The slender greenish-brown stems become reddish brown in fall with a zig-zagging character. An aide to identification, the stems have decurrent ridges evident between the nodes. Pairs of stipular prickes, 1/8 - 1/2" long, are evident at the nodes on stems of plants that are reasonably vigorous. The more vigorous the plant, the larger the prickles. Stems of mature, slow-growing plants may not have these prickles.