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ANATOMY OF A PLANT
A plant is a member of the kingdom Plantae, a living organism that utilizes photosynthesis, a process in
which energy from sunlight is converted to chemical energy (food). Plants are at the base of the food web
and are autotrophs (or producers - organisms that make their own food). Plants vary greatly in size, shape,
and the type of environment in which they live.
Structure and Function: Roots anchor the plant in the ground and absorb water and mineral nutrients
from the ground. Leaves contain chloroplasts, in which photosynthesis occurs. Carbon dioxide is
absorbed through pores in the leaves; oxygen is produced as a by-product of photosynthesis and is
released. Plant cells have a supportive cellulose cell wall (unlike animal cells which lack cellulose).
Angiosperms - Are flowering plants. They produce seeds enclosed in fruit (an ovary). Two types of
angiosperms: Monocots and Dicots
Monocots and Dicots
Chart showing Differences
Monocot
Dicot
SEED
Monocots have only one seed leaf inside the seed coat.
It is often only a thin leaf, because the endosperm to
feed the new plant is not inside the seed leaf.
Dicots have two seed leaves inside the seed coat. They
are usually rounded and fat, because they contain the
endosperm to feed the embryo plant.
GERMINATION
Homeria
Lilium
Gloriosa
Eryngium
When a monocot seed germinates, it produces a single
leaf. It is usually long and narrow, like the adult leaf.
Even when it is quite a round shape, there is only one
seed leaf in a monocot.
Sanguisorba
Cladanthus
When a dicot germinates, it produces two seed leaves.
They contain the food for the new plant, so they are
usually fatter than the true leaves. The first true leaves
are often a different shape.
LEAVES
Washingtonia
Clivia
Canna
The leaves of monocots are often long and narrow, with
their veins in straight lines up and down the leaf.
Sometimes, the veins run from the centre of the leaf to
the edge, parallel to one another.
Malva
Rosa
Campanula
Leaves of dicots come in many different shapes and
sizes. The veins go from the central midrib to the edge of
the leaf, crossing and joining to form a netted pattern all
over the leaf.
STEM & ROOTS
Stem
Sheath
Root
Stem
The stems of monocots are usually unbranched and
fleshy. They do not grow thicker from year to year. New
leaves often grow wrapped in a protective sheath formed
by the older leaf. The roots of dicots are usually short
and stringy. Dicots often have bulbs.
Stipule
Root
The stems of dicots are usually tough. They can grow
wider each year and are often branched. They sometimes
have stipules at the base of the leaf. The root is often a
single long tap root with smaller roots growing from it.
FLOWER
Cyrtanthus
Pleione
Agapanthus
The parts of the flower of monocots are in threes. The
sepals are often the same colour as the petals, making it
look as if the flower has six petals. There are usually the
same number of stamens as petals.
Oenothera
Epilobium
Geranium
The flowers of dicots usually have flower parts in fours
or fives. The calyx is a separate ring of sepals under the
corolla, and is usually green.
SEEDPOD
Iris
Anthericum
Hedychium
The seed pods or fruits of monocots usually have three
parts. The seeds are often large and fleshy. The largest
seed in the world, the Coco-de-Mer, and the smallest
seeds in the world, Orchid seeds, are both monocot
seeds.
Lychnis
Erigeron
Clitoria
The seedpods or fruits and the seeds of dicots are very
variable in shape, size and texture. The seedpod can have
any number of chambers, from none to many. There are
often more seeds in a seedpod than in a monocot
seedpod.
Gymnosperm - Gymnosperms (meaning "naked seeds") are seed-bearing plants that don't produce
flowers. These plants release pollen into the air to the female ovule, causing fertilization. Their seeds
develop without a protective covering. They are are plants that have seeds but no flowers. The seeds of
these plants are on cones or in cups. Most gymnosperms are evergreen. Gymnosperms include conifers,
cycads and the ginkgo.
ANATOMY OF A PLANT
Axil - The angle between the upper side of
the stem and a leaf, branch, or petiole.
Axillary bud - A bud that develops in the
axil.
Flower - the reproductive unit of
angiosperms.
Flower stalk - the structure that supports the
flower.
Internode - the area of the stem between any
two adjacent nodes.
Lateral shoot (branch) - an offshoot of the
stem of a plant.
leaf - an outgrowth of a plant that grows from
a node in the stem. Most leaves are flat and
contain chloroplasts; their main function is to
convert energy from sunlight into chemical
energy (food) through photosynthesis.
node - the part of the stem of a plant from which a leaf, branch, or aerial root grows; each plant
has many nodes. Label the two lower nodes (the first and second nodes) on the plant diagram.
petiole - a leaf stalk; it attaches the leaf to the plant.
root - a root is a plant structure that obtains food and water from the soil, stores energy, and
provides support for the plant. Most roots grow underground.
root cap - a structure at the ends (tips) of the roots. It covers and protects the apical meristem
(the actively growing region) of the root.
stem - (also called the axis) is the main support of the plant.
tap root - the main root of some plants; the tap root extends straight down under the plant.
terminal bud - a bud located at the apex (tip) of the stem. Terminal buds have special tissue,
called apical meristem, consisting of cells that can divide indefinitely.
Functions of the Root System
- Underground (usually)
- Anchor the plant in the soil
- Absorb water and nutrients
- Conduct water and nutrients
- Food Storage
Functions of the Shoot System
- Above ground (usually)
- Elevates the plant above the soil
- Many functions including: photosynthesis, reproduction & dispersal of food and water
conduction.
Note: the shoot system includes the leaves and the reproductive organs, although these will be covered
in more detail separately.