Thalictrum dasycarpum
purple meadow-rue [Blooms: May-Jun]
Purple meadow-rue (Thalictrum dasycarpum) flowers and fruits. (1) A male (staminate) inflorescence. With the individual stamens shimmering in the breeze, this was a stunning sight. (2) A single male flower that retains the five light green sepals. The stamens here have white filaments and yellow anthers; the anthers turn a tan color with age. (3) Two female flowers with obvious stout, white, fuzzy styles. The green structures at the base of the styles are the ovaries. (4) A female flower after fertilization. Although the styles remain, the ovaries have begun to swell. (5) Maturing seed pods of purple meadow-rue. The fruit is still green and bears the withered remnants of the styles but has begun to develop the longitudinal ribbing of the mature seed pod (which will be brown).
Purple meadow-rue is a native perennial that is listed as “vulnerable” in Illinois. The species is found in most of the lower 48 states in the U.S. but is notably absent from states on the Atlantic and Pacific coasts. (However, it is present along the Gulf of Mexico.) Purple meadow-rue is dioecious — some plants produce only staminate (male) flowers, each with around a dozen stamens; other plants bear only pistillate (female) flowers, each with about ten pistils. The male flowers are the showier of the two. Petals are absent (the plant is wind-pollinated). Both the narrow, whitish-grey, thread-like pistils and the yellow-green stamens (with pale yellow anthers) droop from 4-5 light green sepals (that may drop off). Fertilized female flowers develop a single, spindle-shaped fruit that is 1/4″ long, elongated, sharply pointed with a remnant style, 4-6 raised ribs, and slightly concave along one side. The fruit is initially green, turning brown with maturity. Early meadow-rue (Thalictrum dioicum) is similar to purple meadow-rue but has light purplish-green stems and leaves with 3-9 (typically five) rounded lobes and long petioles on the upper leaves.
Purple meadow-rue (Thalictrum dasycarpum) stems and leaves. Left: a purple, fuzzy stem of purple meadow-rue with one of the compound leaves’ leaf node. Right: a single purple meadow-rue compound leaf showing the upper side of the leaf in the upper image and the underside of the same leaf in the lower image. The three-lobed leaflets are characteristic.
Purple meadow-rue is tall (up to seven feet), and initially unbranched; the stems are (usually) purple, round in section, and either hairless or sparsely fuzzy with short hairs. The stem leaves are alternate, ternately compound, and up to two feet long and across with long petioles near the base of the stem, decreasing in size and petiole length higher on the stem, becoming sessile on the upper leaves. The leaflets are blue-green, sessile, 3/4-2″ long and 2/3 as wide, usually with 2-3 lobes with a distinct point at the tip; the margins of the leaflets are smooth and sometimes rolled under.
A male purple meadow-rue (Thalictrum dasycarpum) plant in Bobolink Meadow. The insert shows a magnified view of two male purple meadow-rue flowers. The white filaments and tan anthers of the stamens are apparent.
Purple meadow-rue is a native perennial that is listed as “vulnerable” in Illinois. The species is found in most of the lower 48 states in the U.S. but is notably absent from states on the Atlantic and Pacific coasts (however, it is present along the Gulf of Mexico). Purple meadow-rue is tall (up to seven feet), and initially unbranched; the stems are (usually) purple, round in section, and either hairless or sparsely fuzzy with short hairs. The stem leaves are alternate, ternately compound, and up to two feet long and across with long petioles near the base of the stem, decreasing in size and petiole length higher on the stem, becoming sessile on the upper leaves. The leaflets are blue-green, sessile, 3/4-2″ long and 2/3 as wide, usually with 2-3 lobes with a distinct point at the tip; the margins of the leaflets are smooth and sometimes rolled under. Purple meadow-rue is dioecious — some plants produce only staminate (male) flowers, each with around a dozen stamens; other plants bear only pistillate (female) flowers, each with about ten pistils. The male flowers are the showier of the two. Petals are absent (the plant is wind-pollinated). Both the narrow, whitish-grey, thread-like pistils and the yellow-green stamens (with pale yellow anthers) droop from 4-5 light green sepals (that may drop off). Fertilized female flowers develop a single, spindle-shaped fruit that is 1/4″ long, elongated, sharply pointed with a remnant style, 4-6 raised ribs, and slightly concave along one side. The fruit is initially green, turning brown with maturity. Early meadow-rue (Thalictrum dioicum) is similar to purple meadow-rue but has light purplish-green stems and leaves with 3-9 (typically five) rounded lobes and long petioles on the upper leaves.
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