It has a well developed root cap with no root hairs developed from its epidermal cells. Stelar structure is tetrarch with pri- mary xylem elements in exarch development. Xylem and phloem strands are arranged in alternate.

• 漂浮根发生于茎节的中柱鞘细胞,它有发育良好的根冠,表皮细胞不分化为根毛,中柱初生木质部为四原型,发育方式为外始式,维管束中的木质和韧皮两部分相间排列,整个器官属内起源,可以说明这一漂浮器官是根而非叶。