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 - Small, white, on slender pedicels from leaf axils, also in terminal clusters. Calyx (usually) of 5 sepals, much longer than the 5 (usually) 2-parted petals; 2-10 stamens; 3 or 4 styles. Stem: Weak, branched, tufted, leafy, 4 to 6 in long, a hairy fringe on one side. Leaves: Opposite, acutely oval, lower ones petioled, upper ones seated on stem.
Flowering Season - Throughout the year.
Distribution - Almost universal.
The sole use man has discovered for this often pestiferous weed with which nature carpets moist soil the world around is to feed caged song-birds. What is the secret of the insignificant little plant's triumphal progress? Like most immigrants that have undergone ages of selective struggle in the Old World, it successfully competes with our native blossoms by readily adjusting itself to new conditions, filling places unoccupied, and chiefly by prolonging its season of bloom beyond theirs, to get relief from the pressure of competition for insect trade in the busy season. Except during the most cruel frosts, there is scarcely a day in the year when we may not find the little star-like chickweed flowers. Contrast this season with that of a native chickweed, the Long-leaved Stitchwort (A. longifolia), blooming only from May till July, when competition is fiercest! Also, the common chickweed has its parts so arranged that it can fertilize itself when it is too cold for insect pollen-carriers to fly; then, especially, are many of its stamens abortive, not to waste the precious dust. Yet even in winter it produces abundant seed. In sunny, fine spring weather, however, when so much nectar is secreted the fine little drops may be easily seen by the naked eye, small bees, flies, and even thrips visit the blossoms whose anthers shed pollen one by one before the three stigmatic surfaces are ready to receive any from younger flowers.