Root tip were short and thin,the growing point were only made up of few organized cells, cells of root cap were large but few.

• 叶脉维管组织发育不良,导管分子数目少,木质化程度低,根尖短而细,生长点仅由少数具分生能力的细胞组成,根冠细胞大,但数量少。