chapter 3 - plant structures Flashcards
Plant tissues
- meristems
- apical meristems
- lateral meristems
Meristems
dividing cells giving rise to various tissues
- actively dividing
- asexually giving rise to cells
Apical meristems
- produce primary tissue or primary growth
- growth in length
- give rise to dermal (single layer), ground, and vascular tissue
- vascular tissue: xylem and phloem
- on apex and tips
- only growth seen in herbaceous plants
Lateral meristems
- produce secondary tissue or secondary growth
- growth in width or girth
- gives rise to cork cambium and vascular cambium
Where does cork cambium develop from and what does it develop into?
- grows from lateral meristems
- secondary growth
- forms the periderm
- in woody plants produces cork cells to the outside
Vascular cambium
- secondary growth
- grows from lateral meristems
- forms secondary xylem and phloem
- seen in woody plants
- xylem to the inside and phloem to the outside
Dermal tissue
- gives rise to the epidermis of plants
- epidermis is covered by the cuticle (above ground)
Dermal tissue characteristics
- contains trichomes: hairlike extensions of epidermal cells
- contains stomates with guard cells
What is the function of trichomes on the epidermis
- increase surface area in the roots to increase moisture absorption
- above ground: help w water loss and help block the breeze for moisture loss
- help keep moisture on plant surface
- help prevent excess water loss when stomates are open
What is the function of stomates with guard cells in the epidermis
- gas exchange
- allows CO2 in
Secondary growth cork cambium
- called periderm and includes cork cells
- forms outer cork cells that create cork ridges
- pealing is caused by old cork getting separated as the stem gets bigger
Characteristics of cork
- malleable
- airtight seal
Cork Cambium functions
- needed to produce more cork cells bc it provides a line of defense from animals and fires (ground or grass)
- can help prevent moisture loss
What are annual rings
- new cork ring produced every year as the stem gets bigger
Ground tissue
- from apical meristems
- bulk of tissue in herbaceous plants
- gives rise to parenchyma, collenchyma, and sclerenchyma
Parenchyma
- type of ground tissue (apical)
- relatively thin-walled cells
- function in basic metabolism
- storage of starch
Collenchyma
- unevenly thickened walls of cellulose and pectin
- non-lignified (more flexible support)
- function in providing support for herbaceous plants
Sclerenchyma
- non-living at maturity
- evenly-thickened walls
- lignified (more rigid support)
- makes up seed coat
- functions in providing support for herbaceous plants
Vascular tissue
- conducting tissue
- xylem (primary)
- phloem (primary)
Conducting tissue
- type of vascular tissue
- bulk of tissue in woody plants
- xylem and phloem
Xylem
- non-living at maturity
- becomes a hollow tube that transports water from the roots up the plant
- contains tracheids and vessel elements
- lignified
- appear white in microscopes bc they are hollow
Tracheids
- longer, narrower
- more specialized for water movement
- found in all plants (gymnosperms and angiosperms)
Vessel elements
- shorter, wider
- only seen in angiosperms NOT in gymnosperms
Phloem
- living at maturity
- functions in movement of carbs (mainly sucrose) produced by photosynthesis
- made of sieve members and companion cells
- non-lignified
Sieve members
- part of phloem
- form a hollow lumen used for the passage of carbs
- living but contain few organelles
- have a companion cell next to it
Companion cells
- part of phloem
- next to sieve members
- living
- do metabolism for the sieve cells
- 1:1 ration
How do the conducting cells of xylem differ from sieve tube members and companion cells in phloem?
xylem: dead to function, transport water and minerals
phloem: living to function, transport carbs/sucrose
Stems
- support leaves for photosynthesis
- in herbaceous plants bulk tissue of stem is ground tissue
- in woody plants bulk tissue of stem is secondary vascular tissue
- surrounded by epidermis
monocot stem
- no pith
- vascular bundles of primary xylem and phloem are scattered
- rest of cells are ground tissue mainly parenchyma
dicot stem
- has a pith
- primary vascular bundles are arranged in a ring
- rest of cells are ground tissue mainly parenchyma
Woody Stems
- contain vascular cambium
- contain secondary xylem and phloem
- contain cork cambium
- contain bark
Vascular cambium in woody stems
- the inner lateral meristem
- produced secondary xylem to inside, secondary phloem to outside, and vascular rays (parenchyma cells) in both directions
Vascular rays
- made from vascular cambium
- produced in both directions
- made of parenchyma cells
- needed for lateral movement
- transport phloem contents to make cell walls
Secondary xylem
- forms annual rings made of springwood and summerwood
Cork cambium in woody stems
- the other lateral meristem
- produces periderm (corky, outer layer)
- feed for horses
Bark
- secondary phloem, cork cambium, and periderm
- anything OUTSIDE of the vascular cambium
Dendrochronology
- study of tree rings
- in drought rings are narrow
- in wetter climate rings are longer-wider
- used to study time and climate
Roots
- longitudinal section: root cap, zone of division, zone of elongation, zone of maturation
Zone of division
- cells divide
- cells are squared shape
Zone of elongation
- cells are elongated in a certain direction
- direction of elongation is dependent on cellulose microfibrils
Leaf internal anatomy
- mesophyll: packed with chloroplast for photosynthesis
- palisade mesophyll
- spongy mesophyll -
Palisade mesophyll
- tightly packed with chloroplast
- light dependent steps of photosynthesis occur here
- tightly packed and organized
- right below upper epidermis
- right above spongy mesophyll
Spongy mesophyll
- less packed to allow for gas exchange
- light independent steps of photosynthesis occur here
- right above lower epidermis
- right below palisade mesophyll
Lower epidermis
- where stomates are
- away from sunlight to prevent evaporation of water
Carnivorous plants
- typically found in bogs
- bc of acidity of bog plant can’t absorb mineral from soil
- eat ‘flesh’ or insects to getting minerals and nutrients that they cannot get from the soil
apical meristems
give rise to: primary growth
- dermal tissue: epidermis
- ground tissue: parenchyma, collenchyma, sclerenchyma
- vascular tissue: primary xylem and phloem
lateral meristems
give rise to: secondary growth
- cork cambium: periderm
- vascular cambium: secondary xylem and phloem
