Scleranthus annuus, commonly known as German knotweed or annual knawel, is an annual or biennial herb that is native to a variety of habitats including grasslands, open woodlands, and rocky slopes in Europe, Asia, and North Africa. It typically grows to a modest height of up to 6 inches (15 centimeters) and forms dense, mat-like patches. The plant has tiny, inconspicuous green flowers that may go unnoticed, blooming from late spring to early autumn. Its foliage is bright green and needle-like, adding a fine texture to garden settings.

German knotweed is valued for its low-growing, ground-covering habit, which makes it useful for filling gaps in rock gardens, green roofs, and as a living mulch to suppress weeds. It thrives in poor, sandy, or rocky soils with good drainage and prefers full sun to part shade. Annual knawel is not commonly affected by diseases or pests, but it can self-seed prolifically, which may lead to unwanted spread in the garden. It is potentially invasive outside its native range, so it is important to check local regulations before planting.CC BY-SA 4.0