Each stem terminates in a spike-like raceme of purple flowers about ¾-4" in length. The central stalk of the raceme is light green to purplish green and glabrous. Each flower is about ¼" long and across when it is fully open, consisting of 3 petals, 5 sepals, several inserted stamens, and a pistil with a single style. Two sepals are enlarged, rosy pink to purple, and petaloid, forming a pair of lateral wings. The remaining three sepals are smaller in size, light green to purple, and ovate in shape. The 3 petals form a fringed tubular structure that surrounds the stamens and style; they are rosy pink to purple, often becoming more white toward their tips. The short glabrous pedicels of the flowers are light green to purple, slender, and often nodding. Sometimes a few cleistogamous (self-fertile) flowers develop toward the base of the raceme; they are bud-like and inconspicuous. The blooming period occurs from early to mid-summer and lasts about 3 weeks. Only a few flowers are in bloom at the same time. Afterwards, they are replaced by 2-celled seed capsules; each cell of a capsule contains a single hairy seed. In addition to the above-ground flowers, Purple Milkwort also produces cleistogamous flowers along underground stems. The root system consists of a taproot.
Common Milkwort is a native, perennial, scrambling, patch-forming, low herb, growing up to 30cm.
The small flowers (4-7mm) are purple, blue, pink or white, in short spikes.
Individual flowers have a corollary tube made up of 3 joined petals; an upper entire petal and 2 frilly lower petals. The corollary tube contains 8 stamens.
The flower also has 2 large, coloured, petaloid sepals (like wings) and 3 small green sepals.
Leaves are dark green, slightly fleshy and ribbed.