Description: The fertile shoots of this native perennial plant are about 1–1½' tall and unbranched, except near the apex where the flowers occur. The central stem of each fertile shoot is green to reddish brown and pubescent to hairy; some of these hairs are sticky-glandular. Occasionally, 1-2 short side stems are produced from the axils of the upper leaves. The opposite leaves of the fertile shoots are up to 3" long and 1" across; they are triangular-lanceolate to lanceolate and pubescent or hairy. The margins of the leaves are smooth and ciliate, while at the base they are sessile or clasp the stem. In addition to the fertile shoots, Woodland Phlox also produces infertile shoots that fail to produce flowers. These infertile shoots have a similar appearance to the fertile shoots, except that their stems are somewhat shorter and their leaves are more rounded at the tips. These infertile shoots tend to be less hairy as well.
Each upper stem of the fertile shoots
terminates in an unbranched cluster of flowers. Each flower spans about
¾–1" across. It consists of a pale blue-violet or lavender corolla
with 5 spreading petals that are fused together at its tubular base, and a
hairy green or reddish green calyx with 5 teeth that are long and narrow. The
throat of the corolla is very narrow; the stamens with their yellow anthers are
inserted within the throat. The spreading petals (or lobes) are narrow toward
the throat of the corolla, but become broader toward their tips. The tips of
these petals are well-rounded, slightly pointed, or slightly indented; they are
never deeply indented or cleft. The pedicel of each flower is rather short and
hairy. The blooming period occurs during late spring to early summer and lasts
about a month. The floral scent is pleasantly sweet and aromatic. Each flower
is replaced by a seed capsule containing several seeds. The root system
consists of a taproot and above-ground stolons that establish the infertile
shoots. Small clumps of plants are often formed by means of these
stolons.
Cultivation: The preference
is light shade to partial sun, moist to slightly dry conditions, and a rich
loamy soil with abundant organic matter. The fertile shoots die down after
seeds have been produced, but the infertile shoots remain green for the
remainder of the growing season.
Range &
Habitat: Woodland Phlox is a common plant that occurs in nearly all
counties of Illinois; it is somewhat less common in the NW area of the state
(see
Distribution
Map). Habitats include moist to slightly dry deciduous woodlands and areas
along woodland paths. In young woodlands that have sprung up where the original
woodland was destroyed by plowing or heavy construction, this species is
usually absent. It can survive minor, but not severe, degradation of woodland
habitat. Removal or thinning of dense stands of Sugar Maple saplings is
beneficial because it improves ambient light levels for the infertile
shoots.
Faunal Associations: The
flowers are pollinated by long-tongued bees (especially bumblebees), bee flies,
butterflies (especially swallowtails), skippers, and moths (including Sphinx
& Hummingbird moths). These insects suck nectar from the flowers. Some
insects feed on Phlox spp. (Phloxes), including Lopidea davisi
(Phlox Plant Bug; damages buds & flowers), Heliothis phloxiphagus
(Spotted Straw; caterpillars feed on flowers), and Lacinipolia olivacea
(Olive Arches; caterpillars feed on foliage). The latter two species are moths.
The foliage of Woodland Phlox is readily consumed by various mammalian
herbivores, including rabbits, deer, and livestock.
Photographic Location: Busey Woods in Urbana,
Illinois. Woodland Phlox is usually found in mesic areas of this deciduous
woodland.
Comments: The flowers of
Woodland Phlox often have a wonderful fragrance and it is a beautiful plant.
Compared to other Phlox spp. (Phloxes), its flowers are more blue-violet
and less pink in color. However, there is some variation in the color of the
flowers across different areas. Woodland Phlox is readily distinguished from
other Phloxes by the shape of its flowers: The lobes (or petals) of the corolla
are more narrow toward the center of the flower than at their tips. These
swollen tips are well-rounded, slightly pointed, or slightly indented; they are
never deeply cleft like Phlox bifida (Sand Phlox). The leaves of
Woodland Phlox are usually broader than the leaves of other Phloxes, especially
those that prefer sunny areas. This is also one of the few Phlox species with
sterile shoots that never produce flowers; instead, they store energy in the
roots for the production of next year's fertile shoots and
flowers.