This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
Flowers - Greenish white, the calyx of 4 or 5 sepals, falling early; no petals; numerous white, thread-like, green-tipped stamens, spreading in feathery tufts, borne in large, loose, compound terminal clusters 1 ft. long or more. Stem: Stout, erect, 3 to 11 ft. high, leafy, branching above. Leaves: Arranged in threes, compounded of various shaped leaflets, the lobes pointed or rounded, dark above, paler below.
Tall Meadow-Rue (Thalictrum polygamum)
Preferred Habitat - Open sunny swamps, beside sluggish water, low meadows.
Flowering Season - July - September.
Distribution - Quebec to Florida, westward to Ohio.
Masses of these soft, feathery flowers, towering above the ranker growth of midsummer, possess an unseasonable, ethereal, chaste, spring-like beauty. On some plants the flowers are white and exquisite; others, again, are dull and coarser. Why is this? Because these are what botanists term polygamous flowers, i. e., some of them are perfect, containing both stamens and pistils; some are male only; others, again, are female. Naturally an insect, like ourselves, is first attracted to the more beautiful male blossoms, the pollen bearers, and of course it transfers the vitalizing dust to the dull pistillate flowers visited later. But the meadow-rue, which produces a superabundance of very light, dry pollen, easily blown by the wind, is often fertilized through that agent also, just as grasses, plantains, sedges, birches, oaks, pines, and all cone-bearing trees are. As might be expected, a plant which has not yet ascended the evolutionary scale high enough to economize its pollen by making insects carry it invariably, overtops surrounding vegetation to take advantage of every breeze that blows.
The Early Meadow-rue (T. dioicum), found blooming in open, rocky woods during April and May, from Alabama northward to Labrador, and westward to Missouri, grows only one or two feet high, and, like its tall sister, bears fleecy, greenish-white flowers, the staminate and the pistillate ones on different plants. These produce no nectar; they offer no showy corolla advertisement to catch the eye of passing insects; yet so abundant is the dry pollen produced by the male blossoms that insects which come to feed on it must occasionally transfer some, albeit this primitive genus still depends largely on the wind. Not its flower, but the exquisite foliage resembling sprays of a robust maidenhair fern, is this meadow-rue's chief charm.
The Purplish Meadow-rue (T.purpurascens), so like the tall species in general characteristics that one cannot tell the dried and pressed specimens of these variable plants apart, is easily named afield by the purplish tinge of its green polygamous flowers. Often its stems show color also. Sometimes, not always, the plant is downy, and the comparatively thick leaflets, which are dark green above, are waxy beneath. We look for this meadow-rue in copses and woodlands from Northern Canada to Florida, and far westward after the early meadow-rue has flowered, but before the tall one spreads its fleecy panicles. Quite as decorative as the flower clusters are the compound seed-bearing stars.