Nightshade family (Solanaceae)
This herbaceous plant is a summer
annual in temperate climates, while
in tropical climates it is usually a perennial. The growth form is
usually a sprawling indeterminate vine about 3-8' long, although short
determinate plants less than 3' long may remain erect. As a vine, this
plant will sprawl across the ground, unless it is trained along a wire
cage, trellis, or fence; it can also be tied to a stake in some cases.
The stems branch occasionally; they are light green to purplish green,
more or less
terete, and glandular short-pubescent. In addition, spreading
hairs may be scattered across the stems. Alternate compound leaves
occur along these stems that are widely spreading; they are 4-18" long
and 2-6" across. These compound leaves are odd-pinnate with 3-5 pairs
of lateral (or primary) leaflets and a terminal leaflet. Interspersed
between the lateral leaflets are smaller secondary leaflets.
The petioles of the compound leaves are 1-4" long, light green to
purplish green, and glandular short-pubescent; they also may have
scattered spreading hairs.
The lateral leaflets are 1¼-3" long and about one-half as much
across; they are ovate or lanceolate in shape, coarsely dentate or
along their margins, and sometimes shallowly cleft. The terminal
leaflet is slightly larger in size than the lateral leaflets, otherwise
it is similar in appearance. The
secondary leaflets are up to ½" long and at least one-half as much
across; they are ovate or oval in shape, while their margins
are sparingly dentate, crenate, or entire (smooth).
The bases of lateral leaflets are often oblique (asymmetric). The upper
leaflet surfaces are medium green and sparsely
glandular short-pubescent (appearing almost glabrous), while the lower
leaflet surfaces are pale green and moderately glandular
short-pubescent. The rachises and petioles of these compound leaves are
light green and glandular short-pubescent. In addition, they may have
scattered spreading hairs. The petiolules (basal stalklets) of the
lateral and terminal leaflets are up to ¾" long, light green, and
glandular short-pubescent. The secondary leaflets are sessile, or they
have even shorter basal stalklets. Occasionally, short racemes of 3-15
flowers up to 4" long develop from the axils of the compound leaves.
Each flower is about ½" across, consisting of a short calyx with 5
linear teeth, a yellow corolla with 5 spreading to strongly recurved
lobes, a column of 5 united stamens, and a pistil with a single style.
The calyx is light green and glandular short-pubescent; it may
have a few spreading hairs. The lobes of the corolla are narrowly
deltate (triangular) and they are longer than the teeth of the calyx.
The peduncle and pedicels of the raceme are light green, glandular
short-pubescent, and often crooked; they also may have scattered
The blooming period occurs from early summer into autumn, lasting
several months (for indeterminate seed-started
plants). Some flowers will fail to set fruits; they are self-fertile to
some extent, but fruit-set is better with either hand- or
insect-pollination. The fruits are berries ranging from ½" to 4"
across; wild plants usually produce smaller fruits. These fruits are
subgloboid, globoid, broadly ellipsoid, or pyriform
(pear-like) in shape with shiny smooth skin; young
fruits are glandular short-pubescent, but they become more
glabrous with age. Immature fruits are light green or whitish green,
but they become yellow, orange, or red (usually the latter) at
maturity. The peduncles, pedicels, and calyx teeth of these fruits
become enlarged as they mature. The interior of mature fruits is
fleshy, juicy, and slightly tart-sweet; numerous seed-bearing
cavities are scattered throughout the interior (although smaller fruits
will have fewer seed-bearing cavities). Individual seeds are 2.0-3.5
mm. long and about one-half as much across; they are light tan,
flattened-obovoid in shape, smooth-sided, and finely pubescent along
their margins. The light seeds are sometimes distributed by wind or
water. This plant reproduces by reseeding itself.
The preference is full sun, moist to
mesic conditions, and fertile
loamy soil. Partial sun and less fertile soil is tolerated, but fruit
set will be smaller. Tomato plants are vulnerable to a variety of
disease organisms; different cultivars vary in their disease
resistance. Cultivars also vary significantly in the size of plants and
the size of fruits that they produce, which can affect the
characteristics of escaped plants.
& Habitat: As a
naturalized plant that has escaped cultivation, the Tomato is scattered
across Illinois and it is relatively uncommon (see Distribution
wild plants rarely persist for more than 1-2 years. The Tomato was
introduced into North America from South America. It is widely
cultivated for its edible fruits both commercially and in gardens of
residential areas. Naturalized habitats include fallow fields, areas
around gardens, banks of creeks and drainage canals, gravel and mud
bars in streams, roadsides, areas along railroads, and waste places.
Disturbed areas are preferred. This cultivated plant is not invasive.
The flowers are cross-pollinated by
bees, and possibly other bees. The floral reward is pollen. Insects
that feed destructively on tomato plants include several species of
leaf beetles (including Epitrix
clavata, & Psylliodes
stink bugs (including Euschistus
spp.), an aphid (Rhopalosiphoninus
solani), the Garden Fleahopper (Halticus bractatus),
caterpillars of a Noctuid moth, the Tomato Fruitworm (Helicoverpa zea),
and caterpillars of two sphinx moths, the Tobacco Hornworm (Manduca sexta) and
Tomato Hornworm (Manduca
quinquemaculata). Various mammals probably
feed on the fruits, but these records are incomplete. The Cottontail
Rabbit sometimes nibbles on the foliage of young plants when they are
less toxic, and during hot dry summer weather they sometimes gnaw on
ripened fruits to gain access to their moisture. There is also some
evidence that the Snapping Turtle (Cheldyra
serpentina), Eastern Box
carolina), and Ornate Box Turtle (Terrapene ornata)
like to feed on the ripened fruits (Ernst et al., 1994; Lagler, 1943).
Similar to other berry-producing species in the Nightshade family,
tomato seeds can probably pass through the gullets of such animals and
viable. As a result, these animals may spread the seeds of this plant
to new areas. The foliage and immature green fruits are more or less
toxic from the alkaloids solanine and tomatine. Thus their consumption
is usually avoided by most vertebrate animals.
Along an alley in Urbana, Illinois.
Because we consume the edible berries of the Tomato, they should be
considered a fruit, rather than a vegetable, as the latter term
typically refers to the edible leaves, stalks, or roots of various
plants. Tomato fruits are widely consumed throughout the world and they
are used in a variety of culinary dishes, including salads, stews, and
sauces. The fruits contain such beneficial substances as beta-carotene
(the precursor to Vitamin A), Vitamin C, potassium, and the
anti-oxidant lycopene. It is relatively easy to identify naturalized
plants in the wild, especially when they are in the fruit-bearing
stage. Because of the glandular pubescence on the foliage and young
fruits, tomato plants have a distinctive aroma.