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Question: What are the characteristics of the plant kingdom?
THE PLANT KINGDOM
Plants are multicellular autotrophs that are mostly found on land and are very different
from their algae ancestors.
There are four major challenges to plants living on land:
1. Obtaining water and other nutrients — most plants have shoots and roots — roots
absorb water and essential minerals from soil; shoots bear leaves. Roots and shoots are
made of vascular tissue, a system of tube-shaped cells that branches throughout plant.
2. Supporting their bodies — plants can only stand upright because of the production of
lignin, a chemical that hardens the plants’ cell walls.
3. Maintaining moisture — plants cellular processes must take place in an aqueous
environment, therefore they have adapted a waxy cuticle which acts as a waterproof
layer coating the leaves and other above ground parts. Stomata, or microscoping pores
in leaf’s surface also prevent water loss by evaporation.
4. Reproduction — plants had to adapt to protect the gametes (eggs/sperm) from drying
out and had to have some means for dispersal such as pollen grains carried by wind or
animals.
CLASSIFYING
PLANTS
NON-VASCULAR
Plants that lack a well- developed
system for transporting water
and materials
VASCULAR
plants with true vascular
tissue
Plants have complex life cycles that include two different stages:
Sporophyte stage — plant produces spores, tiny cells that can grow into new organisms;
develops into plants other phase, called the gametophyte.
Gametophyte stage — plant produces two kinds of sex cells: sperm cells and egg cells
Question: What structural adaptation allows pterophytes to grow larger than bryophytes?
PLANTS WITHOUT SEEDS
Nonvascular Plants
Bryophytes — mosses and their relatives, are described as non-vascular plants because
they lack the lignin-hardened vascular tissue that offers vascular plants
support.
— low-growing plants that live in most areas where they can absorb water
and nutrients directly from ground.
 Mosses — over 10,000 species; mat of moss contains many gametophyte plants. The
sporophyte generation grows out of gametophyte.
 Hornworts — bryophytes named for their hornlike sporophytes, which grow from
their parental gametophyte.
 Liverworts — bryophytes named for liver-shaped appearance of the gametophyte
Seedless Vascular Plants
Pteridophytes — have lignin-hardened support tissues, which include the waterconducting cells of vascular tissue along with vascular tissue
specialized for transporting sugar
 Ferns — over 12,000 species, have leaves called fronds divided into many smaller
parts that look like small leaves.
 Club “mosses” — have vascular tissue, unlike true mosses; common on forest floors
of the north-eastern United States.
 Horsetails — generally grow in marshy, sandy areas; very few species on Earth
today, stems contain gritty substance, silica, which made plant helpful when
scrubbing pots and pans back in the day.
Question: Why are seeds an important structural adaptation?
SEED PLANTS
Seed plants share two important characteristics – they have vascular tissue, and they
use pollen and seeds to reproduce.
Pollen grain — contains the male gametophyte consisting of sperm cells, nutrients and a
protective outer coating.
Ovule — sporophytic structure which contains the female gametophyte, which produces
the egg cell. The ovule forms the seed after fertilization.
Seed — has three main parts – an embryo, stored food and a seed coat
Embryo — young plant that develops from the zygote, or fertilized egg.
In all seeds, the embryo has one or more seed leaves, or cotyledons, which sometimes
store food.
Germination — occurs when embryo begins to grow, after dispersal and pushes out of
seed.
Seed dispersal, or scattering of seeds, occurs by other organisms, water, wind or selfeject mechanisms.
Seed plants are divided into two groups :
Gymnosperms
Plants whose seeds are NOT protected by
fruit
—have needle-like or scale-like leaves, and
deep-growing root systems: Cycadophyta,
Ginkophyta, Gnetophyta & Coniferophyta
Angiosperms
Plants that produce seeds protected by
fruit
Fruit — includes ripened ovary of a
flower
Anthophyta — flowering plants
Question: What is the advantage of flowers having bright patterns of coloration surrounding
reproductive structures?
FLOWERING PLANTS
Flowers come in all shapes and sizes and of course, color. But despite all the variety,
flowers have on function – reproduction.
Flower — reproductive structure of an angiosperm.
Parts of a Flower:
 Sepals — leaflike structures that cover and protect flower bud before it opens.
 Petals — most colorful part of flower that help attract and guide pollinators toward
center.
 Stamens — male reproductive parts which have a thin stalk called filament on which
the anther sits on top (where pollen is produced).
 Pistil — female reproductive organ; top of pistil is sticky top called stigma which is
connected to ovary by slender tube called the style. Ovary is where ovules grow into a
seed if fertilized.
Angiosperms are divided into two major groups:
MONOCOTS
DICOTS
Seeds
Single
cotyledon
Two
cotyledons
Leaves
Parallel
Veins
Branched
Veins
Flowers
Floral parts in
multiples of 3
Floral parts in
multiples of
4 or 5
Stems
Vascular bundles
scattered
Vascular bundles
in a ring
Roots
Fibrous
Roots
Taproot
Question: What are the three main organs of seed plants?
ROOTS, STEMS AND LEAVES
Roots — plant organ that anchors a plant to the ground, absorbs water and dissolved
minerals and contains vascular tissue to move water and minerals to stem.
Two main types of root systems:
1. Taproot – single, thick structures with smaller branching roots.
Ex. carrots and beets
2. Fibrous root – small branching roots that grow from a central point.
Ex.
grassplants?
Question: How do hormones
affect
Stems — carry substances between plant’s roots and leaves. Also provides support
for plants and holds up leaves to sunlight. Consists of three tissue systems: dermal,
vascular and groundPLANT
tissue. RESPONSES AND GROWTH
Tropism
plant’s district
growth nodes,
response
toward
or are
away
from stimulus.
Stems—contain
where
leaves
attached,
and internodes, or regions
— tropism
is called
positive
plantto
grows
toward
stimulus
if plant
between
the nodes.
Where
leaves if
attach
the nodes,
small
buds, or
or negative
undeveloped
grows
away
plant tissue, can be found.
Phototropism
— growth
of plant
toward
light (showing
positive phototropism)
Leaves — capture
the sun’s
energy
and carry
out the food-making
process of
photosynthesis.
Gravitropism — plant growth in response to gravity. Roots show positive
gravitropism and stems show negative gravitropism
To collect sunlight, most leaves have thin, flattened sections called blades. The blade
is attached to the stem by a thin stalk called a petiole.
Thigmotropism — plants response to touch. Stems of many vines show positive
thigmotropism.
A waxy cuticle and stomata, or openings in underside of leaf which allow CO2 and
Hydrotropism — plants growth in response to water.
O2 exchange, help reduce water loss or transpiration from the plants leaves.
Plants are able to respond to touch, light and gravity because they produce hormones. A
hormone is a chemical that affects how the plant grows and develops.
Photoperiodism — plant’s response to seasonal changes in length of night and day.
Dormancy — period when an organisms growth or activity stops
Angiosperms (flowering plants) are classified based on the length of their life cycles:
Annuals
Biennials
Perennials
Have a life cycle within
one growing season.
Complete their life cycle in
two years.
Plants that live for more than
two years
Ex. Marigolds, petunias,
cucumbers.
Ex. celery, parsley,
foxglove
Ex. peonies, maple trees