Plant anatomy

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Plant anatomy (植物解剖学)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

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Tissue system (組織系)

a group of tissues that work together to perform specific functions

= (epi)dermal system (表皮系) +

vascular system (維管束系) +

fundamental system (基本組織系)

1868, 1875 Sachs (Plant physiologist): tissue sytem =

divided into dermal, fundamental and vascular systems
1965 Esau supported this classification

1884 van Tieghen: tissue sytem =

divided into epidermis, cortex and central cylynder (or stele)

⇒ Sachs and van Tieghen proposed "tissue system"
1884 Haberlaudt: based on physiological anatomy,

dermal tissue (皮膚組織), mechanical tissue (機械組織), absorptive tissue (吸収組織), assimilatory tissue (同化組織), conductive tissue (通導組織), storage tissue (貯蔵組織), aerenchyma (通気組織), secretory tissue (分泌組織), locomotive tissue (運動組織), sensitive and/or sensory organ (感覚器官), stimulus conducting tissue (刺激伝達組織)

1922 Lundegårdh: based on the aggregation of cells in the tissues→

classfied tissue systems into integrated and dispersed systems
Ex. dispersed systems: stomata, fine roots, idioblast (異形細胞)

[morphology, embryology, seed]

(Epi)dermal system (表皮系)

Fundamental sytem (基本組織系)

Vascular systems (維管束系)

Meristem (分裂組織)

Protomeristem (前分裂組織)

= a cluster of cells at an undifferentiated stage within the meristem

developed protomeristem Ex. protoderm, procambium and ground meristem

Flower (花)

1676 Grew, Nehemiah (1641-1712), plant anatomy

hypothesized the presence of male and female in plants
♂ stamen = reproductive organ → pollen = sperm-like

1694 Camerarius, Rudolf Jakob (1665-1721), botany

Ricinus communis and others: removed stamens before flowering
→ no seeds ⇒ stamen = ♂ (imperfect demonstration)

Process of corolla formation

A) flower arrangement
Magnoliaceae = spiral arrangement → [semi-] → cyclic arrangement = Fabaceae
1: spiral arrangement: primitive unspecialized perianth

Ex. Magnoliaceae, Calycanthaceae, Himanthandraceae, Nymphaeceae
Corolla arrangement - spiral
Stamen, carpel (pistil) - many

2: cyclic arrangement: monocyclic arrangement, dicyclic arrangement, tricyclic arrangement, etc.
3: semi-cyclic arrangement
B) modified stamens
a) Se | P → St
b) Se → P-St

Vascular bundle system (維管束系, VBS)

= (fibro)vascular bundle system = phloem (師部)+ xylem (木部, cell wall only)
Vascular plants, having the conducting tissues, xylem and phloem, have come to dominate terrestrial habitats, so much so, in fact, that they are sometimes spoken of as “the land plants” a designation that quite overlooks may algae, fungi, liverworts and mosses that share this same habitat. Pteridophyta (ferns), seed plants

endodermis

Ex. ferns: inner endodermis = stele, central cylinder

Parenchyma (柔組織): tissue composed of living-walled cells, most often functioning in photosynthesis or storage
xylem

Fig. Elements of the xylem

Fig. Elements of the phloem

Microscopic observation of vascular bandle system

Objectives: understanding the structures of vascular bandles, based on the comparisons between monocotyledons and dicotylenons
Materials (often used for training): Cucurbita moschata var. Toonas (or Cucurbita maxima) = dicotyledonae, and Zea mays = monocotyledonae

Slice thinnly the stems of pumpkins and corns by a razor blade or other sharp blade.
Soak into 50% Et-OH mixed with 1% safranin for 1 hr
Soak into 50% Et-OH for ca 10 sec
Soak into 75% Et-OH for ca 10 sec
Soak into 85% Et-OH for ca 10 sec
Soak into 95% Et-OH for ca 10 sec

Soak into 100% Et-OH for ca 10 sec
Soak into 100% Et-OH mixed with 1% light green for ca 30-120 sec
Soak into 95% Et-OH for ca 10 sec
Soak into 100% Et-OH for ca 10 sec
Soak into 100% Et-OH for ca 10 sec
Soak into the solution made of Et-OH:xylene = 1:1 for ca 10 sec
Soak into 100% xylene for ca 10 sec
Soak into 100% xylene for ca 10 sec
Mount by Canada balsam
Observation under a microscope

Cambium (形成層)

pl. cambia or cambiums
a thin formative layer between the xylem and phloem of most vascular plants that gives rise to new cells and is responsible for secondary growth

Xylem (木部)

Function

transportation of water and nutrients from roots
mechanical support
storage
protection

Vessel (導管)

lost cell wall and made single tube

scalariform

spiral

Tracheid (仮導管)

developed in all vascular plants
a long and tapered lignified cell in the xylem

xylem
lost cell wall and made single tube
pit (壁孔)

Fibrous tissue (繊維組織)

tissue consisting of or containing fibers

Xylem parenchyma (木部柔組織)

Phloem (師部)

→ nutrient transport
a) sieve tube (→ sieve plate: cell wall of phloem forms into a sheet)
b) companion cell
c) phloem fiber
d) phloem parenchyma
e) fibrous tissue
f) resin canal

Pit

Alternate pit
Bordered pit
Half-bordered pit
Simple pit: ramiform pit
Vestured pit

_________bordered pit_____simple________◎: pit

Stele (中心柱)

= central cylinder, vascular cylinder
= vascular or vessel bundle tissue + its related tissues
Morphologically-various steles

seed plants → a few types
ferns → diverse steles used for taxonomical key

Evolutionary relationship

amphipholic siphonostele (両師管状中心柱) → dictyostele (網状中心柱)
ectophloic siphonostele (多師管状中心柱) → eustele (真正中心柱)

A. protosteles (原生中心柱):

are the simplest, and are often considered to be the most primitive, type of stele. Protosteles occur in Psitophyta and Microphyllophyta and in the juvenile stems of other groups (in many roots as well).

A₀: concentric vascular bundle (包囲維管束): fossil records only
A₁: haplostele (単一中心柱)
A'. actinostele (放射中心柱)
= radical vascular bundle (放射維管束)

Ex. Psilotum
Ex. all the vascular plants

sweet potato = root ↔ potato = (underground) stem

A''. plectostele (背腹中心柱)

Ex. Lycopodium

e: endodermis, p: phloem, x: xylem

B. ectophloic siphonostele (solenostele) (外部管状中心柱)

B'. amphipholic siphonostele (両節管状中心柱)
stele

C. dictyostele (網状中心柱)

In siphonostelic stems with short internodes, overlapping of the nodal leaf gaps results in disection of the stele. As seen in transection, the stele appears as discrete strands or bundles, each surrounded by endodermis and the phloem surrounding the xylem. A siphonostele thus disected is called a dicotyostele. This type of stele characterizes many ferns.

D. eustele (真正中心柱)

= collateral vascular bundle
Where the xylem and phloem occur in discrete collateral or bicollateral strands or bundles, the arrangement is called a eustele. A eustele occurs in the internodes of Equisetum and in many gymnosperms and flowering plants. Certain of the strands pass into the leaves as traces.

bicollateral vascular bundle (複並立維管束)

E. atactostele (不整中心柱)

found in monocots, in which the vascular tissue in the stem exists as scattered bundles

[morphology]

Leaf (葉)

Fig. Sectoin of leaf

cuticle upper epidermis (上面表皮)
palisade mesophyll (柵状組織)

vascular bandle = xylem + phloem

spongy mesophyll (海綿状組織)

air pore

lower epidermis (下面表皮)

stoma (気孔)
guard cell (孔辺細胞)

Vein (葉脈) penetrating the mesophyll layers of a leaf, consisting of vascular tissue, xylem and phloem

(pl. stomata or stomas)

Stoma (気孔)

____________Stoma open___________Stoma closed
Fig. Structure of stomata

Root (根)

Root anatomy is virtually the same for monocots, dicots and gymnosperms. The vascular tissue occurs in the center, which is surrounded by two rings of cells, the pericycle and endodermis, then the cortex and epidermis. The cell walls of the endodermis that are perpendicular to the root surface (i.e.. the radial and anticlinal walls) are sealed by a suberized band (Casparian strip). Root hair is extensions of the epidermal cells.

[ auxin ]

Root stimulator (発根促進剤)

auxin (= indole acetic acid)
willow: new shoot (12 cm long) with 2 leaves (Kikuchi et al. 1983)

immersed into water or 1-20 ppm NAA for 20 hours
transplanted the cuttages into a pot with kanuma soil (鹿沼土)
grown for three to four weeks

measurement: rooting ratio, root length

results: S. integra 100% of rooting, of which samples are collected in March and July