This wildflower is a herbaceous perennial about 1-2' tall.
stem and any lateral stems are light green to reddish green, 4-angled,
and glabrous. Pairs of sessile opposite leaves occur along these stems.
Individual leaves are 1-2½" long and ½-1½" across; they are lanceolate
to ovate and dentate along their margins. The elongated teeth of the
margins have narrow tips that bend toward the tip of each leaf blade.
The upper surface of each leaf is medium green and glabrous;
appearance because of the indentations along its veins.
The lower surface of each leaf is pale to medium green and either
glabrous or nearly so. The foliage of Spearmint has a moderately strong
minty fragrance. The central stem and any upper lateral stems terminate
in dense spikes of whorled flowers about 1-6" long. At the apex of the
central stem, the inflorescence typically consists of a central spike
and 2 smaller lateral spikes. Individual flowers are about 1/8" (3 mm.)
consisting of a short tubular calyx with 5 narrow teeth, a short
tubular corolla with 5 lobes, 4 strongly exerted stamens, and a pistil
with a single style that is divided at its tip. The calyx is light
green to reddish green and glabrous, while the corolla is white to
light pink. The blooming period occurs from mid-summer into fall,
lasting about 1-2 months. Afterwards, each flower is replaced by 4
small nutlets that are located within the persistent calyx. The shallow
root system is fibrous and rhizomatous. Clonal colonies of plants
are often produced from the rhizomes.
preference is full or partial sun, moist conditions, and soil
consisting of fertile loam. Spearmint can spread aggressively in open
areas where there is limited competition from taller plants. Sometimes
it is adversely affected by rust-related foliar disease.
Spearmint is occasional in scattered
throughout Illinois (see Distribution
). Spearmint was introduced into North America
from Europe as a medicinal and culinary herb, but it
from cultivation and naturalized in mainly disturbed habitats. These
habitats include low areas along rivers, damp weedy meadows, roadside
ditches, areas along the foundations of buildings, edges of yards, and
vacant lots. Spearmint is often cultivated in gardens.
Generally, the flowers of Spearmint and
other Mentha spp.
(mints) attract nectar-seeking small bees, wasps, flower flies
(Syrphidae) and other flies, the Cabbage Butterfly (Pieris rapae
other small butterflies, and skippers. Other insects feed on the
foliage and other parts of mints. This latter group includes the
caterpillars of such moths as Agriopodes
(The Gray Marvel),
(LeConte's Haploa), Pyrausta
(Mint-Loving Pyrausta), and Sphinx
(Hermit Sphinx). Other insect feeders include the
and the stink bug Coenus
animals largely avoid mints as a food source, although the Ruffed
Grouse reportedly eats their leaves (Bennetts, 1900).
A low area along a drainage ditch
Among the various Mentha
(mints) and their hybrids, Spearmint
makes one of the better-flavored mint teas. Spearmint flavoring is also
used in chewing gum and other products; it has significant economic
importance. Spearmint has been widely cultivated since ancient times,
and was introduced to the British Isles by the Romans. Distinguishing
the various mints and their hybrids is often rather difficult.
Spearmint can be identified by its hairless stems and leaves, the lack
of petioles on its leaves, the wrinkled appearance of its leaves, the
pleasant mint fragrance of its leaves, and its terminal spikes of
flowers. Other mints tend to be more hairy, their leaves usually have
petioles and they are less wrinkled in appearance, their leaves
may not have a pleasant mint fragrance, or their flowers may
occur in axillary whorls above the leaves.