Carrot family (Apiaceae)
Description: This herbaceous perennial plant is 1-2½' tall, branching sparingly in the upper half of the plant. The stems are hairless and round, with light green lines that run vertically. The basal leaves are undivided, up to 4" long and 3" across, and have petioles about 2-3" long. They are usually cordate or broadly ovate in overall shape, but with blunt or rounded tips. Otherwise, the leaves alternate up the stem, having progressively shorter petioles and a smaller size. The upper leaves are often ternately compound, and sometimes each leaflet is divided into three lobes. The surface of these leaves are often shiny, while their margins are serrate or crenate. There may be a purplish spot where the petiole meets the base of a leaf.
The upper stems produce compound umbels of tiny yellow flowers. A typical umbel spans about 2-3" across, and consists of about 7-15 umbellets, which in turn have about 10-20 flowers. These flowers have short pedicels, except the central flower of each umbellet, which is sessile. Each flower has 5 yellow petals that barely open, and is less than 1/8" across. The blooming period occurs during late spring and lasts about a month. There is no noticeable floral scent. Each flower is replaced by a small fruit with 5 angular ribs – however, this fruit is not winged. The root system consists of a central taproot.
Cultivation: This plant prefers light shade to full sun, and mesic to dry conditions. The soil can contain loam, clay-loam, or some rocky material. This plant is easy to grow, and not much troubled by foliar disease.
Range & Habitat: The native Heartleaf Golden Alexanders is restricted to NE Illinois, where it is an uncommon plant (see Distribution Map). It also occurs in Hardin county of SE Illinois. Habitats include moist to dry black soil prairies, hill prairies, rocky upland woodlands, limestone glades, bluffs, abandoned fields, and roadsides. Usually, this species occurs in drier locations than Zizia aurea (Golden Alexanders).
Faunal Associations: Various kinds of insects visit the flowers primarily for nectar, especially small bees (Halictid, Andrenid, Nomadine) and flies (Chloropid, Tachinid, Muscid, Syrphid, etc.), as well as occasional beetles and plant bugs. The bees collect pollen as well, while some flies and beetles may feed on pollen. The caterpillars of Papilio polyxenes asterias (Black Swallowtail butterfly) feed on the foliage of this and other members of the Carrot family.
Photographic Location: The photographs were taken at the wildflower garden of the webmaster in Urbana, Illinois.
Comments: Heartleaf Golden Alexanders differs from its close relative, Zizia aurea (Golden Alexanders), by its simple basal leaves, while the latter species has lower leaves that are compound. It also closely resembles Thaspium trifoliatum var. aureum (Meadow Parsnip), but differs from this species in two ways: 1) The central flower of each umbellet is sessile, and 2) the angular fruits enclosing the seeds lack wings. The central flower of each umbellet for the Meadow Parsnip, on the other hand, has a short pedicel like the other flowers, and its angular fruits are strongly winged and somewhat flattened. These latter characteristics provide the Meadow Parsnip with a slight advantage in the distribution of its seeds by wind.