This is very common on my plot, germinating any time, spring or summer, and managing to grow and look healthy on the driest of soils with no water for months now. It forms a mat to start with on bare soil, but will romp up and through other plants given a chance. The flowers are in inconspicuous bunches in leaf axils (in flower now), and the seeds are rounding black and shiny (and abundant). It forms a strong tap root that is pink in colour; that colour may pervade the stems to various degrees.
