The outer surface of mature sclereids was smooth in Nymphoides, but with many prismatic calcium oxalate crystals in Nuphar.However, the early morphogenesis of these two kinds of sclereids was similar.

• 小莕菜成熟厚壁细胞的外表平滑，但台湾萍蓬草成熟厚壁细胞的外表则可观察到许多多面体的草酸钙晶体，然而小莕菜与台湾萍蓬草叶部厚壁细胞早期的形态发生类似。