Chapter 35 Notes
Plant Structure and
Growth
Concept 35.1
Plants are made up of two main systems:
the root system and shoot system
Plants have three basic organs
- roots
- stems
- leaves
Concept 35.1
Root system
- anchor plants in the soil
- absorb minerals and water
- store food
Monocots have fibrous roots: mat of
thin roots that spread out below the soil
surface
Concept 35.1
Dicots have a taproot: one large vertical
root that produces lateral branch roots
Root hairs: increase surface area and
help absorption of water/minerals
Adventitious roots: roots that are
above ground; extend from stem
Concept 35.1
Shoot system
Stem
- an alternating system of nodes (place
where leaves are attached) and
internodes (the stem between the
nodes)
- auxiliary bud: structure that forms a
branch
Concept 35.1
- terminal bud: place of growth of a
young shoot
- apical dominance: growth focuses
on the terminal bud; inhibits the axillary
bud
Concept 35.1
Concept 35.1
Leaves
- main photosynthetic organ of plants
- consist of a flattened blade and a
petiole (stalk that join to the node of
the stem)
- monocots have parallel veins in leaves
- dicot leaves have a multibranched
network of veins
Concept 35.1
Concept 35.1
Plant organs are composed of three tissue
systems: dermal, vascular, and ground
Dermal tissue
- single layer of tightly packed cells that
covers and protects all young parts of
the plants
- for the cuticle
Concept 35.1
Vascular tissue
- involved in the transport of materials
between the root and the shoot
- xylem: moves water and dissolved
minerals upward from roots
- tracheids and vessel elements
are elongated cells that are dead at
functional maturity
Concept 35.1
Concept 35.1
- phloem: moves food made by leaves
to the roots
- sieve-tube members transport
sucrose and other organic materials
- sieve plates help move fluid from
cell to cell
- companion cell: assist the STM
Concept 35.1
Concept 35.1
Ground tissue
- tissue that is neither dermal nor
vascular
- in dicots, divided into the pith
(internal to the vascular tissue) and the
cortex (external to vascular tissue)
- photosynthesis, storage, and support
Concept 35.1
Concept 35.1
Plant tissues are composed of three basic
cell types: parenchyma, collenchyma,
and sclerenchyma
Parenchyma cells
- have 1o cell walls, but lack 2o
- typical plant cell; least specialized
- perform most metabolic functions of
the plant
Concept 35.1
Collenchyma cells
- thicker 1o cell walls
- support young parts of the plant shoot
- provide support without restraining
growth
Concept 35.1
Sclerenchyma cells
- support; form thick 2o cells that are
strengthened by lignin
- occur in areas of plants that have
stopped growing
- dead at functional maturity
- ex. xylem cells
Concept 35.1
Concept 35.2
Most plants grow as long as the plant
lives (indeterminate growth)
Annuals: complete their life cycle in one
year
Biennial: life of the plant spans two
years
Perennials: live many years
Concept 35.2
A plant is capable of indeterminate
growth because it always has
embryonic tissue called meristems
- cells that divide to produce additional
cells
Plant growth depends on the location of
the meristems
Concept 35.2
Apical meristems: located at the tips of
roots and in the buds of shoots
Primary growth: enables roots to grow
through soil and shoots to increase their
exposure to sunlight
Secondary growth: thickening of the
roots and shoots
- formed by lateral meristems
Concept 35.2
Concept 35.3
Primary growth of roots
The root tip is covered by a root cap
The zone of cell division include the
apical meristem and the 3 primary
meristems (protoderm, procambrium,
and ground meristem)
- produce the three 1o tissue systems
Concept 35.3
Concept 35.3
Primary growth of shoots
The apical meristem of the shoot tip gives
rise to the 3 primary meristems that
turn into the different tissue systems
Vascular tissue runs through the stem in
strands called vascular bundles
- surrounded by ground tissue
Concept 35.3
Concept 35.3
In dicots, the vascular bundles are
arranged in a ring, with the pith inside
the ring, the cortex is outside
In monocots, the vascular bundles are
scattered throughout the ground tissue
Concept 35.3
Concept 35.3
Concept 35.3
Tissue organization of leaves
The epidermis is composed of tightly
interlocked cells
- stomata: tiny pores that allow for
gas exchange w/ the help of guard cells
The ground tissue is sandwiched between
the upper and lower epidermis in the
mesophyll
Concept 35.3
- the mesophyll consists of parenchyma
cells w/ chloroplasts
The vascular tissue also flows through the
leaf from the stem
- contains the xylem and phloem
Concept 35.3