False Rue Anemone
Buttercup family (Ranunculaceae)
Description: This native perennial plant is up to 1' tall, branching sparingly. It produces both basal and alternate compound leaves with a similar appearance. The stems are reddish green, hairless, and slender. The compound leaves are trifoliate and they have slender petioles. The terminal leaflet has a longer petiolule (a stalk at its base) than the two lateral leaflets. These leaflets are up to 1" long and ¾" across. They are ternately lobed, cleft, and hairless.
The white flowers occur individually or in groups of 2-3. Each flower spans about ¾" across, consisting of 5 petal-like sepals that are white, no petals, several slender stamens with yellow anthers, and a few green pistils in the center. The blooming period occurs during mid-spring and lasts about 3 weeks. Each fertilized pistil is replaced by a beaked follicle (seedpod that splits open along one side) that contains several seeds. The root system is fibrous and occasionally small tubers are produced. Vegetative clones of the mother plant are often produced from these tubers; reproduction also occurs by the seeds. False Rue Anemone often forms dense colonies of plants.
Cultivation: The preference is partial sun to medium shade, slightly moist to mesic conditions, and a rich loamy soil with abundant leaf mould.
Range & Habitat: False Rue Anemone is fairly common in the majority of counties of Illinois, otherwise it is uncommon or absent (see Distribution Map). It typically occurs in mesic deciduous woodlands as one of the spring wildflowers. This species can be extirpated from a woodlands by an invasion of Alliaria petiolata (Garlic Mustard).
Faunal Associations: Except for visitors of the flowers, little is known about the floral-faunal relations of this species. The floral pollen attracts small bees and flies primarily, including Halictid bees, Andrenid bees, Little Carpenter bees, Syrphid flies, and other flies. The bees collect pollen, while the flies feed on pollen. Occasionally various beetles also feed on the pollen, but they are less effective at pollination. Some of these insects probably search in vain for nectar, as the flowers lack nectaries (see Melampy & Heyworth, 1980).
Photographic Location: A mesic deciduous woodlands at Busey Woods in Urbana, Illinois.
Comments: Another scientific name for False Rue Anemone is Isopyrum biternatum. This species blooms a little earlier than many other spring wildflowers in a woodlands, and it has attractive flowers and foliage. Two other members of the Buttercup family that occur in woodlands, Anemone quinequefolia (Wood Anemone) and Anemonella thalictroides (Rue Anemone), resemble False Rue Anemone. Wood Anemone has leaflets that are coarsely serrated along the margins and their lobes taper to sharp points; it also differs from False Rule Anemone by the whorl of leaves underneath the flowers. Rue Anemone also has whorled leaves underneath the flowers, otherwise its foliage is very similar to that of False Rue Anemone (which has alternate leaves along the stems). While Wood Anemone and Rue Anemone produce small clusters of beaked achenes (each containing a single seed within a hardened exterior), False Rue Anemone produces small clusters of beaked follicles that each contain 2 or more seeds. Sometimes the white flowers of Wood Anemone and Rue Anemone have more than 5 petal-like sepals, while the flowers of False Rue Anemone never have more than 5 petal-like sepals.