Leaf gap ( lacuna ) a region of parenchyma differentiated in the stem vascular cylinder immediately above a diverging leaf trace . lateral connections insure no break in the vascular system 叶隙:叶迹从中柱分出的上方,初生维管柱上方出现的一些薄壁组织细胞,与茎的维管柱结构不同,它的侧向连接保证了茎叶维管系统的连续。