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 - Yellow, 1/4. to 1/2 in. across, growing singly on long peduncles from the leaf axils. Five petals longer than the 5 acute calyx lobes with 5 linear bracts between them; about 20 stamens; pistils numerous, forming a head. Stem: Spreading over ground by slender runners or ascending. Leaves: 5-fingered, the digitate, saw-edged leaflets (rarely 3 or 4) spreading from a common point, petioled; some in a tuft at base.
Preferred Habitat - Dry fields, roadsides, hills, banks.
Flowering Season - April - August.
Distribution - Quebec to Georgia, and westward beyond the Mississippi.
Every one crossing dry fields in the eastern United States and Canada at least must have trod on a carpet of cinquefoil (cinque =five, feuilles=leaves), and have noticed the bright little blossoms among the pretty foliage, possibly mistaking the plant for its cousin, the trefoliate barren strawberry (see p. 203). Both have flowers like miniature wild yellow roses. During the Middle Ages, when misdirected zeal credited almost any plant with healing virtues for every ill that flesh is heir to, the cinquefoils were considered most potent remedies, hence their generic name.
The Shrubby Cinquefoil, or Prairie Weed (P. fructicosa), becomes fairly troublesome in certain parts of its range, which extends from Greenland to Alaska, and southward to New Jersey, Arizona, and California, as well as over northern Europe and Asia. It is a bushy, much branched, and leafy shrub, six inches to four feet high, with bright yellow, five-parted flowers an inch across, more or less, either solitary or in cymes at the tips of the branches. They appear from June to September. The honey-bee, alighting in the centre of a blossom and turning around, passes its tongue over the entire nectar-bearing ring at the base of the stamens, then proceeding to another flower to do likewise, effects cross-fertilization regularly. On a sunny day the bright blossoms attract many visitors of the lower grade out after nectar and pollen, the beetles often devouring the anthers in their greed. The leaves on this cinquefoil are usually compounded of one terminal and four side leaflets that are narrowly oblong, an inch or less in length, and silky hairy. Sometimes there may be seven leaflets pinnately, not digitately, arranged. Although the shrubby cinquefoil prefers swamps and moist, rocky places to dwell in, it wisely adapts itself, as globe-trotters should, to whatever conditions it meets.
Silvery or Hoary Cinquefoil (P. argentea), found in dry soil, blooming from May to September from Canada to Delaware, Indiana, Kansas, and Dakota, also in Europe and Asia, has yellow flowers only about a quarter of an inch across, but foliage of special beauty. From the tufted, branching, ascending stems, four to twelve inches long, the finely cleft, five-foliate leaves are spread on foot stems that diminish in size as they ascend, not to let the upper leaves shut off the light from the lower ones. These leaves are smooth and green above, silvery on the under side, with fine white hairs, adapted for protection from excessive sunlight and too rapid transpiration of precious moisture. They entirely conceal the sensitive epidermis from which they grow.