motherwort (Leonurus cardiaca)
SCIENTIFIC SYNONYMS: There are no scientific synonyms for
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name of motherwort
is Leonurus cardiaca L. Motherwort is one of many introduced members
of the Mint Family with small tubular flowers. It has foliage with a some-
what distinctive appearance and flowers that are exceptionally hairy.
Motherwort belongs to large group of plants in the Mint Family that pro-
duce nonterminal whorls of flowers above the opposite leaves; other
groups in this large family produce terminal racemes and spikes, or non-
terminal flowers that aren't whorled. The petioles of the motherwort are
longer than the flowers, and its leaves have wedged-shaped bottoms and
3-5 cleft lobes with pointed tips. Other species in the Mint Family have
petioles that are shorter than the flowers, or their leaves have rounded bot-
toms and unlobed margins. Leonurus cardiaca is the only species of the
Leonurus genus reported as inhabiting Facquier County.
NATIVE STATUS: Introduced, United States and Canada.
GENERAL BOTANTICAL CHARACTERISTICS:
Habit: This introduced perennial plant is 2-5' tall and sparingly branched
below the inflorescence. The stems are 4-angled, heavily ridged, and slight-
Leaves: The opposite leaves are variable in size and shape, although they
all have long petioles that are slightly pubescent. The lower leaves often
have 5 cleft lobes and several coarse teeth; they are up up to 4" long and
3" across. The middle leaves have 3 cleft lobes and a few coarse teeth;
they are up to 3" long and 1½" across. The upper leaves are often oblong-
ovate with a pair of coarse teeth; they are up to 2" long and ¾" across.
These leaves are nearly hairless and have conspicuous veins along the up-
per surface. The base of each leaf is more or less wedge-shaped. The stems
of motherwort are normally erect, although older plants toward the end of
the growing season have a tendency to sprawl.
Flowers: Whorls of sessile flowers occur above the axils of the opposite
leaves on the middle to upper stems. Each tubular flower is 2-lipped and
about 1/3" long. The corolla is white or light pink and quite hairy on the
upper side; these fuzzy white hairs exceed 1 mm. in length. The upper lip
is undivided, while the lower lip has a central lobe and 2 smaller side lobes.
There are usually purple dots on the lower lip and near the throat of the
corolla. The tubular green calyx has 5 lanceolate teeth; it is slightly pub-
escent. These teeth are sharp-pointed and persistent. While the flowers are
not noticeably fragrant, the foliage has a slightly rank odor.
Fruits/Seeds: Each flower is replaced by 4 nutlets that are 3-sided and red-
dish brown or brown.
Roots: The root system consists of shallow fibrous roots and rhizomes.
This plant spreads by reseeding itself and vegetatively by means of the
rhizomes; it often forms colonies.
REGENERATION PROCESS: Motherwort propogates by reseeding
itself and vegetatively by means of the rhizomes.
HABITAT TYPES: Motherwort was introduced into the United States
from Europe as an herb with medicinal properties (motherwort is origi-
nally from central Asia). Habitats include open disturbed woodlands,
areas along woodland paths, woodland borders and thickets, edges of
degraded wetlands, edges of yards underneath trees, and partially shaded
fence rows. While motherwort normally occurs in disturbed areas, it can
also invade higher quality woodland areas. This plant is still sold by
commercial nurseries as a medicinal herb.
SITE CHARACTERISTICS: Motherwort prefers partial sun and
moist fertile soil. If the soil becomes too dry, the lower leaves have a
tendency to fall off and the entire plant may wilt or die. Plants are at-
tractive while young, but become ragged in appearance with age.
SEASONAL DEVELOPMENT: The blooming period occurs during the
summer and lasts about 2 months.
GENERAL DISTRIBUTION: Motherwort is found throughout most
of the states of the United States (Florida and California excepted), and
all the southern provinces of Canada (Newfoundland and the northern
terrorties have reported the occurrence of motherwort).
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: The flowers are pollinated by bumble-
bees and other long-tongued bees, including little carpenter bees and
Anthophorine bees; these insects are attracted by nectar primarily.
Syrphid flies and Halictid bees are attracted to the pollen of the flowers,
but they are less effective pollinators. Occasionally the foliage is attacked
by Tetranychus urticae (two-spotted spider mite), which is polyphagous.
Mammalian herbivores avoid the foliage as a food source because it is
bitter-tasting and probably slightly toxic. It is possible that the seeds are
transported by mammals because the spine-like teeth of the calyx can
cling to fur (or clothing).
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