Plants to 1 m, prostrate to sometimes erect; lvs green, the principal ones mostly 4–10 cm, usually deltoid-hastate and irregularly toothed above the lobes; infls of loose glomerules forming a terminal thyrse, leafy-bracteate throughout; fruiting bracteoles spongy-thickened toward the base, obscurely veined, mostly 5–13 mm, united nearly to the middle, ovate-triangular to rhombic-triangular, abruptly acuminate, the lateral angles rounded, with a few small teeth or entire, the back often roughened; brown seeds 2.5–4 mm wide; black seeds smaller, 1.5–2.5 mm wide, or wanting; radicle median, ascending; diploid on x=9. Sea beaches; Nf. and Que. to R.I., and widespread on the Atlantic coast of Europe, whence probably intr. (A. patula ssp. g.)
A herb. It lies along the ground. It can grow 20-100 cm high. The branches are opposite. The stems are green and striped. The leaves are 1-10 cm long by 1-8 cm wide. The seeds can be black or brown. They are 3-4 mm wide.