Characteristics of Horsetails Structure and Morphology The stem is green, rigid, ribbed, and can be simple or whorled. It is jointed (composed of nodes and internodes) and usually hollow. The leaves are scale-like, arranged in whorls along the branches, and fused into toothed brown sheaths. Each plant produces 5-10 sporangia, which develop on the inner … Читати далі Field Horsetail (Equisetum arvense)