Chapter Three Leaves Focus: physiological function, composition, lobed ,types and inner structure Difficulty: modification of leaf, difference of rachis and shoot

Definition ,Physiological Function and Medicinal Value of Leaves Part One Definition ,Physiological Function and Medicinal Value of Leaves ● 一、Definition The leaf is the important vegetative organ of the plant. It is generally green flat body, have phototropism(向光性).

● 二、Physiological function of the leaves 1.Photosynthesis 2.Respiration 3.Transpiration 4.Spit water function 5.Absorption 6.Preserving function 7.Reproductive function

1.Photosynthesis

2.Respiration

3.Transpiration

4.Spit water function

5.Absorption

6.Preserving function Fritillaria verticillata  Willd． var．thunberqii

7.Reproductive function Begonia masoniana Bryophyllum pinnatum

● 三、Medicinal value of the leaves

Folium Artemisiae Argyi Folium Mori Folium Artemisiae Argyi Folium Eriobotryae Folium Isatidis

Part Two 一、Composition and Morphology of Leaves Fig. One composition of leaf 1. blade 2. Petiole 3. stipules 4.ocrea(托叶鞘)

Definition Complete leaf :has three parts called complete leaf. Incomplete leaf :Lack a part or two parts called incomplete leaf.

Composition of Leaves Blade: green , flat Petiole: Join the blade and stem ,and support the blade Stipules: Protect the immature blade

Petiole modification bulgy petiole Leafy petiole Sheath-like petiole Trans-petiole Leafy petiole Sheath-like petiole

Stipules Modification Ⅰ.Cihuai Ⅱ.Qiancao Ⅲ.Yuxingcao Ⅳ.Laliao Ⅴ.Wandou Ⅵ.Qiangwei Ⅶ.Baqia 1.Stipules 2. tendril 3. thorn 4. ocrea

二、 Morphology of Leaves 1.The whole shape of the blade 2.The form of the leaf apex 3.The form of the leaf base 4.The form of the leaf margin

The whole shape of the blade

The form of the leaf apex

The form of the leaf base

The form of the leaf margin

Heterophylly: the same plant have different shaped leaves or the plants have different forms leaves in the defferent stages, this kind of phenomenon called the Heterophylly.

lobed of the blade : lobed parted divided

Veins: reticulate veins parallel veins

Texture of leaf blades herbaceous leaf Membranaceous leaf Coriaceous leaf Succulent leaf

Part Three Types of Leaves Simple Leaf and Compound Leaf Definition simple leaf（单叶）：Only grow a slice of blade on a petiole compound leaf (复叶)：Grow two or more blades on a petiole 1. ternately compound leaf ⒉ palmately compound leaf ⒊ pinnately compound leaf ⒋ unifoliate compound leaf

Types of compound leaf 1.ternately compound leaf 2.ternately compound leaf 3.palmately compound leaf 4. odd-pinnately compound leaf 5.even-pinnately compound leaf 6.bipinnate leaf 7.tripinnate leaf 8.unifoliate compound leaf

The type of compound leaf

※The difference of rachis and shoot ①Terminal bud in shoot，but it isn’t in rachis. ②Bud in common petiole and leaflet base without bud. ③All leaflet of rachis in plane. ④Whole compound leaves fall off or leaflet fall off first , than rachis and common petiole fall off. but shoot not fall off.

4 Phyllotaxy : alternate opposite whorled fascioled

Part Four Modification of Leaves 1.Bract 2.Scale leaf 3.Acicular leaf 4.Leaf tendril 5.Rhizomorphoid leaf 6.Insect-catching leaf

1.Bract Bougainvillea spectabilis Houttuynia cordata

Alocasia macrorrhizos 1.Bract(spathe) Alocasia macrorrhizos Pinellia ternata

Opuntia stricta(Haw.)Haw.var. dillenii 2. Scale leaf 3.Acicular leaf fritillaria Opuntia stricta(Haw.)Haw.var. dillenii

4.Leaf tendril Pisum sativum Linn. Smilax china L.

5.Rhizomorphoid leaf Salvinia natans Ceratophyllum demersum

6.Insect-catching leaf Dionaea muscipula

6.Insect-catching leaf Drosera peltata Smith var. multisepala

6.Insect-catching leaf Nepenthes mirabilis

Part Five Inner structure of the blade 一、Structure of the blade of the Dicotyledon ⑴Epidermis ⑵Mesophyll Palisade tissue Spongy tissue ⑶veins

⑴Epidermis: upper epidermis , lower epidermis , multiple epidermis(2-3layers of cells) ★cutin : control the transpiration of the moisture , strengthen mechanical performance , prevent the germ from invading. ★hair : for distinguish the basis of the folium ★stoma : lower stoma more than upper stoma

⑵Mesophyll Palisade tissue: it is neat to arrange , take the form of bar , having a large number of chloroplasts.

Spongy tissue : like sponge , the cell is irregular and arranging loosely , the interval is relatively big.

Definition Isobilateral leaf： No matter the form or internal structure are all similar in the upper and lower two sides of the leaf, call the Isobilateral leaf . (It is more seen in Gramineae . It can receive the light in the two sides . The mesophyll has no division which palisade tissue and sponge tissue or upper and lower sides have palisade tissue . ) For example , aiye

bifacial leaf：No matter external form or internal structure are all obviously different in the upper and lower two sides of the leaf, call the bifacial leaf or dorsi-ventral leaf . (the color of upper side :dark green , lower side : light green ) this bifacial leaf is common . For example , mint and tea.

⑶veins: upper-xylem Lower-phloem The interior side of upper and lower epidermises has collenchyma and vascular bundle.

3 2 4 1 6 7 8 9 5 Transverse section of leaf of Herba Menthae 1.non-glandular hair 2.upper epidermis 3.palisade tissue 4.spongy tissue 5.lower epidermis 6.stoma 7.Xylem 8.phloem 9.collenchyma

二、Structure of the Blade of the Monocotyledon △Character: bulliform cell and vascular bundle sheath.

1、upper epidermis 2、stoma 3、epidermis hair Structure of the blade of Monocotyledon 1、upper epidermis 2、stoma 3、epidermis hair 4、parenchyma 5、vascular bundle in midrib 6、bulliform cell 7、sclerenchyma 8、lower epidermis 9、cutin 10、 vascular bundle in lateral veins

三、Structure of the Blade of the Gymnosperm hypodermis , shrring(chloroplast ditribute along shirring and enlarge area of photosynthesis) , plunging stoma , resinic way.

Structure of the blade of Gymnosperm 1、lower epidermis 2、mesophyll 3、upper epidermis 4、endodermis 5、cutin 6、vascular bundle 7、stoma 8、resin canal 9、parenchyma 10、the room under stoma

Review Questions 一.Definition Complete leaf , incomplete leaf , heterophylly, simple leaf, compound leaf , unifoliate compound leaf , bifacial leaf and isobilateral leaf 二.simple answer 1.what is the difference of the rachis and small shoot? 2.what is the function of leaves? 3.How about the inner structure of leaves of Dicotyledoneae?