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Chapter #35~ Chapter #35~ Plant Structure and Plant Structure and GrowthGrowth
AngiospermsAngiosperms
Flowering PlantsFlowering Plants
– Two ClassesTwo Classes
Monocots- named for single Monocots- named for single cotyledoncotyledon
Dicots- named for two cotyledonsDicots- named for two cotyledons
– See structural differences (35.3)See structural differences (35.3)
Angiosperm structureAngiosperm structureTwo Main Systems- 3 basic organsTwo Main Systems- 3 basic organs– Root SystemRoot System– Shoot SystemShoot System
Stems and leavesStems and leaves
Each system depends upon one anotherEach system depends upon one another– Root system needs organic nutrients from the shoot Root system needs organic nutrients from the shoot
systemsystem– Shoot system needs water and minerals absorbed by root Shoot system needs water and minerals absorbed by root
system system
How does the Root and Shoot system exchange materials?How does the Root and Shoot system exchange materials?– Vascular tissueVascular tissue
Xylem- waterXylem- water
Phloem - FoodPhloem - Food
Root SystemRoot SystemRoots anchor plant and absorb minerals and waterRoots anchor plant and absorb minerals and water
Two typesTwo types
fibrous: mat of thin roots ( threadlike)fibrous: mat of thin roots ( threadlike)– Grasses and many monocots have these Grasses and many monocots have these – Roots are usually concentrated in the upper few Roots are usually concentrated in the upper few
centimeters of soil- help with erosion centimeters of soil- help with erosion
taproot: one large, vertical root with many smaller taproot: one large, vertical root with many smaller lateral rootslateral roots
– Most dicots have theseMost dicots have these
Root hairs- increase surface area and help with Root hairs- increase surface area and help with absorptionabsorption
Fig. 35-4
Prop roots
“Strangling”aerial roots
Storage roots
Buttress roots
Pneumatophores
Shoot SystemsShoot SystemsStemsStems (shoot system) (shoot system) – nodes: leave attachment nodes: leave attachment – internodes: stem segments internodes: stem segments – axillary bud: dormant, vegetative potential axillary bud: dormant, vegetative potential
– terminal bud: apex of young shoot terminal bud: apex of young shoot – apical dominance: inhibits axillary budsapical dominance: inhibits axillary budsLeavesLeaves (shoot system) (shoot system)– bladeblade– PetiolePetiole– Monocots have parallel veins and dicots have Monocots have parallel veins and dicots have
branched veinbranched vein
Fig. 35-5Rhizomes
Bulbs
Storage leaves
Stem
Stolons
Stolon
Tubers
Fig. 35-6
( Simple leaf
Compoundleaf
(b)
Doublycompoundleaf
(c)
Petiole
Axillary bud
PetioleAxillary bud
LeafletPetioleAxillary bud
Fig. 35-7Tendrils
Spines
Storageleaves
Reproductive leaves
Bracts
Types of Plant TissuesTypes of Plant TissuesDermalDermal (epidermis): single layer of cells for protection (epidermis): single layer of cells for protection cuticlecuticle
Vascular Vascular (material transport)(material transport)– xylem: water and dissolved minerals roots to shootsxylem: water and dissolved minerals roots to shoots
tracheids & vessel elements: xylem elongated tracheids & vessel elements: xylem elongated cells dead at maturitycells dead at maturity
– phloem: food from leaves to roots and fruitsphloem: food from leaves to roots and fruits
sieve-tube members: phloem tubes alive at sieve-tube members: phloem tubes alive at maturity capped by sieve plates; companion cells maturity capped by sieve plates; companion cells (non-conducting) connected by plasmodesmata(non-conducting) connected by plasmodesmata
Ground Ground (photosynthesis, storage, support): pith and (photosynthesis, storage, support): pith and cortexcortex
Plant Tissue Cell Types Within Plant Tissue Cell Types Within TissuesTissuesParenchymaParenchyma
– primary walls thin and flexibleprimary walls thin and flexible– no secondary wallsno secondary walls– large central vacuolelarge central vacuole– most metabolic functions of plant (chloroplasts)most metabolic functions of plant (chloroplasts)
CollenchymaCollenchyma– unevenly thick primary walls used for plant support unevenly thick primary walls used for plant support – no secondary walls ; no ligninno secondary walls ; no lignin
SclerenchymaSclerenchyma– support element strengthened by secondary cell walls with support element strengthened by secondary cell walls with
lignin (may be dead; xylem cells)lignin (may be dead; xylem cells)– fibers and sclereids for support fibers and sclereids for support
Plant GrowthPlant GrowthLife CyclesLife Cycles– annualsannuals: 1 year (wildflowers; food crops): 1 year (wildflowers; food crops)– biennialsbiennials: 2 years (beets; carrots): 2 years (beets; carrots)– perennialsperennials: many years (trees; shrubs): many years (trees; shrubs)MeristemsMeristems– apicalapical: tips of roots and buds; primary growth: tips of roots and buds; primary growth– laterallateral: cylinders of dividing cells along length : cylinders of dividing cells along length
of roots and stems; secondary growth (wood)of roots and stems; secondary growth (wood)– Primary growth is length vs. secondary Primary growth is length vs. secondary
growth is girthgrowth is girth
Primary growth in rootsPrimary growth in rootsRootsRoots
root caproot cap-protection of -protection of meristemmeristem
zone of cell divisionzone of cell division- - primary (apical) meristemprimary (apical) meristem
zone of elongationzone of elongation- cells - cells elongate; pushes root tipelongate; pushes root tip
zone of maturationzone of maturation- - differentiation of cells differentiation of cells (formation of 3 tissue (formation of 3 tissue systems)systems)
Primary Tissues of RootsPrimary Tissues of RootsSteleStele- the vascular bundle where both xylem and - the vascular bundle where both xylem and phloem developphloem develop
PithPith- central core of stele in monocot; parenchyma - central core of stele in monocot; parenchyma cellscells
CortexCortex- region of the root between the stele and - region of the root between the stele and epidermis (innermost layer: epidermis (innermost layer: endodermisendodermis))
Lateral rootsLateral roots- arise from - arise from pericyclepericycle (outermost layer of (outermost layer of stele); just inside endodermis, cells that may become stele); just inside endodermis, cells that may become meristematicmeristematic
Primary Tissues of StemsPrimary Tissues of Stems
Vascular bundles (xylem and phloem)Vascular bundles (xylem and phloem)
Surrounded by ground tissue (xylem faces pith Surrounded by ground tissue (xylem faces pith and phloem faces cortex)and phloem faces cortex)
Mostly parenchyma; some collenchyma and Mostly parenchyma; some collenchyma and sclerenchyma for supportsclerenchyma for support
Primary Tissues of LeavesPrimary Tissues of LeavesEpidermis/cuticle (protection; desiccation)Epidermis/cuticle (protection; desiccation)
StomataStomata (tiny pores for gas exchange and (tiny pores for gas exchange and transpiration)/transpiration)/guard cellsguard cells
MesophyllMesophyll– ground tissue between upper and lower epidermis ground tissue between upper and lower epidermis
(parenchyma with chloroplasts)(parenchyma with chloroplasts)– palisade (most photosynthesis) and spongy (gas palisade (most photosynthesis) and spongy (gas
circulation)circulation)
Secondary GrowthSecondary GrowthTwo lateral meristemsTwo lateral meristems– vascular cambium vascular cambium -produces secondary xylem -produces secondary xylem
(wood) and secondary phloem (diameter (wood) and secondary phloem (diameter increase; annual growth rings)increase; annual growth rings)
– cork cambium cork cambium -produces thick covering that -produces thick covering that replaces the epidermisreplaces the epidermis
produces cork cellsproduces cork cells
– barkbark-all tissues external to vascular cambium -all tissues external to vascular cambium (phloem plus periderm)(phloem plus periderm)
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