This herbaceous perennial plant is ¾–2½' tall and either unbranched or
branching occasionally above. The erect central stem (and any lateral
stems) is light green to reddish yellow and sharply 4-angled; usually
there are short hairs along the angles of the stem, otherwise it is
glabrous. Pairs of opposite leaves occur along the stem(s) at
moderately to widely spaced intervals; each successive pair of
leaves rotates 90º from the preceding pair of leaves. The leaves are
1–2¼" long and ½–¾" across; they are oblong-lanceolate to oblong-ovate
in shape, while their margins are crenate or crenate-serrate. Both the
upper and lower leaf surfaces are yellowish green to medium green; the
upper surface is glabrous to sparsely short-pubescent, while the lower
surface is glabrous to short-hairy along the major veins. The upper
leaf surface is conspicuously indented where the primary and secondary
veins occur. The leaf tips are short-acute to acute, while the leaf
rounded or slightly cordate; the leaves are either sessile or they have
very short petioles. The foliage does not have a noticeable aroma.
Solitary flowers (rarely pairs of flowers) develop from the axils of
the middle to upper leaves on short pedicels up to 4 mm. (1/6") long.
The 2 flowers for each pair of leaves are often perpendicular to the
orientation of their leaves, facing in the same direction.
is about ¾–1" long, consisting of a tubular 2-lipped corolla, a short
2-lipped calyx, 4 inserted stamens, and an ovary with an inserted
style. The corolla is ascending, becoming wider toward its
outward-facing lips; it is predominately blue, becoming whitish toward
its base and inside its throat. The upper lip forms a skull-shaped
hood, while the lower lip forms a broad landing pad for flower-visiting
insects. The exterior of the corolla (especially above) has short fine
pubescence. The calyx is light green to yellowish red and finely
pubescent; on its upper side, there is an oblique dish-shaped
appendage. The blooming period occurs from mid- to late summer, lasting
about 1-2 months. There is no noticeable floral scent. Afterwards, each
flower is replaced by a small capsule containing up to 4 nutlets; this
capsule eventually splits open, ejecting the nutlets. The root system
is fibrous and stoloniferous, often forming small colonies of clonal
preference is full sun to light shade, wet conditions, and soil
containing sand, muck, or peaty material. Shallow water is readily
tolerated. This plant could be cultivated in wetland gardens.
Range & Habitat:
The native Marsh Skullcap is occasional in northern and west-central
Illinois, while in the rest of the state it is absent (see Distribution
). Illinois lies along the southern range-limit of this
Marsh Skullcap also occurs in Eurasia; it is usually found in boreal
regions. Habitats include marshes, sandy marshes, borders of small
ponds or slow-moving streams, peaty bogs, openings in swamps, wet
thickets, ditches. These habitats often occur in sandy areas. This
plant is found in higher quality natural areas.
Like other skullcap species (Scutellaria spp.
flowers of this plant are probably cross-pollinated by long-tongued
bees. The endangered Karner Blue Butterfly (Lycaeides melissa
) and probably other butterflies also visit the
but they are less effective at cross-pollination. Larvae and adults of
the leaf beetles, Phyllobrotica limbata
feed on Marsh Skullcap; this plant is reportedly the favorite
host of the latter leaf beetle. Some species of micromoths, including Prochoreutis
(Skullcap Skeletonizer Moth), also feed on the leaves of skullcaps
(Grundel & Pavlovic, 2000; Clark et al, 2004; Panzer et al.,
Because Marsh Skullcap has bitter foliage and it occurs in relatively
inaccessible locations, it is probably not browsed to any significant
extent by mammalian herbivores.
A sandy marsh at Illinois
Beach State Park in NE Illinois.
Marsh Skullcap has fairly showy flowers. It can be distinguished from
other skullcap species (Scutellaria spp.
in Illinois by the following combination of features: 1) only solitary
axillary flowers are produced, rather than terminal racemes of flowers,
2) the flowers exceed ½" in length, 3) the leaves are fairly narrow in
shape (less than 1" across), and 4) it is found in wetlands, rather
than drier areas of woodlands and prairies. The common name,
'skullcap,' for this group of wildflowers may refer to the shape of
the upper lip of their flowers. A scientific synonym of Marsh Skullcap
is Scutellaria epilobiifolia