Surrounding the central cylinder is the pericycle . 围绕中柱的是中柱鞘。
2.
Lateral root any root that arises from the pericycle of another root 侧根：起源于根的中柱鞘的根。
3.
Haplostele a type of protostele having a solid strand of stele with the xylem on the inside encircled by phloem , pericycle , and endodermis 单中柱：原生中柱的一种类型，是由韧皮部、中柱鞘和内皮层包围着内方的木质部构成的实心中柱。
4.
We have observed the following characteristics of anatomical structure and development : ( 1 ) the primary roots belong to archetype and the lateral roots occur in the position toward the xylem of the vascular cylinder ; ( 2 ) the root endodermis consists of thicken casparian strips , and there are from two lo four layers parenchyma cells near the pericycle ; ( 3 ) the pith and resins canals are absent in the toots ; ( 4 ) secondary structure occurs in the root hair zone , and vascular cambium is formed from the parenchyma cells between the primary xylem and primary phloem ; ( 5 ) tanning materials are abundant in pericycle cells and phelloderm cells ; ( 6 ) sclereids are found in secondary phloem , and rays are rather rich in secondary xylem 结果表明：气生不定根具有以下结构特征和发育特点： ( 1 )根为二原型，侧根正对着木质部发生； ( 2 )幼根内皮层细胞具凯氏带加厚，维管柱内紧挨中柱鞘内侧具有2 ~ 4层大型薄壁细胞； ( 2 )根中无髓和树脂道； ( 4 )次生结构发生于根毛区，维管形成层由初生木质部和初生韧皮部之间的薄壁细胞转化形成； ( 5 )中柱鞘和栓内层细胞富含单宁类物质； ( 6 )次生韧皮部有石细胞，次生木质部射线发达。
