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 - Dull or greenish yellow, small, without involucre or in-volucels; borne in 7 to 15 rayed umbels, 2 to 6 in. across. Stem: 2 to 5 ft. tall, stout, smooth, branching, grooved, from a long, conic, fleshy, strong-scented root. Leaves: Compounded (pinnately), of several pairs of oval, lobed, or cut, sharply toothed leaflets; the petioled lower leaves often 1 1/2 ft. long.
Preferred Habitat - Waste places, roadsides, fields.
Flowering Season - June - September.
Distribution - Common throughout nearly all parts of the United States and Canada. Europe.
Men are not the only creatures who feed upon such of the umbel-bearing plants as are innocent - parsnips, celery, parsley, carrots, caraway, and fennel, among others; and even those which contain properties that are poisonous to highly organized men and beasts, afford harmless food for insects. Pliny says that parsnips, which were cultivated beyond the Rhine in the days of Tiberius, were brought to Rome annually to please the emperor's exacting palate; yet this same plant, which has overrun two continents, in its wild state (when its leaves are a paler yellowish green than under cultivation) often proves poisonous. A strongly acrid juice in the very tough stem causes intelligent cattle to let it alone - precisely the object desired. But caterpillars of certain swallow-tail butterflies, particularly of the common eastern swallow-tail (Papilio asterias), may betaken on it - the same greenish, black-banded, and yellow-dotted fat "worm" found on parsnips, fennel, and parsley in the kitchen garden. Insects understood plant relationships ages before Linnaeus defined them. When we see this dark, velvety butterfly, marked with yellow, hovering above the wild parsnip, we may know she is there only to lay eggs that her larvae may eat their way to maturity on this favorite food store. After the flat, oval, shining seeds with their conspicuous oil tubes are set in the spreading umbels, the strong, vigorous plant loses nothing of its decorative charm.
From April to June the lower-growing Early or Golden Meadow Parsnip (Zizia aurea) spreads its clearer yellow umbels above moist fields, meadows, and swamps from New Brunswick and Dakota to the Gulf of Mexico. Its leaves are twice or thrice compounded of oblong, pointed, saw-edged, but not lobed leaflets.
The Hairy-jointed Meadow Parsnip (Thaspium barbinode), another early bloomer, with pale-yellow flowers, most common in the Mississippi basin, may always be distinguished by the little tufts of hair at the joints of the stem, the compound leaves, and often on the rays of the umbels.
A yellow variety of the purple meadow parsnip, which is popularly known as Golden Alexanders (T. trifoliahim var. aureum), confines itself chiefly to woodlands. The leaves are compounded of three leaflets, longer and more lance-shaped in outline than those of other yellow species.