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 - Numerous, very small, variable; bright magenta, pink, or almost red, or pale to whiteness, or greenish, clustered in a globular clover-like head, gradually lengthening to a cylindric spike. Stem: 6 to 15 in. high, smooth, branched above, leafy. Leaves: Alternate, narrowly oblong, entire.
Preferred Habitat - Fields and meadows, moist or sandy.
Flowering Season - June - September.
Distribution - Southern Canada to North Carolina, westward to the Mississippi.
When these bright clover-like heads and the inconspicuous greenish ones grow together, the difference between them is so striking it is no wonder Linaeeus thought they were borne by two distinct species, sanguinea and viridescens, whereas they are now known to be merely two forms of the same flower. At first glance one might mistake the irregular little blossom for a member of the pea family; two of the five very unequal sepals - not petals - are colored wings. These bright-hued calyx-parts overlap around the flower-head like tiles on a roof. Within each pair of wings are three petals united into a tube, split on the back, to expose the vital organs to contact with the bee, the milkwort's best friend.
Plants of this genus were named polygala, the Greek for much milk, not because they have milky juice - for it is bitter and clear - but because feeding on them is supposed to increase the flow of cattle's milk.
In sandy swamps, especially near the coast from Maine to the Gulf, and westward to the Mississippi, grows the Marsh or Cross-leaved Milkwort (P. cruciata). Most of its leaves, especially the lower ones, are in whorls of four, and from July to September its dense, bright purple-pink, white, or greenish flower-heads, the wings awn-pointed, are seated on the ends of the square branching stem of this low, mossy little plant.