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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.

Thalictrum

Thalictrum dasycarpum

purple meadow-rue [Blooms: May-Jun]

Early meadow-rue's main stem terminates in a panicle up to a foot long and wide; each branch in the panicle has a corymb of about five flowers at its tip. Early meadow-rue is dioecious — some plants produce only staminate (male) flowers, each with 10+ stamens; other plants bear only pistillate (female) flowers, each with up to 15 pistils. Both male and female flowers droop from their stems, but the male flowers have a longer droop than do the female flowers. Both male and female flowers are about 1/2" long and 1/4" across with 4-5 pale green sepals with white margins (which often fall off). Neither male nor female flowers have petals; pollination is via the wind. Fertilized female flowers produce ellipsoid, dry seeds that are pointed at both ends; the surface bears strong ribbing. Early meadow-rue prefers shady woodlands. It has more lobes on its leaves (usually 3-5), and the lobes are more rounded than purple meadow-rue (Thalictrum dasycarpum), the other Thalictrum species in Jackson Park, does (2-3 pointed lobes).

Thalictrum

Thalictrum dioicum

early meadow-rue [Blooms: Apr-May]

Stinging nettle plants are dioecious (unisexual) with male (staminate) and female (pistillate) flowers on separate plants. Flowers occur in knobby clusters (panicles) that arise from the leaf axils. Neither pistillate nor staminate flowers have any petals. Staminate flowers have four light green, identical sepals cupping four short stamens. Pistillate flowers also have four sepals but two are narrowly lance-shaped, about a millimeter long, and free, alternating with two sepals that are 1.4-1.8 mm long and cupped around the ovary; styles are absent but the single stigma is long and feathery. The fruit is a flattened, oval to egg-shaped seed, less than 1/16" long.

Urtica

Urtica dioica

stinging nettle [Blooms: Jul-Aug]

Riverbank grape's flowers develop in 5" long, drooping, cylindrical or pyramidal panicles opposite the leaves of new branches (but skipping every third leaf). The flowers are greenish-yellow and are best described as skeletal; they may be either unisexual or (rarely) perfect (both male and female reproductive organs functional). The male and female unisexual flowers usually both occur on the same plant, either in separate or mixed clusters; both male and female flowers are 1/8" across or less, with a minute calyx and five green to yellowish petals that quickly fall off. Male flowers have five very long, pale, erect stamens around a button-like center; female flowers have an ovary with a short style and five short, sterile stamens, often contorted. The fruit are .... grapes — a round berry, 1/4-1/2" across containing 1-4 seeds, initially green but turning blue-black as it matures, often with a white bloom on the skin. You know, grapes. The fruit of riverside grape is often sour until after a frost, then becomes more "sweet/tart" to the tongue. Riverside grape is subject to parasitism by the grape filbert gall midge (Ampelomyia vitiscoryloides), an insect whose larvae produce large, very hairy, conical galls at leaf nodes. This gall midge is restricted to the eastern half of North America; it was first described by Alpheus Spring Packard, Jr. in 1869.

Vitis

Vitis riparia

riverbank grape [Blooms: [May-Jun]