根 器官（organ）：植物体中由多种组织组成的，具有显著形态特征和特定生理功能的部分 营养器官（vegetative organ）：在植物生活史中，在营养生长期担负着有关植物生理活动功能的器官，如根、茎、叶 根 植物体用于固着和吸收水分及无机盐的器官，通常位于地下 The water- and mineral-absorbing part of a plant which is usually underground, does not bear leaves, tends to grow downwards and is typically derived from the radicle of the embryo. A single mature ryegrass plant 15million individual roots and branch roots with a combined length of 644 kilometers Total surface area larger than a volleyball court All contained within 0.57 cubic meter 14 billion root hairs with a total surface area almost the size of a football field.note When a seedling or plant is moved, many of the delicate root hairs are torn off or die within seconds if exposed to the sun, thereby greatly reducing the plants capacity to absorb water and minerals in solution. This is why plants should be watered and shaded and pruned after transplanting until new root hairs have formed.根的功能 吸收、输导、贮藏 固着、支持 合成、分泌，其分泌的粘液等可以减少根与土壤间的摩擦力和促进根对土壤中物质的吸收。
其它、固氮，大豆肥田 storageAbsorption water and mineralsArchnorage of plant soilConduction of water and solution根:植物体用于固着和吸收水分及无机盐的器官，通常位于地下玉米根叶甲 Diabrotica virgifera吸引天敌象甲好吃的杀无赦!大哥，快来昆虫病原线虫玉米根系研究方法微探管原位照相地下观测-海洋馆核磁共振根系类型 直根系：主根粗壮发达，主根与侧根区分明显的根系 须根系：主根不发达，由茎的基部产生许多不定根的形成的须状根系 主根和侧根：主根由胚根发育而来主根向地生长的同时，不断地产生侧根及再在侧根上产生二、三等级支根，主根和侧根称为不定根 不定根由茎叶、老根和胚轴上形成的根，由于根产生的位置不固定，称不定根 定根：主根和侧根等产生位置固定，称固定根根的形态 Most Dicotyledonous （双子叶）plants(e.g. peas and carrots whose seeds have two “seed leaves” commonly referred to as dicots) have taproot systems with one or occasionally more, primary roots from which the secondary roots develop and secondary . Monocotyledonous （单子叶） plants (e.g. corn and rice whose seeds have one “seed leaf”-commonly referred to as monocots), on the other hand, have fibrous root systems.根尖 从根的顶端到着生根毛的部位，是根中生命活动最活跃的部分。
自下而上依次包括根冠、分生区、伸长区、成熟区root cap The The Thezone of maturationzone of elongationzone of cell division根冠： 根尖顶端的圆锥状结构，由许多排列不规则的薄壁细胞组成 根冠由3种不同类型的细胞组成 根冠分生细胞，又称根冠原，与分生相连根冠中央细胞，又称根冠柱，有感受重力的作用根冠外部细胞，能分泌粘液，随着根生长不断脱落，寿命约4-9天 根冠分生细胞不断分裂，产生新细胞，根冠中央细胞逐渐外移，补充不断死亡的细胞，使根冠细胞数目恒定根冠的功能 保护作用 先锋作用 平衡石作用重力静止中心： 在根顶端分生组织的中心区域，细胞分裂的频率低或不分裂，大约比周缘细胞分裂慢10多倍这个惰性区域称静止中心其作用可能是根尖合成激素或是储备分生组织的场所 The other region of cell division divided every 12 or 36 hours, while at the base the meristem, they may divided only once every 200 to 500 h.分生区： 分生区：meristematic zone由顶端分生组织构成，也称生长点，长13mm，分生区顶端的原始分生细胞不断分裂，稍后就分化为原表皮，基本分生组织和原形成层等初生分生组织，由于原始分生细胞的存在，分生区始终保持着分裂能力和原有的体积。
Cells in this region are mostly cubical, with relatively large, more or less centrally located nuclei and a few very small vacuoles. Protoderm: gives rise to an outer layer of cells, the epidermis Ground meristem: to the inside the protoderm, produces parenchyma cells of the cortex. Procambium: which appears as solid cylinder in the center of the root, produces primary xlyem and primary pholem. Pith tissue: which originates from the ground meristem, is generally present in stems but absent in most dicot roots. Grass roots and those of most other monocots, have pith tissue.伸长区 长约210nm，位于分生区之后，该区域细胞已逐渐停止分裂，并明显地沿根的长轴方向延伸。
伸长区细胞在延长的同时，已开始细胞分化，未成熟的木质部导管和未成熟的韧皮部筛管往往出现在该区域细胞长宽比逐渐增加成熟区 伸长区后具根毛的部分，又称根毛区该区细胞已停止伸长，并且已分化成熟，形成各种组织Region of maturation Most of the cells mature, of differentiate, into the various distinctive cell types of the primary tissues in this region, which is sometimes called the region of differentiation, or root hair zone. 根的成熟区内由初生分生组织分化为各种成熟的初生组织，组成了根的初生结构，由外至内明显地分化为表皮、皮层和维管柱等三部分双子叶的植物根的初生结构。