insects from other compatible trees, otherwise
Apple does not set fruit. Bees are the most important visitors of the
flowers, where they seek nectar or pollen. Typical bee visitors include
honeybees, bumblebees, Andrenid bees (Andrena spp.),
long-horned bees
(Synhalonia spp.),
and mason bees (Osmia
spp.). Other insects eat the
foliage, suck plant juices, bore through the wood, or feed
destructively on the fruit and flowers. The caterpillars of the
following butterflies occasionally eat the leaves of Apple and other
Malus spp.:
Limenitis archippus
(Viceroy), Limenitis
arthemis astyanax
(Red-Spotted Purple), Papilio
glaucus (Tiger Swallowtail), and Satyrium
liparops strigosum (Striped Hairstreak). The caterpillars
of many moths
also feed on these shrubs and small trees; they include such species as
Choreutis pariana
(Apple & Thorn Skeletonizer), Malacosoma
americanum (Eastern Tent Caterpillar), Orthosia hibisci
(Speckled Green
Fruitworm), Phyllonorycter
crataegella (Apple Blotch Leafminer), and
Sphinx gordius
(Gordian Sphinx). See the Moth Table for a
more complete
list of species. Larvae of the long-horned beetles Saperda candida
(Round-Headed Apple Tree Borer) and Saperda cretata
(Spotted Apple Tree
Borer) bore through the wood of these trees, as do larvae of
the Buprestid
beetle Chrysobothris
femorata (Flat-Headed Apple Tree Borer). Other
insect feeders include Anthonomus
quadrigibbus (Apple Curculio),
Conotrachelus nenuphar
(Plum Curculio), and Rhynchaenus
pallicarnis
(Apple Flea Weevil); Aphis
pomi (Green Apple Aphid), Dysaphis
plantaginea (Rosy Apple Aphid), Eriosoma lanigerum
(Woolly Apple
Aphid), and Rhopalosiphum
insertum (Apple Grain Aphid); Typhlocyba
pomaria (White Apple Leafhopper) and other leafhoppers; Ceresa bubalus
(Buffalo Treehopper) and other treehoppers; Lygidea mendax
(Apple Red
Bug) and other plant bugs; Acrosternum
hilaris (Green Stink Bug) and
other stink bugs; and Rhagoletis
pomenella (Apple Maggot). See the
Insect Table for a
more complete list of these species. In addition to
these insects, another invertebrate feeder is Aculus schlechtendali
(Apple Rust Mite).
Some vertebrate animals also use Apple trees as a
food source. Their buds are eaten by the Ruffed Grouse, Purple Finch,
and White-Throated Sparrow, while their fruits are eaten by the Black
Bear, White-Tailed Deer, Red Fox, Opossum, Striped Skunk, and the
introduced Monk Parakeet. The Cottontail Rabbit and Meadow Vole gnaw on
the bark of saplings during the winter, occasionally girdling and
killing them. White-Tailed Deer like to browse on the leaves and twigs
of Apple trees, particularly those of smaller and more vulnerable
trees. Mammals that eat the fruits can spread the seeds into new
locations. Humans also spread the seeds when they throw apple cores out
of car windows or toss them aside along paths in natural areas.
Occasionally, the Apple and other Malus
spp. provide nesting habitat
for such birds as the Yellow-Breasted Chat, Song Sparrow, and Orchard
Oriole.
Photographic
Location: A small tree along a sidewalk in Urbana,
Illinois.
Comments:
This is the domesticated Apple tree that
occasionally escapes from
cultivation. In the published literature and on the internet, a
confusing variety of scientific names refer to this tree:
Malus
communis, Malus
domestica, Malus
pumila, Malus
sylvestris, and Pyrus
malus. Of these, Malus
pumila is the preferred scientific name for
both cultivated and naturalized Apple trees. Because
naturalized
trees may hybridize with other Malus
spp. (Crab Apples), identification
of wild trees can be difficult, particularly around urban and suburban
areas. In general, Apple has larger fruits (1½" across or more) than
Crab Apples. It also has leaves that are short-pubescent on
their
undersides and they lack lateral lobes. The native Crab Apples have
smaller greenish yellow fruits and their leaves are often shallowly
lobed. Another cultivated species that sometimes escapes, Malus baccata
(Siberian Crab Apple), also has smaller fruits and its leaf undersides
are hairless.