Datta P C, Dasgupta A
Acta Biol Acad Sci Hung. 1977;28(1):97-110.
Many characters of leaf (hair, hypodermal cells, palisade layers, intercellular space, distinction between spongy and palisade parenchyma, "palisade ratio", distribution of collenchyma and sclerenchyma, presence or absence of starch grains, calcium oxalate crystals, number, shape and arrangement of bundles of petiole) are useful distinguishing characters. Reduction of palisade layers seems to be the trend of evolution in Piper and Peperomia.
叶片的许多特征（毛被、皮下细胞、栅栏组织层、细胞间隙、海绵组织和栅栏组织薄壁细胞的区分、“栅栏组织比率”、厚角组织和厚壁组织的分布、淀粉粒的有无、草酸钙晶体、叶柄维管束的数量、形状和排列）都是有用的鉴别特征。栅栏组织层的减少似乎是胡椒属和草胡椒属植物的进化趋势。
