Mazus pumilus is an annual herb, lax, to 15 cm hairy, often with several stems.
Leaves opposite, mostly in basal rosette, blade spatula-shaped 1-4 cm long,0.5-1.5 cm wide, often purplish below, margin with a few coarse teeth, stem leaves alternate, smaller.
Flowers blue-violet with yellow and white markings, to 1 cm long, bilaterally symmetrical, tubular, 2-lipped, upper lip 2-toothed, lower lip 3-toothed, much longer, calyx 5-parted, 0.4-0.5 cm, becoming0.9 cm in fruit; inflorescence a raceme of 4-10 flowers, solitary in axils of alternate bracts (Radford et al. 1968); blooms and fruits May-Nov.
Fruit a small capsule, shorter than calyx, splitting open at top to release very small seeds. Seed dispersal apparently by raindrop splash in open capsule (Nakanishi 2002).
Wetland status: FACU-.
Frequency in NYC: Very infrequent.
Habitat: Open areas. Rarely escapes from cultivation.
Notes: Young, cooked leaves apparently edible. Also has been used medicinally (Fern 2004).