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Structures, distribution and function in Tissues of Plants 第二节 植物组织结构、分布与功能. The plant body consists of integrated structures called organs, ( 器官) such as roots, stems, leaves, petals etc . which in turn are made of tissues .
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Structures, distribution and function in • Tissues of Plants • 第二节 植物组织结构、分布与功能 The plant body consists of integrated structures called organs, (器官)such as roots, stems, leaves, petals etc. which in turn are made of tissues. Concept: Tissues are cell complexes which are similar in origin and structure, and are of same functions.
Tissues may be simple (consisting of one cell type only) as parachyma (薄壁细胞), collenchyma (厚角组织)or sclerenchyma (厚壁细胞), or complex (consisting of two or more cell types) as in the case of epidermis (表皮), xylem(木质部) and phloem(韧皮部). Complex tissues 复合组织 Simple tissue 简单组织
Plants consist of four basic kinds of Tissues systems: Meristematic 分生组织 Ground 基本组织(薄壁与机械) Dermal 保护组织 Vascular 输导组织 Conducting tissue Secretory structure 分泌结构 Mature tissues 成熟组织
1. Meristem 分生组织 A specialized regions of active cell division called meristem, Including: 按位置分: Apical meristem 顶端分生组织 Lateral meristem 侧生分生组织 Intercalary meristem 居间分生组织
According their origin and characters 按来源与性质分, including: promeristem 原分生组织 primary meristem 初生分生组织 secondary meristem 次生分生组织 Apical meristems
Secondary meristem 次生分生组织 Secondary meristem cells are derived from mature Parenchyma cells ( 薄壁组织细胞).
2. Mature tissues 成熟组织 2.1. Parenchyma cells have thin primary walls 薄壁组织 Ground tissues (基本组织) are typically parenchyma. Many parenchyma cells are Isodiametric (等径的). A transverse section (横切面)of corn (Zea mays) internode showing ground parenchyma in which vascular bundles are embedded.
Parenchyma 薄壁组织 Shown here are potato tuber (Solanum sp.) parenchyma cells The cells show small intercellular spaces (细胞间隙) between them.
1) Absorptive tissue 吸收组织 Epidermis and root hairs in root hair region
2) Assimilating tissue 同化组织 In green parts of plant
4) Ventilaiting tissue 通气组织 In hydrophytes (水生植物) and wetland plants(湿生植物).
2.2. Mechanical tissues 机械组织 There are two types: Collenchyma and sclerenchyma 厚角组织 厚壁组织 1)Collenchyma cells elongated with non- Lignified(非木质化), unevenly thickened Primary walls. Angular collenchyma has greatest wall thickenings where cells meet in corners. Petiole of celery (Apium sp.) 芹菜叶柄切片.
Electron microscopy reveals greater detail. This is another view of the angular collenchyma from the petiole (叶柄)of Rumex confertus(酸摸)
Cross section and vertical section of Collenchyma 厚角细胞的横切与纵切面
2)Sclerenchyma 厚壁组织 Brachysclereids (石细胞) and fibre (纤维) Brachysclereids are isodiametric(等径的). Show ramified pits (分枝状纹孔) 1 = primary wall, 2 = secondary wall, 3 = ramified pit, 4 = cell lumen (细胞腔)
Fibre (纤维): A. Phloem fibres (韧皮纤维) may be no lignified (非木质化) , and longer & flexible (柔韧性) .
B. Xylem fibres (木纤维) is lignified (木质化), and shorter & fragility (脆弱).
Vertical section of fibre 纤维细胞的纵切面
2.3. Dermal or Protective tissue 保护组织 Epidermis 表皮 Periderm 周皮 Primary protective tissue secondary protective tissue 初生保护组织 次生保护组织
1). Epidermis 表皮 Characters of leaf Epidermis 叶表皮特征 Epidermis cells Stomata apparatus Trichomes
A. Epidermal Cells (表皮细胞) highly acuolated(液泡化), very close in order , no intercellular spaces (细胞间隙). Adaxial (近轴)(upper) & abaxial (远轴)(lower) epidermises are different in leave.
B. Stomata apparatus 气孔器 consist of two guard cells (保卫细胞)and stomata (气孔), sometime including subsidiary cells (副卫细胞) Light microscopy of leaf surface, Chloroplasts found in guard cells
C. Trichomes on epidermis 表皮毛状物 Single cell 单细胞的 Ramiform 分枝的
Cuticle (外被)on epidermis C = cuticle(外被); CP = cytoplasm(细胞质); EW = epicuticular wax (蜡质); PW = primary cell wall
2) Periderm (周皮) ------ secondary protective tissue (次生保护组织) Phellem 木栓层 (厚壁细胞) Cork cambium 木栓形成层 (次生分生组织) Phelloderm 栓内层 (薄壁细胞)
Development of peridermand Lenticel structure 周皮发育与皮孔结构 • 周皮发育(A) • 和皮孔(B) • 木栓形成层开始发生; • 2.表皮; • 3.木栓形成层; • 4. 木栓层; • 5. 栓内层; • 6.皮层薄壁细胞; • 7.补充细胞
2.4. Secretory structure 分泌结构 Concept:凡能产生分泌物质的有关细胞或特化的细胞组合,总称为分泌结构。 这些物质聚积在细胞内、胞间隙或腔道中,或通过一定的细胞组成的分泌结构排出体外,这种现象称为分泌现象。 许多分泌物具重要经济价值,如橡胶、生漆、芳香油、蜜汁等。
Thear are two kinds of structures. 根据分泌物质是分泌到体外还是体内,可分为外分泌结构和内分泌结构。 1)外分泌结构(external secretory structure) 主要分布在植物体表,如腺毛、腺鳞、蜜腺、排水器等。
2)内分泌结构(internal secretory structure) 其分泌物积聚于植物体的细胞内、胞间隙、囊腔或管道内。常见的有分泌细胞、分泌腔或分泌道和乳汁管。 Secretory cells
2.5 Conducting tissue (输导组织) 1)Vessels (导管)composed of vessel elements only appear in angiosperm. 导管由导管分子组成,仅存在于被子植物中。 A. Developmental process (发育过程)
B. Different types of vessels (不同类型的导管) Primitive 原始 ---------------------- evolutionary 进化
Various secondary thickenings & pittings in vessel elements 导管分子的各种次生加厚 网纹 reticular 环纹 annular Scalariform pits in Laurelia novaezealandiae as seen with SEM.
C. Variation of perforation Plates on end wall 端壁上穿孔板的变化 Simple perforation 单穿孔 梯纹穿孔Scalariform perforation 属复穿孔
D. 侵填体(tylosis):突入导管内生长的囊泡状结构,含有单宁、晶体、树脂和色素等物质,能增强抗腐力,防止病菌侵害,增强木材的坚实度和耐水性。
2) Tracheids (管胞) appear in angiosperm, gymnosperm and fern. 管胞存在于被子植物,裸子植物和蕨类植物 A. 管胞是一种细长、两头尖、孔径小的输导分子;也进行次生加厚,但端壁不形成穿孔。 Development of tracheids 管胞的发育
Structure of pit 纹孔的结构 Bordered pits Simple pits B. 管胞侧壁上的纹孔
导 管 与 管 胞 管 胞 导 管
Conductive pathway of vessels and tracheids 导管与管胞输导途径示意 穿孔板 纹孔与纹孔对 穿孔板