divided into five parts; specifically, having each floral whorl consist of five (or a multiple of five) members
pentamerous详细解释
pen.tam.er.ous adj.（形容词）Having five similar parts.有五个相似部分的Having flower parts, such as petals, sepals, and stamens, in sets of five, as in the geranium.五个一组的花的组成部分：花朵中的组成部分，如花瓣、萼片和雄蕊成五个一组排列的，如在天竺葵中 【引伸】 pentam.erism n.（名词）
