叶组织由植物细胞层组成。不同的植物细胞类型形成叶中发现的三种主要组织。这些组织包括夹在两层表皮之间的叶肉组织层。叶脉管组织位于叶肉层内。外叶层称为表皮。表皮分泌一种称为角质层的蜡状涂层，有助于植物保持水分。植物叶子中的表皮还含有称为保卫细胞的特殊细胞，其调节植物与环境之间的气体交换。保卫细胞控制表皮中称为气孔（奇异气孔）的毛孔的大小。打开和关闭气孔允许植物根据需要释放或保留包括水蒸气，氧气和二氧化碳的气体。中叶肉叶层由栅栏叶肉区和海绵状叶肉区组成。 Palisade叶肉包含柱状细胞，细胞之间有空隙。大多数植物叶绿体存在于栅栏叶肉中。叶绿体是含有叶绿素的细胞器，叶绿素是一种绿色色素，可以吸收阳光中的能量进行光合作用。海绵状叶肉位于栅栏叶肉下方，由不规则形状的细胞组成。在海绵状叶肉中发现叶状维管组织。
英国北约克郡Essay代写：二氧化碳
Leaf tissue consists of a layer of plant cells. Different plant cell types form the three major tissues found in the leaves. These tissues include a layer of mesophyll tissue sandwiched between two layers of the epidermis. The leaf vascular tissue is located in the mesophyll layer. The outer leaf layer is called the epidermis. The epidermis secretes a waxy coating called the stratum corneum that helps plants retain moisture. The epidermis in plant leaves also contains special cells called guard cells that regulate the gas exchange between the plant and the environment. The guard cells control the size of the pores in the epidermis called stomata (singular stomata). Opening and closing the vents allows the plant to release or retain gases including water vapor, oxygen and carbon dioxide as needed. The middle leaf leaf layer consists of a flocked meat area and a spongy area. Palisade mesophyll contains columnar cells with gaps between the cells. Most plant chloroplasts are found in foliar flesh. Chloroplasts are organelles that contain chlorophyll, a green pigment that absorbs energy from sunlight for photosynthesis. Spongy mesophyll is located below the foliate flesh and consists of irregularly shaped cells. Leafy vascular tissue was found in spongy mesophyll.