Phlox divaricata laphamii
Phlox family (Polemoniaceae)
Description: The fertile shoots of this herbaceous 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 light 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 2½" long and ¾" across; they are narrowly lanceolate to ovate and sparsely short-pubescent to 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 do not produce flowers. These infertile shoots have a similar appearance to the fertile shoots, except that their stems are somewhat shorter and their leaves tend to have more rounded tips.
Each upper stem of a fertile shoot terminates in a cluster of flowers spanning 2-3½" across. Each flower spans about 1" across. It consists of a light blue-violet, lavender, or white corolla with 5 spreading lobes that are fused together at its tubular base, and a hairy green or reddish green calyx with 5 linear teeth. The throat of the corolla is very narrow; the 5 stamens and pistil are inserted within. The spreading lobes are narrow toward the throat of the corolla, but become broader toward their tips (oblanceolate). For this subspecies of Woodland Phlox (Phlox divaricata laphamii), the tips of these lobes are rounded or bluntly angular; they are never deeply indented or cleft. The pedicels of the flowers are rather short and hairy. The blooming period occurs from mid-spring to early summer and lasts about a month. The floral scent is pleasantly sweet and aromatic. Each flower is replaced by an ovoid seed capsule (4 mm. in length) containing several small seeds. The root system produces stolons that establish infertile shoots. Small colonies of clonal plants are often formed by means of these stolons.
Cultivation: The preference is light shade to partial sun, moist to dry-mesic 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: This native subspecies of Woodland Phlox (Phlox divaricata laphamii) 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 Hummingbird Clearwing & Sphinx moths). These insects suck nectar from the flowers. Some insects feed on Phlox spp. (Phlox species), 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 browsed 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. (Phlox species), the flowers of this subspecies of Woodland Phlox are more blue-violet and less pink in color. However, there is some variation in the color of the flowers across different areas. This subspecies of Woodland Phlox (Phlox divaricata laphamii) has corolla lobes with rounded or bluntly angular tips. In contrast, the typical subspecies of Woodland Phlox (Phlox divaricata divaricata) has corolla lobes with shallowly notched tips. The corolla lobes of these subspecies are never deeply cleft like those of Phlox bifida (Sand Phlox). The leaves of Woodland Phlox are usually more broad than the leaves of other Phlox species, especially those that prefer sunny areas. This is also one of the few Phlox species that produces clumps of infertile shoots. These infertile shoots store energy in the roots for the early production of next year's fertile shoots and flowers.