【正文】
葉植物) A cross section through a mature zone of root tip. A plete transverse section of Ranunculus sp. root at a level showing the pletion of primary growth. Note the lack of pith, accumulation of starch in cortical cells, and the absence of starch in the rhizodermis and exodermis. 毛茛根的初生結(jié)構(gòu) 注意無髓,在皮層細(xì)胞有淀粉積累,但 在表皮和外皮層缺乏淀粉。 Root epidermis and characters 根的表皮及其特征 垂直 Root cortex and characters 根的皮層及其特征 The Casparian strip (凱氏帶) and Casparian dots (凱氏點(diǎn)) in the endodermis (內(nèi)皮層) 起到橫向運(yùn)輸?shù)闹鲃?dòng)控制作用。 凱氏帶 Casparian dots(凱氏點(diǎn)) 內(nèi)皮層 細(xì)胞質(zhì) Cotton root shows Casparian strip (凱氏帶) Two endodermis cells show the cell wall with phellem. 內(nèi)皮層細(xì)胞壁栓質(zhì)加厚, 不透水、氣。 Casparian strip (凱氏帶) of the endodermal cells on radial wall (徑向壁) Vascular cylinder 維管柱(中柱) the primary xylem (初生木質(zhì)部) (stained red), as well as the primary phloem (初生韌皮部, stained green) followed a centripetal, exarch order of differentiation (分化是外始式) . The vascular cambium is located between the xylem and the phloem. (維管形成層位于木韌之間。) a fully differentiated vascular cylinder. Pericycle 中柱鞘 Endodermis 內(nèi)皮層 primary xylem 初生木質(zhì)部 primary phloem 初生韌皮部 vascular cambium initiation 維管形成層初期 Monocots (單子葉植物) A cross section through a mature monocot root 髓 內(nèi)皮層 維管組織 表皮 皮層 ( Smilax, 菝葜 ) Pericycle 中柱鞘 Endodermis 內(nèi)皮層 primary xylem 初生木質(zhì)部 primary phloem 初生韌皮部 Epidermis 表皮 Cortex 皮層 Wheat root 小麥根結(jié)構(gòu)