Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8.
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Transcript of Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8.
Anatomy, Morphology, & Growth Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8of Angiosperms – Ch. 5-8
5 Differentiated Plant Cell Categories
1. Parenchyma
2. Collenchyma
3. Schlerenchyma
4. Water-conducting cells of the xylem
5. Sugar-conducting cells of the phloem
2. Collenchyma
• Usually grouped in strands to support young parts of plants without restraining growth
• Flexible, elongate with growing shoots
Vessel Elements
• End walls are perforated for free flow of water• More efficient as water conductors than tracheids
5. Sugar-conducting cells of the phloem
Sieve-tube members:
• Lack a nucleus, ribosomes, vacuole• Cells separated by perforated sieve plates –
allow sugar movement
1. Dermal tissue or epidermis
• Root hairs are specialized epidermal extensions• Secretes waxy cuticle of the leaf
2. Ground Tissue
• fills the space between dermal and vascular tissue systems.
• Diverse functions:
pith
cortexIn dicots:
3. Vascular Tissue
• function in transport between roots & shoots, and structural support of plant– Xylem:
– Phloem: Food transported to roots & non-photosynthetic parts such as the flowers
Three processes of development:
1. Growth =
2. Cellular differentiation = generation of different cell types
3. Morphogenesis – creation of body form & organization.
Meristems
• =
• Two types of meristems:1. Apical meristem –
2. Lateral meristems – extend lengthwise along the axis of the stem & roots. Responsible for growth in girth in older parts of the plant (called secondary growth). Exist only in perennials
Arrangement of Primary Tissues in Roots
1. Epidermis –
2. Stele –
3. Ground tissue – mostly parenchyma cells of the cortex – area between the stele & epidermis; stores food & takes up minerals.
• Endodermis – single cell layer between cortex & stele. Selective barrier for uptake of soil solution contents into vascular system.
Primary Growth of Shoots
• Bud = cluster of leaf primordia created by meristem. No internodes
• Lateral branches arise from axillary buds
Fig 35.16
pith
cortex
epidermis
phloem
xylem
Schlerenchyma cells
Eudicot/Gymnosperm stem cross section
Tissue arrangement of leaves
• 3 parts:
1. Upper & lower epidermis – tightly interlocked cells, secrete waxy cuticle. Contains stomata flanked by guard cells
2. Vascular tissue –
3. Mesophyll – ground tissue between upper & lower epidermis
Secondary Growth
• Two lateral meristems:
1. Vascular cambium – produces secondary xylem (= wood) & phloem
2. Cork cambium – replaces the epidermis with cork: tough, thick cover for stems, roots.
Secondary growth of stems
• Vascular cambium – layer of cells between primary xylem & primary phloem. Puts on successive layers of secondary phloem to outside & secondary xylem to inside =====> stem widens
• Wood = accumulation of secondary xylem. Dead at maturity, contains lignin
Three types of life cycles:
1. Annual –
2. Biennial – complete life cycle in two years (first year = vegetative, second year = reproductive). Some need a cold winter period to initiate flowering from vegetative state. Ex. carrots
3. Perennial – live year after year, do not die after reproduction. Examples: trees, shrubs, some grasses. Causes of death = fire, disease