1. No category

Chapter Three Leaves

Focus: physiological function, composition,
lobed ,types and inner structure

Difficulty: modification of leaf, difference of
rachis and shoot
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
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1.Photosynthesis
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2.Respiration
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3.Transpiration
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4.Spit water function
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5.Absorption
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6.Preserving function
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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 Mori
Folium Eriobotryae
Folium Artemisiae Argyi
Folium Isatidis
Part Two
一、Composition and Morphology of Leaves
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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
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
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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
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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
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of the blade :
lobed
parted
divided
Veins:
 reticulate
veins
 parallel
veins

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Texture of leaf blades
Membranaceous leaf
Coriaceous leaf
herbaceous 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.
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4
Phyllotaxy :
alternate
opposite
whorled
fascioled
Part Four Modification of Leaves
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1.Bract
2.Scale leaf
3.Acicular leaf
4.Leaf tendril
5.Rhizomorphoid leaf
6.Insect-catching leaf
1.Bract
Bougainvillea spectabilis
Houttuynia cordata
1.Bract(spathe)
Alocasia macrorrhizos
Pinellia ternata
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
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一、Structure of the blade of the Dicotyledon
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⑴Epidermis
⑵Mesophyll
Palisade tissue
Spongy tissue
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⑶veins
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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
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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.
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 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
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Lower-phloem
 The interior side of upper and lower
epidermises has collenchyma and vascular
bundle.
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1
6
3
2
4
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:
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bulliform cell and vascular bundle sheath.
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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
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hypodermis , shrring(chloroplast ditribute
along shirring and enlarge area of
photosynthesis) , plunging stoma , resinic
way.
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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
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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?