Chapter 6 The Leaf,Functions,Photosynthesis Respiration Transpiration Storage,Form,Three parts: Leaf blade Petiole Stipule Complete, Incomplete,Leaf blade Petiole Stipule,Leaf Types,Simple leaf the blade is all in one piece, though it may be lobed, toothed, etc. Compound leaf the blade is divided all the way to the midrib (rachis) into two or more pieces (leaflets). Pinnate, Palmate, Unifoliate,Simple Leaf,Compound Leaf,The Difference between a Stem with Simple Leaves and a Compound Leaf,1. The tip of the rachis never has a terminal bud. 2. Leaflets never bear buds in their axils. 3. Leaflets all lie in the same plane. 4. The rachis falls off with leaflets.,The Leaf Morphology,Leaf shapes Leaf margins Leaf apices Leaf bases Leaf lobes Leaf venation Leaf texture,Leaf shapes,Leaf shapes,Leaf margins,Leaf apices,Leaf bases,Leaf lobes,The Difference between Leaflets and Lobes,Petiolules: exist or not Rachis: exist or not Arrangement: symmetric or not Shapes and Size: similar or not,Leaf venation,The Phyllotaxis,General rule: mosaic arrangement 互生 Spiral (Alternative) 对生 Opposite 轮生 Whorled 簇生 Fascicled,The Modified Leaves,苞片 Bracts 鳞片 Scales 叶刺 Spines (Thorns, Prickles) 叶卷须 Tendrils 叶状柄 Phyllodes 捕虫叶 Insect traps 异型叶性 Heterophylly,苞片 Bracts,苞片 Bracts,鳞片 Scales,鳞片 Scales,叶刺 Spines,叶卷须 Tendrils,叶状柄 Phyllodes,捕虫叶 Insect traps,捕虫叶 Insect traps,叶的内部结构,表皮 Epidermis 叶肉组织 Mesophyll 维管组织 Vascular tissues 两种类型: 两面叶 Bifacial leaves: 水平伸展 等面叶 Isolateral leaves: 垂直伸展,表皮 Epidermis,组成： 扁平、板块状的表皮细胞；保卫细胞；表皮毛 气孔的分布： 两面叶：单侧性分布 等面叶：对称性分布,薰衣草叶 Lavender Leaf,Lavender-leaf,花生叶 Pea Leaf Stoma, Vicea sp. (SEM x3,520).,Cross-Section Through a Stomata,Subsidiary cell,Guard cell,Substamatal chamber,叶肉组织 Mesophyll,两面叶： 栅栏组织 Palisade mesophyll 海绵组织 Spongy mesophyll 等面叶： 同型叶肉组织,维管组织 Vascular Tissues,中脉与侧脉： 维管束鞘 初生韧皮部（下） 初生木质部（上） 小叶脉： 逐渐简化,