【正文】
Parenchyma predominates in vascular tissues. 在胡蘿卜根,薄壁細(xì)胞在維管組織中占主導(dǎo)地位,次生韌皮部比次生木質(zhì)部更發(fā)達(dá) the lack of hard mechanical tissues. 缺乏較硬的機(jī)械組織 1 = secondary phloem, 2 = vascular cambium, 3 = parenchymatous “wood (薄壁細(xì)胞的‘木材’) Storage root of a sugar beet (Beta vulgaris), showing the teriary structure 甜菜的儲(chǔ)藏根示三生構(gòu)造 Secondary structure teriary structure 三生構(gòu)造 Storage root of sweet potato (Ipomoea batatas) 地瓜的儲(chǔ)藏根 With a lot of storage paranchyma cells. 具有大量的儲(chǔ)藏薄壁細(xì)胞 4) Lateral root 側(cè)根的形成 Lateral root Primordia 側(cè)根原基 Origin: Pericyclen cells (中柱鞘細(xì)胞)它的起源方式為 endogenous origin(內(nèi)起源)。 。 Formation position of lateral roots is relation to numbers of primary xylem 側(cè)根形成的位置與初生木質(zhì)部的數(shù)目有關(guān) Methods of researching on the roots 5) Root nudule and mycorrhiza 根瘤與菌根 植物根系與土壤中的微生物有密切的關(guān)系,根部分泌的物質(zhì),許多是微生物的營(yíng)養(yǎng)來源,而土壤微生物分泌的一些物質(zhì),又可直接或間接影響根的生長(zhǎng)發(fā)育。高等植物根與土壤微生物發(fā)生的共生現(xiàn)象,通常有 : root nodule and mycorrhiza Glycine max 大豆的根瘤 Vigna unguiculata 豇豆的根瘤 根瘤細(xì)菌 Function of root nodule: increasing absorbility of plant (uptake of minerals). 根瘤的作用,增加植物的吸收 (礦質(zhì)吸收 ) Structure of root nodule 根瘤的結(jié)構(gòu) mycorrhizae 菌根 The roots of most species of seed plants (at least 80%) have asymbiotic relationship with soil fungi in which both anisms benefit. The association are known as mycorrhizae. 許多高等植物的根 (80%)能與土壤中的某些真菌發(fā)生 共生關(guān)系。 無嚴(yán)格的專一性, 比根瘤更普遍 。 在樺樹中的外生菌根 2 is a representation of endomycorriza in Deschampsia cespitosa. 在發(fā)草中的內(nèi)生菌根 . (禾本科 ) A model of two types of mycorrhizae ( 1) Ectomycorrhizae(外生菌根) envelop root tips to establish a symbiotic relatio