Gentian family (Gentianaceae)
Description: This native perennial plant is 1-2' tall. Multiple stems can emerge from the taproot, otherwise this plant is unbranched. The central stem is round, hairless, and either light green or purple. The opposite leaves are up to 4½" long and 2" across, and sessile against the stem. They are broadly lanceolate or ovate, with smooth margins and parallel venation. The upper surface of each leaf is dark green and often shiny, while both the upper and lower surfaces are devoid of hairs. The uppermost tier of leaves is often whorled. The apex of the stem terminates in a cluster of flowers immediately above the whorled leaves, while smaller clusters of flowers may develop from the axils of the upper pairs of leaves. These flowers are bottle-shaped, looking like oversized flowerbuds even when mature, and they are 11½" long. The corollas are violet, and will assume different shades of this color depending on the maturity of each flower. There are longitudinal ridges along the outer edge of the corolla, providing it with a wrinkly appearance. The corolla remains closed at the top even when the flower is ready to receive pollinating insects. Inside, the reproductive structures of the flower are fused together to form a central column. The corolla usually has 5 lobes, but these are barely noticeable because of an interconnecting fringe that is even taller than the lobes. The green calyx is much smaller than the corolla, and divided into 5 lanceolate segments. These segments may curl outward away from the flower rather than remaining upright. The blooming period can occur from late summer to early fall, and usually lasts about a month. There is no noticeable floral scent. The small seeds can be transported by water or wind some distance from a mother plant. The root system consists of a stout taproot. Vegetative reproduction does not normally occur.
Cultivation: The preference is full or partial sun, and moist rich soil. It is easier to start with potted plants rather than seed, as germination can be erratic and seedling mortality can be high. Mature plants are rarely bothered by foliar disease or leaf-chewing insects. The worst threat is droughty conditions, but appropriate placement of plants will mitigate this problem.
Range & Habitat: Bottle Gentian is occasional in the northern half of Illinois, and uncommon in the rest of the state. However, populations of the plant are probably declining as a result of the destruction of wetlands. Habitats include moist black soil prairies, openings in floodplain forests, thickets, fens, and swampy areas near bodies of water. This plant often occurs in calcareous soil.
Faunal Associations: Bumblebees are the primary pollinators of the flowers, as they are one of the few insects that can force their way past the closed corolla. This floral characteristic excludes smaller insects that are less efficient at pollination from robbing nectar and pollen from the bumblebees. Because the foliage and roots are bitter-tasting, mammalian herbivores usually don't use this plant as a food source. However, deer may chomp off the tender tops of the plants before they have a chance to flower. This can cause the central stem to form smaller side branches. The seeds are too small to be of much interest to birds. The ecological value of Bottle Gentian is low, notwithstanding the appeal of the flowers to humans.
Comments: Bottle Gentian is a wierd-looking plant with a striking appearance. The adorable flowers are often deep violet, although other shades also occur, even in the same cluster of flowers (as illustrated in the upper photo). The only other gentian that this species can be confused with (among those that occur in Illinois) is Gentiana saponaria (Soapwort Gentian). Usually, Soapwort Gentian is pale violet or greyish blue, while the interconnecting fringe of the corolla is shorter than, or equal to, the length of the lobes. This interconnecting fringe is always taller than the lobes in the corolla of the Bottle Gentian. Sometimes the segments of the calyx curve outward in the Bottle Gentian, while they remain reasonably upright in the Soapwort Gentian, but this is not always a reliable distinction.