第二十五章: 植物的組織 前言

Mount Saint Helens Eruption Volcano is located in southwestern Washington state In 1980 it erupted, blowing 500 million metric tons of rock and ash outward Ash and lava devastated about 40,500 acres of what had been forest

Recovery Plants moved into the empty habitat almost immediately Fireweed and blackberry were early colonists In less than ten years, willow and alders were on the scene

Success of the Angiosperms The angiosperms are seed-bearing vascular plants In terms of distribution and diversity, they are the most successful plants on Earth The structure and function of this plant group help explain its success

Plant Life Histories Annuals complete life cycle in one growing season Biennials live for two seasons; flowers form in second season Perennials grow and produce seeds year after year

植物的綜觀 枝梢(Shoots) 包括: 莖 葉 花(生殖枝) 根 (Roots)  

蕃茄 典型的被子植物

三種植物的組織系統 基本組織系(Ground tissue system) 維管組織系(Vascular tissue system) 表層組織系(Dermal tissue system)

分生組織(Meristems): 組織起源的地方 在莖或根的頂尖上形成 初生分生組織: 既,表層分生組織, 基本分生組織,原始形成層等 次生生長組織: 圍環的增加 維管束形成層(Vascular cambium) 木栓形成層(Cork cambium),既皮層

Cutting Specimens radial transverse tangential

Meristems Regions where cell divisions produce plant growth Apical meristems Lengthen stems and roots Responsible for primary growth Lateral meristems Increase width of stems Responsible for secondary growth

Apical Meristems Lengthen shoots and roots Cells that form at apical meristems Protoderm Ground meristem Procambium activity at meristems new cells elongate and start to differentiate into primary tissues

Lateral Meristems Increases girth of older roots and stems Cylindrical arrays of cells vascular cambium cork cambium thickening

植物組織的型態 單純組織 複合組織

Made up of only one type of cell Simple Tissues Made up of only one type of cell Parenchyma (薄璧組織) Collenchyma (厚角組織) Sclerenchyma (厚璧組織)

植物組織的型態

Parenchyma: A Simple Tissue 柔軟,濕潤之出生生長的 細胞;有分生能力 Comprises most of a plant’s soft primary growth Cells are pliable, thin walled, many sided Cells remain alive at maturity and retain capacity to divide Mesophyll is a type of parenchyma that contains chloroplasts

Collenchyma: A Simple Tissue Specialized for support for primary tissues Cells are elongated, with walls (especially corners) thickened with pectin Makes stems strong but pliable Cells are alive at maturity

Collenchyma: A Simple Tissue Supports mature plant parts Protects many seeds Cells have thick, lignified walls and are dead at maturity Two types: Fibers: Long, tapered cells Sclereids: Stubbier cells

厚角組織(Collenchyma): 提供出生組織的柔軟支撐, 具伸長形狀,有果膠質連接 的加厚細胞璧

厚璧組織(Sclerenchyma): 支撐成熟植物體, 保護種子, 有木質素, 厚璧組織由: 厚璧細胞(Sclereids)及 纖維(Fibers)組成

棉花種子的纖維 亞麻莖內的強壯纖維

維管束組織(Vascular tissue) Complex Tissues 複合組織 維管束組織(Vascular tissue) 皮層組織(Dermal tissue) Composed of a mix of cell types Xylem Phloem Epidermis

Xylem Conducts water and dissolved minerals Conducting cells are dead and hollow at maturity vessel member tracheids

Phloem: A Complex Vascular Tissue sieve plate Transports sugars Main conducting cells are sieve-tube members Companion cells assist in the loading of sugars sieve-tube member companion cell

維管束組織(Vascular tissue):輸送 木質部(Xylem) 導管(Vessel members) 假導管(Tracheids) 韌皮部(Phloem) 篩管細胞(Sieve-tube members) 伴細胞(Companion cells)

木質部(Xylem) 韌皮部(Phloem) 導管(Vessel members) 假導管(Tracheids) 篩管細胞 伴細胞

Epidermis (皮層組織): A Complex Plant Tissue Covers and protects plant surfaces Secretes a waxy, waterproof cuticle In plants with secondary growth, periderm replaces epidermis

單子葉植物(Monocot)和雙子葉植物(Dicot) 相同組織，不相同的特徵 1 cotyledon 2 cotyledons 4 or 5 floral parts 3 floral parts Netlike veins Parallel veins 3 pores 1 pore Vascular bundles dispersed Vascular bundles in ring

枝梢的初生構造: 莖和葉如何形成與內部構造

莖內部構造: Dicot

Dicot

Adapted for Photosynthesis Leaves are usually thin High surface area-to-volume ratio Promotes diffusion of carbon dioxide in, oxygen out Leaves are arranged to capture sunlight Are held perpendicular to rays of sun Arrange so they don’t shade one another

細看葉子 葉子間的相似與相異處 葉子的細部構造 葉子的神奇用處與誤用

單葉 複葉

葉子的細部構造

Mesophyll: Photosynthetic Tissue A type of parenchyma tissue Cells have chloroplasts Two layers in dicots Palisade mesophyll Spongy mesophyll

Leaf Veins: Vascular Bundles Xylem and phloem; often strengthened with fibers In dicots, veins are netlike In monocots, they are parallel

葉子的神奇用處與誤用

初生根的構造 主根系和鬚根系 根的內部構造

主根系 (tap root system) 鬚根系 (Fibrous root system)

根的內部構造

Internal Structure of a Root Outermost layer is epidermis Root cortex is beneath the epidermis Endodermis, then pericycle surround the vascular cylinder In some plants, there is a central pith

Function of Endodermis Ring of cells surrounds vascular cylinder Cell walls are waterproof Water can only enter vascular cylinder by moving through endodermal cells Allows plant to control inward flow

毛莨(a Dicot) 中心柱

玉米(a Monocot) 中心柱

柳 樹 側 根 的 形 成 過 程

Root Hairs and Lateral Roots Both increase the surface area of a root system Root hairs are tiny extensions of epidermal cells Lateral roots arise from the pericycle and must push through the cortex and epidermis to reach the soil new lateral root

積聚次生生長: 木本植物 一年生植物(Annuals) 多年生植物(Perennials)

Secondary Growth Occurs in all gymnosperms, some monocots, and many dicots A ring of vascular cambium produces secondary xylem and phloem Wood is the accumulation of these secondary tissues, especially xylem

胡桃的莖部剖面圖

Vascular Cambium Lateral meristem One or two cells thick Divides in two directions Cells formed to the outside become secondary phloem Cells formed to the inside become secondary xylem

維管束植物形成層活動模式圖

Woody Stem periderm (consists of cork, cork cambium, and secondary cortex) secondary phloem HEARTWOOD SAPWOOD BARK vascular cambium

木材的切片

Annual Rings Concentric rings of secondary xylem Alternating bands of early and late wood Early wood Xylem cells with large diameter, thin walls Late wood Xylem cells with smaller diameter, thicker walls

Types of Wood Hardwood (oak, hickory) Softwood (pine, redwood) Dicot wood Xylem composed of vessels, tracheids, and fibers Softwood (pine, redwood) Gymnosperm wood Xylem composed mostly of tracheids Grows more quickly

year 1 2 3 Fig. 26.23, p. 433 Fig. 26.21b, p. 433