Pennaceous feather Pennaceous feather The pennaceous feather is a type of feather present in most modern birds and in some other species of maniraptoriform dinosaurs. A pennaceous feather has a stalk or quill. Its basal part, called a "calamus", is embedded in the skin. The calamus is hollow and has pith formed from the dry remains of the feather pulp, and the calamus opens below by an "inferior umbilicus" and above by a "superior umbilicus". The stalk above the calamus is a solid "rachis" having an umbilical groove on its underside. Pennaceous feathers have a rachis with "vanes" or "vaxillum " spreading
Acorus calamus widely and frequently used herbal medicines among the Chipewyan people. The Potawatomi people powdered the dried root and placed this up the nose for catarrh. This plant is sometimes used as a pond plant in horticulture. There is at least one ornamental cultivar known; it is usually called 'Variegatus', but the RHS recommends calling it 'Argenteostriatus'. Both triploid and tetraploid "A. calamus" contain alpha-asarone. Other phytochemicals include: Diploids do not contain beta-asarone (β-asarone). The calamus has long been a symbol of love. The name is associated with a Greek myth: Kalamos, son of the river-god Maeander, who loved the youth