Prairie Phlox
Phlox pilosa
Phlox family (Polemoniaceae)

Description: This herbaceous perennial plant is up to 2' tall and unbranched. The stem is covered with fine white hairs. The opposite leaves are up to 3" long and " across, and sparsely distributed along the stem. They are linear to narrowly lanceolate, sessile, and have smooth, but slightly ciliate margins. Their surface often has a fine pubescence. The lower leaves tend to turn yellow and drop off the stem when the plant becomes stressed out. There is a cluster of flowers at the apex of the plant on short hairy stalks. Each flower is about " across, and has 5 lobes that flare abruptly outward from a long narrow tubular corolla. These lobes are rather angular and become considerably more narrow toward the base of the corolla. The calyx has long slender sepals that are green and hairy. The flowers may be white, pink, or lavender, and have a mild pleasant fragrance. The base of the corolla often has lines of deeper color than the lobes. Prairie Phlox typically blooms during late spring or early summer for about 1–1 months. This plant has a taproot, and occasionally tillers at the base, sending up multiple stems. The small seeds are distributed by the wind to some extent.

Cultivation: The preference is full or partial sun, and moist to mesic conditions. The soil can consist of rich loam, clay loam, sandy loam, or have some rocky material. Foliar disease doesn't bother this phlox to any significant extent. It is difficult to start plants from seeds, but somewhat easier from transplants. Sometimes, Prairie Phlox can be temperamental and short-lived if a site doesn't suit its requirements.

Range & Habitat: The native Prairie Phlox occurs occasionally in most of Illinois, but is uncommon or absent in west central and southeastern Illinois (see Distribution Map). At high quality sites, it may be locally common. Habitats include moist to mesic black soil prairies, rocky open forests, Bur Oak savannas, sandy Black Oak savannas, limestone glades, thickets, abandoned fields, and prairie remnants along railroads. Prairie Phlox appears to benefit from the removal of excess debris by wildfires occurring during early spring or the fall.

Faunal Associations: The nectar of the flowers attracts primarily long-tongued bees, butterflies, and skippers. Other visitors include moths and bee flies. Among the bee visitors are bumblebees, Anthophorine bees, Miner bees, and Nomadine Cuckoo bees. Butterfly and skipper visitors include the American Painted Lady, Sulfurs, Swallowtails, and Cloudywings. The caterpillars of the moth Heliothis phloxiphagus (Spotted Straw) eat the flowers, while the caterpillars of the moth Olive Arches eat the leaves. Other insects feeding on this phlox and others include Lopidea davis (Phlox Scarlet Plant Bug) and Poecilocapsus lineatus (Four-Lined Plant Bug). Mammalian herbivores readily consume Prairie Phlox, including rabbits, deer, groundhogs, and livestock. It may be difficult to establish this plant where there is an overpopulation of these animals.

Photographic Location: The photographs were taken at the webmaster's wildflower garden in Urbana, Illinois.

Comments: The flower structure of the Phlox genus is a classical example of a butterfly flower. Such flowers feature flared petals that function as a landing pad for these insects, and a long narrow tube that is accessible to the long proboscis of butterflies, as well as skippers and moths. Such flowers typically occur in loose, rounded clusters, and are often fragrant. The flowers of Prairie Phlox have all of these characteristics. A very rare variety of Prairie Phlox that occurs within the Sangamon river basin in Sangamon and Champaign counties is Phlox pilosa var. sangamonensis (Sangamon Phlox). It is distinguished primarily by its hairless stems, flowering stalks, and leaves, and is listed as an endangered species in the state of Illinois.