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Section Two Stems Definition: important vegetative organ.
Physiological function conduction
supporting function
preservation
breeding
Medicinal value
Herba Ephedrae Cortex Eucommiae
Medulla Tetrapanacis Lignum Aquilariae Resinatum
一、Morphological Features and types
of Stem
1. morphological features☆ Definition: node , internode ,
shoot
☆ buds In fact it is meristem or immature structure of developing organs.
According to the growth location of buds
Normal bud : terminal bud,axillary bud,accesory bud
Adventitious bud
According to the nature of the development of buds
Leaf bud
Flower bud
Mixed bud
According to the activity of buds
Active bud
Dormant bud
Way branching stems
1.Monopodial branching
2.Sympodial branching
3.Dichotomous branching
4.False dichotomous branching
☆2.Stem types woody stem: tree, shrub, subshrub, woody vine
herbaceous stem: annual herb, biennial herb, perennial herb, herbaceous vine succulent stem
☆ 3.Stem Modifications
①upper terraneous stem Leafy stem
Shoot thorn
Hook-like stem
Stem tendril
Tubercle,bulblet
False bulb
Abnormal
aerial stem
1.Leafy shoot
2.leafy stem
3.hook-like stem
4.Shoot thorn
5.stem tendril
6.Tubercle
7.bulblet
Anomalous aerial stem1.Leafy shoot (天门冬) 2. leafy stem (仙人掌) 3. hook-like stem (钩藤)
4.Shoot thorn (皂荚) 5. stem tendril (葡萄) 6. tubercle (示珠芽)
abnormal subterraneous stem
Ⅰ.rhizome .rhizome .tuber .corm Ⅱ Ⅲ Ⅳ
Ⅴ.bulb 1.scaly leaf 2.terminal bud 3.bulb plate 4.adventitious root
Ⅵ. bulb
The abnormal subterraneous stem1.rhizome (姜) 2. tuber (半夏) 3. corm (荸荠)4.bulb (洋葱) 5.lognitudinal onion 6.bulb (百合)
②Primary Structure of Dicot Stems
epidermis ( trichome and stoma ) cortex vascular cylinder
Definition : endarch: The order of differentiation and maturation of primary xyle
m of stem is from the inside to outside, and is known as endarch.
Primary structure of Dicot st
ems
1、 epidermis
2、 cortex
3、 vascular cylinder
4、 collenchyma
5、 parenchyma
6、 phloem fiber
7、 primary phloem
8、 fascicular cambium
9、 primary xylem
10、 pith rays
11、 pith
Transverse section of sunflower
1 、 epidermis
2 、 collenchyma
3 、 resin canal
4 、 cortex
5 、 phloem fiber
6 、 pith rays
7 、 primary phloem
8 、 sieve tube
9 、 fascicular cambium
10 、 vessel
11 、 xylem fiber
12 、 xylem parenchyma
13 、 pith
③Secondary Structure of Dicot StemsA. Woody Dicot Stems
Fascicular cambium , Interfascicular cambium ,
secondary xylem , secondary phloem
Definition :annual ring , early wood , late wood ,
sap wood , heart wood , rhytidome
1.Epidermis
2.Periderm
①phellem phellogen②phelloderm③
3.Cortex
4.Phloem fibre
5.Vascular bundle
①phloem cambium②
③xylem
6.pith
Ⅰ.transverse section Ⅱ.radial section
Ⅲ.tangential section4.Secondary xylem
5.ray6.Annual ring7.Sap wood
8.Heart wood
B. Herbaceous Dicot Stems
The model sketch of herbaceous stem
1.non-glandular hair
2.Glandular scale
3.Collenchyma
4.Epidermis
5. glandular hair
6.Endodermis
7.Fibre
8.Phloem
9.stone cell
10.xylem
c. Rhizome of Dicot Stems
一、 Normal Structure of RhizomaTransverse section of huanglian rhizom
a
1 、 phellem
2 、 cortex
3 、 stone cell group
4 、 5 、 rays
6 、 phloem
7 、 xylem
8 、 pith
Transverse section of the rhizome
of Huanglian
1.cork
2.cortex
3.Stone cells
4.Pericyclic fibre bundles
5.cambium
6.phloem
7.Pith ray
8.xylem
9.pith
二、 Anomalous Structure of Rhizome of Dicot Stems
( 1 ) Anomalous structure of rhubarb rhizoma
Up, 1、 phloem
2、 cambium
3、 xylem rays
4、 star dots
Down, 1、 vessel
2、 cambium
3、 phloem
4、 grume cavity
5、 rays
④Structure of Monocot Stems
①Without cambium and phellogen
②Closed collateral vascular bundle or amphivasal b
undle
③No pith endodermis
⑤Gymnosperm Stems
Like Woody Dicot Stems , but different parts is that
it has tracheid ,rays , xylem parenchyma without x
ylem fiber. Meanwhile secondary phloem is simple.
Transverse Section of Gymnosperm
1、 epidermis 2、 phellem
3、 phellogen
4、 cortex basic meristem
5、 epithelia 6、 phloem
7、 cambium 8、 xylem rays
9、 resin canal
10、 secondary xylem
11、 pith rays
12、metaxylem
13、 protoxylem
14、 pith
Review Questions一 .Definition node , internode , exarch , endarch , annual
ring , early wood , late wood , sap wood , heart wood
二 .simple answer 1.what is the difference of the stem of Mono
cotyledoneae and Dicotyledoneae? 2.what is the function of the stem? 3.How about the secondary structure of the
woody stem?