Zizia aptera
heartleaf alexanders [Blooms: Apr/May–?]
Heartleaf alexanders (Zizia aptera) flowers. Right: a compound umbel of immature heartleaf alexanders flowers. The petals are tightly furled, and the stamens remain hidden beneath the petals. Left: a compound umbel of mature heartleaf alexanders flowers. The long stamens are deployed, extending well past the margins of the petals. The petals remain loosely furled.
The tips of the upper stems of heartleaf alexanders produce 2-3″ wide compound umbels of 7-15 umbellets, each with 10-20 tiny yellow flowers. The central flower of each umbellet is sessile; the rest have short pedicels (a diagnostic character of the genus). Each 1/8″ wide flower consists of five yellow petals that remain curled, five stamens with yellow anthers projecting through the spaces between the petals, and two styles. The fruits are a ribbed capsule with a flat top from which the remnants of the styles project. Heartleaf alexanders is restricted to northeastern Illinois, where it is uncommon; it is usually found in drier habitats than its much more common relative, golden alexanders (Zizia aurea).
Heartleaf alexanders (Zizia aptera) stems and leaves. Top right: a heartleaf alexanders plant viewed from the side. Both the heart-shaped basal leaves (B) and the more oval stem leaves (S) are visible. Top left: another lateral view of a heartleaf alexanders plant. Basal leaves (B) are visible at the bottom right; stem leaves (S) with long petioles coming off a robust stem are visible on the left.
Heartleaf alexanders (aka, heart-leaved alexanders) is a native perennial 1-2.5 feet tall. The stems are round in section and hairless, with light green lines running parallel to the stem; branches are few and restricted to the upper half of the plant. The basal leaves are simple (undivided), up to 4″ long and 3″ wide, glossy, heart-shaped or oval with blunt or rounded tips, finely serrated margins, and 2-3″ long petioles; the main veins radiate out from near the point where the petiole joins the blade. Lower and middle stem leaves are alternate and similar to the basal leaves in shape but become progressively smaller and with shorter petioles higher on the stem. There is often a purple spot or a purple section at the base of the short leaf midrib where it joins the petiole. The upper stem leaves are often trifoliate compound, sometimes with each leaflet itself divided into three lobes; the two lateral leaflets are nearly sessile while the apical leaflet has a petiolule about half the length of the leaflet.
A heartleaf alexanders (Zizia aptera) plant on the west side of West Lagoon. looking down on the plant. Note the heart-shaped oval basal and stem leaves with veins radiating from the tip of the petiole.
Heartleaf alexanders (aka, heart-leaved alexanders) is a native perennial 1-2.5 feet tall. The stems are round in section and hairless, with light green lines running parallel to the stem; branches are few and restricted to the upper half of the plant. The basal leaves are simple (undivided), up to 4″ long and 3″ wide, glossy, heart-shaped or oval with blunt or rounded tips, finely serrated margins, and 2-3″ long petioles; the main veins radiate out from near the point where the petiole joins the blade. Lower and middle stem leaves are alternate and similar to the basal leaves in shape but become progressively smaller and with shorter petioles higher on the stem. There is often a purple spot or a purple section at the base of the short leaf midrib where it joins the petiole. The upper stem leaves are often trifoliate compound, sometimes with each leaflet itself divided into three lobes; the two lateral leaflets are nearly sessile while the apical leaflet has a petiolule about half the length of the leaflet. The tips of the upper stems produce 2-3″ wide compound umbels of 7-15 umbellets, each with 10-20 tiny yellow flowers. The central flower of each umbellet is sessile; the rest have short pedicels (a diagnostic character of the genus). Each 1/8″ wide flower consists of five yellow petals that remain curled, five stamens with yellow anthers projecting through the spaces between the petals, and two styles. The fruits are a ribbed capsule with a flat top from which the remnants of the styles project. Heartleaf alexanders is restricted to northeastern Illinois, where it is uncommon; it is usually found in drier habitats than its much more common relative, golden alexanders (Zizia aurea).
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