1、Section 4 Morphology, structure and development of leaves 第四節 葉的形態、結構及生長發育 Leaves, the lateral organs of a shoot, typically have a more-or-less flattened form, and a dorsiventral （背腹面）structure. The upper (or adaxial，近軸） and lower (abaxial，遠軸) sides of the leaf with respect to the stem are easily di

2、stinguished. In most plants, leaves are dorsiventral in their internal structure. Morphology of leaves1. 葉的形態 Leaves of Dicots, 雙子葉植物的葉1.1 Complete leaf 完全葉Complete leaf composed of petiole, blade and stipule. 完全葉由葉柄、葉片和托葉組成。1、葉片：葉的頂端，扁平，綠色，光合作用。2、葉柄：連接莖與葉片的結構，是莖葉間物質運輸的通道，能調節葉片的位置與方向。3、 托葉：葉柄基部的一對附屬

3、物，形狀多樣，有綠色片狀（光合）、刺狀（保護）、鞘狀裹莖（保護腋芽）。1.2 plete leaf 不完全葉Lack of any one or two parts of petiole, blade and stipule. 缺乏葉柄、葉片和托葉中的任何一部分或二部分No petiole andstipuleNo stipule1.3 Leaf of Paoceae, Monocots. 單子葉禾本科植物的葉.Blade 葉片Leaf sheath葉鞘Leaf ligulate葉舌Leaf auricle葉耳1.4 Simple leaf and compound leaves 單葉與復葉S

4、imple leaf: one blade and one petiole;Compound leaf: over two blades (leaflet) and over two petiolules 單葉：一個葉片，一個葉柄；復葉：2個以上葉片（小葉片）和2個以上 小葉柄 1.4 Simple leaf and compound leaves 單葉與復葉Populus sp. 楊樹Pisum 豌豆 Compound leaves 復葉pannately compound leaves羽狀復葉palmately compound leaves 掌狀復葉基本類型復葉類型：掌狀復葉；羽狀復葉；

5、三出復葉；單身復葉1.5 Leaf venation 1） Reticulate venation - Characteristic of dicots 網狀脈- 雙子葉的特征The minor veins join with other minor veins, forming a conspicuous network. The reticulate pattern of minor veins is characteristic of most dicotyledonous plants.細脈和其它的細脈聯合形成一個連續的網絡。細脈的網狀式樣是雙子葉植物的主要特征。2） Parallel

6、 venation - Characteristic of monocots 平行脈 - 單子葉植物的特征The detail from corn (Zea mays) leaf shows parallel venation of the major veins. Careful observation of such leaf lamina shows that veins do branch and converge in places, especially near the base and apex of the blade. 玉米葉的細節表明主脈的平行排列模式。仔細的觀察表明葉脈

7、在某些地方分支和聯合，尤其在葉片的頂端和基部。3） Dichotomous venation - Characteristic of primitive plants, e.g. Ginkgo 二叉分支脈 - 原始的特征，銀杏Ginkgo is a primitive gymnosperm that is now widely cultivated. The leaves are distinctive due to the open dichotomous branching of the veins.2. Development of leaf 葉的發育Leaf primordium is

8、 of exogenous origin, which from the First and second layer of cells in Dicots, and from the first layer of cells in Monocots.葉原基是外起源的，在雙子葉植物來自第1-2層細胞，而單子葉植物來自第1層細胞。2.1 origin of leaf 葉的起源 2.2 Growth of leaf 葉的生長1.葉原基; 2-3.頂端生長成葉軸; 4.邊緣生長; 5.居間生長成成熟葉 Leaf promodium - apical growth - marginal growth

9、- intercalary griwth - mature leaf.3. Structure of mature leaves 成熟葉的結構3.1 structure of petiole 葉柄的結構The structure is similar to primary structure of stem.葉柄的結構與莖的初生結構相似。The stem has 11 bundles, 3 of which produce leaf Traces that enter the petiole. 3.2 structure of leaf blade in dicots 雙子葉植物葉片結構 Bl

10、ade structure is composed of upper and lower epidermis, mesophyll and vein.從經過中脈的橫切面中，可以見到上下表皮，葉肉和葉脈三部分組成1） Upper and lower epidermis 上下表皮The epidermis is mostly a layer of cells, which is mainlycomposed of epidermis cells, stomatal apparatus and trichomes. 葉表皮多為一層細胞，由表皮細胞, 氣孔器和毛狀體組成。 1 = adaxial ep

11、idermis, 2 = palisade mesophyll, 3 = spongy mesophyll, 4 = intercellular space, 5 = xylem of minor vein 6 = phloem of minor vein, 7 = bundle sheath, 8 = bundle sheath extension, 9 = abaxial epidermis, 10 = stoma Stomatal apparatus 氣孔器毛狀體Stomatal apparatus are often distributed in lower epidermis. Ep

12、idermis cells is of different shape indifferent plants. 氣孔器常分布下表皮, 在不同植物中表皮細胞有不同的形狀。氣孔器Stomatal apparatus 氣孔器A stomatal crypt of Nerium olender under SEM. 掃描電鏡下的夾竹桃氣孔穴Lower epidermis in Elytrostrachys (Paoceae) 禾本科Upper multiple epidermis with cuticle in Nerium olender夾竹桃葉的上表皮是復合的, 具有外被層維管束鞘Trichome

13、s on leaf epidermis 在葉表皮上的毛狀體 Hydathode 排水器Fragaria 草莓Strawberry leaves with drops of guttation water at vein endings along the edges. 草莓在葉緣具有吐水現象Guttation is caused by root pressure2） Mesophyll 葉肉Dorsiventral (bifacial) leaf (兩面葉) ： mesophyll can be diveded into palisade tissues and spongy tissues.

14、 葉肉可以分為柵欄組織和海綿組織葉肉柵欄組織海綿組織Ligustrum 女貞葉片橫切Dorsiventral (bifacial) leaf (兩面葉) ： Mesophyll under SEM. 掃描電鏡下的葉肉PalisadeParenchyma（2 layers ofCells)Spongy paranchymaLeaf structure of lilac, Syringa vulgaris丁香葉的結構 Unifacial leaves, 等面葉 3） veins 葉脈From main vein - the secondary main vein - the third later

15、al vein - minor vein - vein ending to mesophyll cells從主脈 - 2級主脈 - 3級側脈 - 細脈 - 脈梢 - 葉肉細胞Minor veins show all mesophyll cells are close to one vein or another. 細脈表明所有葉肉細胞總是與某一個葉脈接近。In a large lateral vein大側脈的縱切面 穿孔Structure of main vein 主脈的結構主脈是葉柄的延伸，結構近葉柄。從上往下為上表皮、機械組織、木質部、微弱形成層、韌皮部、薄壁細胞、機械組織、下表皮Syri

16、nga 丁香厚角細胞微弱形成層Structure of the secondary main vein 次級主脈的結構The structure is similar to major vein, but cells of each part decrease in correspondence and different plants have differentiation. 結構基本相似，但各部分結構相應減少，各種植物有分化。Structure of the third lateral vein 三級側脈的結構各部分相應減少，但有維管束鞘的結構。石細胞Water lily, (Nymph

17、aea ordorata)睡蓮Structure of minor vein 細脈的結構往往只有1-2個導管和1-2個篩管3.3 Structure of leaf blade in Monocots 單子葉植物葉片結構(以禾本科植物為例) Blade structure is also composed of upper and lower epidermis, mesophyll and vein.結構組成：表皮、葉肉、葉脈。Homogenous mesophyll, large intercellular spaces, moderate sclerenchyma.相同的葉肉細胞，較大的

18、細胞間隙，適度的厚壁細胞1） Upper and lower epidermis 上下表皮1.栓細胞; 2.硅細胞; 3.刺毛; 與雙子葉植物不同，有長短細胞之分，并有特殊的泡狀細胞（bulliform cell); 短細胞又分硅細胞和栓細胞。氣孔器保衛細胞呈啞鈴型，兩面均有分布。5.長細胞6. 氣孔器4.泡狀細胞; 水稻，Oryza sativa 水稻氣孔器的結構 A.表面觀; B.氣孔中央橫切; C.氣孔頂端橫切 1.保衛細胞; 2.副衛細胞; 3.氣孔Stomatal apparatus 氣孔器中脈氣孔泡狀細胞葉肉細胞機械組織Pao annual 早熟禾C3 Plant2） Mesoph

19、ylla 葉肉屬于等面葉，細胞在有些種中較為特殊單子葉植物平行脈縱面觀維管束鞘薄壁細胞葉肉細胞維管組織3） Vein and C3 & C4 Plants 葉脈及碳3、碳4植物平行脈，有限維管束，但有特殊的維管束鞘Typical leaf of a C3 grassNo palisade mesophyll; small bundle sheath cells with a few chloroplasts.典型碳3植物，無柵欄組織，維管束鞘細胞小，含葉綠體少3 = bundle sheath, 7 = minor vein, 10 = non-glandular hairs, 11 = st

20、oma Brome-Grass， 雀麥草的中脈Vein and C3 & C4 Plants 葉脈及碳3、碳4植物Lateral vein of Triticums C3 Plant小麥(碳3植物）葉的側脈With two layers of Bundle Sheath.有2層維管束鞘，葉綠體少而小。C4 plants - Kranz Anatomy 碳4植物的花環結構Bundle sheath cells are large. Rich in chloroplasts & other organelles. 維管束鞘大，富含葉綠體和其它細胞器。Leaf section of amaranth

21、 (Amaranthus retroflexus), a C4 plant exhibiting Kranz (wreath) anatomy.一種莧科植物，具有C4植物的花環特征Grass leaf with Kranz anatomy - C4 plant 有花環結構的禾草Two bundle sheathsOuter one is parenchymatous; inner is a mestome sheath2層維管束鞘，外層薄壁的，內層厚壁鞘狀的。Grama-grass (Bouteloua breviseta)垂穗草 Sugar cane， C4 plant - Single b

22、undle sheath 甘蔗, 碳4植物 -單層維管束鞘Sugar cane (Saccharum officinarum), a C4 plant. The bundle sheath cells (wreath) are smaller and more numerous. Bundle sheaths consist of one layer of parenchyma cells. 碳4植物，具一層花環型維管束鞘細胞3.4 Unifacial leaf of a non-grassy monocot: Iris 非禾草單子葉植物的等面葉結構：鳶尾屬Has similar tissue

23、 organization at both surfaceswith a row of vascular bundles under each epidermis. 葉兩面組織相同，有一排維管束在表皮下，很特殊。1 = an epidermal papilla, 表皮乳突2 = sclerenchyma, 厚壁3 = phloem, 4 = xylem, 5 = lysigenous slime cavity, 熔生的粘液腔6 = homogeneous mesophyll 同形的葉肉3.4 leaf of a non-grassy monocot: Palm 非禾草單子葉植物葉的結構：棕櫚屬

24、Cross-section of a petiole of the palm stained to show its numerous vascular bundles. This leaf is very large and must have a massive conduction system.3.4 leaf of a non-grassy monocot: Yucca 非禾草單子葉植物葉的結構：絲蘭屬3.4 leaf of a non-grassy monocot: Yucca 非禾草單子葉植物葉的結構：絲蘭屬3.4 leaf of a non-grassy monocot: Dr

25、acaena 非禾草單子葉植物葉的結構：龍血樹屬4. Ecological type of leaves 葉的生態類型4.1 Sun & Shade Leaves 陽生葉與陰生葉Shade leaves are thinner than sun leaves. Have poorly developed palisade mesophyll. Light intensity is an important ecological factor affecting leaf anatomy. .One is taken from a shade leaf which is thin and has

26、 a many spongy mesophyllThe another leaf under sun shows a much more developed palisade mesophyll陰生的陽生的陰生的begonia (Begonia sp.)秋海棠4.2 Xeromorphic Angiosperm Leaves 旱生植物葉Typical xeromorphic leaf of a grass forms the tough leaves with a high proportion of sclerenchyma.beach grass (Ammophila arenaria).

27、喜沙草屬下陷的穴Xeromorphic leaves of a non-grassy monocot非禾本科植物旱生葉With massive columns of fibers, Lysigenous central air cavities in New Zealand hemp (Phormium tenax) leaf.在新西蘭麻葉中，可見大量柱狀的纖維，和熔生的氣室。 very thick cutin厚的角質層 Modified cells for water-storage變態的細胞，用于儲藏水分。 旱生的羊棲菜屬植物 （藜科） saltwort. saltbush (Atripl

28、ex sp.) leaf, a xerophytic plant. 旱生植物濱藜Xeromorphic Gymnosperm Leaves 裸子植物旱生葉Compact homogeneous mesophyll. Two vascular bundles enclosed in transfusion tissue (輸導組織）.Resin ducts (樹脂道）emerged in mesophyllvery thick cutin厚的角質層 (Pinus sylvestris) 松樹4.3 Hydromorphic Leaves & Water Storage （水生葉） 水生植物的葉以

29、及儲氣的結構A leaf from the submerged hydrophyte（沉水植物）, water milfoil (Myriophyllum sp.). The plant has finely pinnately divided leaves （羽狀分裂）which lack cuticle, stomata, sclerenchyma in the mesophyll.缺外被層，氣孔，厚壁細胞ater milfoil (Myriophyllum sp.).一種耆草 Bifacial floating leaf in Potamogeton眼子菜屬的兩面浮水葉Stomata a

30、re on upper surface. Air spaces in spongy mesophyll provide buoyancy . 氣孔在上表面氣室提供浮力Unifacial submerged leaf in Potamogeton眼子菜屬的單面沉水葉No stomata presentMesophyll one-layeredross-sectioned leaf of tape grass (Vallisneria sp.), a submerged monocot. 沉水的帶草Modified leaves - adaption to environment Modified

31、 leaves - adaption to environment Senecio rotundifolia園葉千里光Dinteranthus石頭植物Lithops, stone plant 石頭植物5. Abscission of leaves and deciduous tree 葉的離層和落葉樹秋天：離區出現，離層形成。離層溶解，葉脫落，斷裂處細胞栓化，保護層形成。6. Function of Leaves葉的功能：A. 光合作用B. 蒸騰作用C. 吸收、繁殖Section 5: Relationships among the vegetative organs第五節:營養器官之間的聯系1. Links of vascular tissues among roots, stems and leaves 根、莖、葉之間維管組織的聯系Stem and leaf2. Relativity of vegetative organs 營養器官生長的相關性 - 植物體各個器官，在生長的過程中存在著相互促進或抑制的關系，稱為生長相關性。2.1 Relativity between parts under ground and parts Above 植株地下部分與地上部分的生長相關性 -根冠比2. 2 Relativity of top bud