Download plants – day 3

PLANTS – DAY 3
MONOCOT & DICOTS
INTRODUCTION
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There are different classes of
plants – one of these classes
of plants are called
angiosperms, and these plants
produce flowers.
Angiosperms can be further
divided into 2 subclasses:
Monocotyledoneae and the
Dicotyledoneae, aka
monocots and dicots
Names of 2 subgroups are
based on structure of their
seeds
SEEDS
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The seed, which surrounds the plant embryo and protects it
from desiccation in the uncertain conditions of a terrestrial
environment, is one of the adaptations that has allowed
plants to thrive as they gradually moved from water to land.
Each seed consists of an embryo, food source, and
protective outer coat; it can lie dormant for some time
before germinating, waiting until environmental conditions
are right
Monocots have only 1 seed leaf, cotyledon
Dicots have two cotyledon or seed leaves
Cotyledons store nutrients/carbohydrates that nourish the
embryo of the plant as it develops. Cotyledons are often
the first leaf to appear as the seed germinates
MONOCOT & DICOT SEEDS
EXAMPLES OF MONCOTS & DICOTS:
MONOCOTS:
Onion, corn, rice,
sugarcane
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DICOTS: tomatoes,
cabbage, apples,
peaches
SUMMARY OF DIFFERENCES:
MONOCOTS
DICOTS
TISSUE TERMS
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Vascular cambium/cylinder: meristematic tissue responsible for creating
new xylem and phloem tissue
Pith: the parenchyma tissue at the very center of roots AND stems.
Functions in storage of nutrients, carbohydrates and water
Cortex: parenchyma tissue surrounding the pith; made of rigid cells in roots
AND stems
Pericycle: a thin layer of lateral meristematic cells that surrounds the
vascular cylinder; helps for secondary roots to grow
Endodermis: layer of rectangular cells surrounding the vascular cylinder;
innermost layer of the cortex; regulates movement of water and minerals
Epidermis: the outermost layer of a multicellular plant experiencing growth
Vascular Bundles: collections of xylem and phloem tissue, separate from
other collections of cells, running longitudinally - includes xylem and phloem
ROOT TISSUE DIFFERENCES
Xylem in center
of root in an ‘X’
shape; phloem
is outside of
xylem
Vascular
bundles are
arranged in a
ring shape
MONOCOT ROOT CROSS SECTION
DICOT ROOT
CROSS SECTION
CORTEX
EPIDERMIS
STEMS – MONOCOT & DICOT
DICOT STEM CROSS SECTION
In herbaceous
dicots, bundles are
arranged in a ring
A thin layer of tissue called
vascular cambium between
xylem and phloem – can
appear as a hollow area in
the plant (buttercup)
MONOCOT STEM CROSS SECTION
MONOCOT STEM
VASCULAR BUNDLE
Herbaceous monocots
have vascular
bundles scattered
throughout the stem
(corn)