Description: This native perennial plant is
2–3' tall and little branched, except near the apex. The central stem is
4-angled and finely pubescent. The opposite leaves are up to 3½" long
and 1½" across. They are ovate, crenate along the margins, and have
short petioles. The undersides of the pubescent leaves have conspicuous veins,
along which are longer white hairs. From the upper leaf axils, short secondary
stems with smaller leaves may form. The upper stems terminate in spike-like
racemes of blue-violet flowers. These racemes are held upright and have
densely-spaced pairs of flowers. Each tubular flower is about ¾" long
and angles upward from its base. The upper lip is hoodlike and has recurved
margins, while the lower lip is larger and broader, with a conspicuous patch of
white near the throat of the flower. A very fine pubescence covers the surface
of the flower, although it is hard to see. The whitish green calyx and pedicels
are also finely pubescent. None of these hairs are glandular nor sticky. The
blooming period is from mid- to late summer, and lasts about 1½ months.
There is no floral scent. The flowers are replaced by a skullcap-shaped
structure containing the nutlets. The root system consists of a taproot, and
occasionally produces rhizomes.
Cultivation: The preference is partial sun and mesic
to dry conditions. Full sun or light shade and moist conditions are also
tolerated. The soil can contain fertile loam or some rocky material, which
corresponds to the conditions in which this plant normally grows. Foliar
disease rarely bothers this plant; some of the lower leaves may turn yellow and
drop off the stem if there is a severe drought, but this member of the mint
family withstands dry conditions rather well. Occasionally, insects may chew
holes in some of the leaves. This plant is easy to grow.
Range & Habitat: Downy Skullcap occurs
occasionally in the southern half of Illinois, and is largely absent elsewhere
(see
Distribution
Map). Habitats include rocky upland forests, thinly wooded bluffs, rocky
slopes along rivers, upland meadows in woodland areas, thickets, and wooded
roadsides. This plant usually occurs in and around rocky upland forests, but
occasionally strays into adjacent meadows. It blooms later and tolerates more
sunlight than most Skullcap species.
Faunal
Associations: The flowers are pollinated by bumblebees primarily,
which suck nectar or collect pollen. Less common visitors are bee flies,
skippers, or small butterflies, but these visitors are less likely to pollinate
the flowers. Some species of wasps may perforate the base of the flower and
steal nectar (specifically, the Eumenid wasp Euodynerus foraminatus has
been observed to do this), and Halictid bees sometimes take advantage of these
perforations to suck nectar themselves. Because the foliage is bitter-tasting
and possibly mildly toxic, mammalian herbivores usually don't bother this plant
to any significant degree.
Photographic
Location: The photographs were taken at the webmaster's wildflower
garden in Urbana, Illinois. By moving the mouse cursor over the upper
photograph, a close-up of the flowers will be revealed.
Comments: Downy Skullcap has attractive foliage and
flowers. It is similar to Agastache foeniculum (Anise Hyssop) in the
appearance of its foliage and habitat preferences, but the tubular flowers are
larger and more attractive. Therefore, it's surprising that this plant is not
grown in flower gardens more often. Downy Skullcap tolerates full sunlight
quite well in my experience, and its potential as a prairie or woodland meadow
plant has been underestimated, in part because the prairie restoration movement
is dominated by organizations in northern Illinois, Wisconsin, and other areas
where this plant does not occur. Distinguishing Scutellaria spp. is
rather tricky, but here are some key characteristics of Downy Skullcap: 1)
Except for the lowest leaves, the leaf bases are well-rounded to wedge-shaped,
rather than heart-shaped; 2) This species of Skullcap blooms later and grows
taller than most; 3) Except for the upper leaf surfaces, the entire plant is
finely pubescent (i.e., canescent), and it has no sticky glandular hairs; and
4) The racemes of flowers are terminal, rather than
axillary.