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Plants
Classifying Plants:
2 Main Groups of Plants:
A. Nonvascular: have no vessels,
no roots, no stems or leaves.
Examples: Mosses & Liverworts
Bryophytes
• Depend on water for reproduction
• Lack vascular tissue (specialized
tissues that conduct water and
nutrients)
• Can only draw up water by osmosis
• Can only grow a few cm above
ground
Groups of Bryophytes
• Mosses
• Liverworts
• Hornworts
Mosses
• Phylum Bryophyta
• Grow in areas w/ water
Moss
Liverworts
• Phylum Hepaticophyta
• Produce structures that look like tiny green
umbrellas that produce egg & sperm
• B. Vascular: have vessels to transport
food and water. They have roots, stems
and leaves. Example: Grass, corn, trees,
flowers, bushes
• Two Types of tissue:
• 1. Xylem: transports water
2. Phloem: transports food & nutrients
Two Groups of Vascular Plants
A. Gymnosperms
• "naked seeds"
• cone bearing plants (seeds grow on
cones)
• needle like leaves
• usually stay green year round
• wind pollinated
• Examples: pine trees & evergreens
B. Angiosperms
• flowering plants
• seeds are enclosed in a fruit
• most are pollinated by birds & bees
• have finite growing seasons
• Examples: grasses, tulips, oaks, dandelions
• Divided into two main groups: Monocots &
Dicots
Angiosperms
Two Groups of Angiosperms
A. Monocots
• Angiosperms have have 1 seed leaf
(cotyledon)
• parallel veins on leaves
• 3 part symmetry for flowers
• fibrous roots
• Example: lilies, onions, corn, grasses,
wheat
•
• A: vascular bundle (scattered thru stem)
B: ground tissue: storage, support
B. Dicots
• Angiosperms that have 2 seed leaves
(cotyledons)
• net veins on leaves
• flowers have 4-5 parts
• taproots
• Examples: trees and ornamental flowers
•
• A: epidermis
B: vascular bundle (arranged in a ring)
C. ground tissue (pith)
D. cortex
Parts of the Plant
A. Roots
• water and minerals are absorbed (taproots vs
fibrous roots)
• also used to anchor the plant
• movement of water up to leaves is influenced by
TRANSPIRATION
• Two types of roots:
– Taproot-1 primary root long and thick while
secondary roots are small
– Fibrous Root-no single root grows larger than the
rest
B. Stems
• Support plant
• transport water through xylem
• transport nutrients through phloem
• a celery stalk soaked in food coloring will
absorb the food coloring, you can see the
xylem
• Two types of stems: herbacious and
woody
C. Leaves
• Photosynthetic organ of the plant, used to convert
sunlight into food
• Structures:
Cuticle: waxy covering, prevents water loss
Xylem: vascular tissue, transports water
Phloem: vascular tissue, transports nutrients (phood)
Stomata (stoma): pores used for gas exchange
Guard cells: open and close stomata
Mesophyll: middle tissue, cells have chloroplasts used
for photosynthesis, mesophyll consists of the spongy
and palisade layers
Epidermis: layer of cells just under the cuticle
Vein: a structure composed of xylem and phloem, veins
run from the tips of the roots to the edges of leaves
D. Flower
• Reproductive organ of the plant
• Flowers are usually both male and female
• The male part of the flower is the STAMEN
• The female part of the flower is the PISTIL
• See your coloring sheet for more detail on
flower anatomy
Plant Reproduction
• Pollen is produced by the stamen.
• Pollen moves away from the plant via the wind or other
pollinators (birds & bees)
• The pollen lands on the pistil of another plant and
fertilizes the eggs within the ovary
• The flower petals fall off, the ovary develops into a
FRUIT that encloses the seeds
• Fruits are dispersed in a variety of ways (wind, animals)
• Fruits are not always edible, anything with a seed inside
can be considered a fruit (helicopters, acorns,
dandelions)
Plant Reproduction
• Alternation of generations life
cycle
• Diploid (2n) sporophyte stage
• Haploid (1n) gametophyte stage
• Produce multicellular embryo
protected inside multicellular
haploid (gametophyte egg sac)
tissue
Plant Reproduction
• Diploid (2n) sporophyte stage
produces haploid spores by
meiosis
• Haploid spores undergo mitosis to
produce gametophyte stage
• Gametophyte makes gametes
(eggs and sperm) by meiosis
• Zygote (2n) produces the new
sporophyte
Alternation of Generations
Gametophyte
2n Sporophyte
2n gametophyte
1n pollen
2n seed with
plant embryo
Sporophyte
Ovary with
1n ovules
(eggs)
Asexual Reproduction in Plants
• Many plants can clone themselves, a process
called VEGETATIVE PROPAGATION
• strawberry plants and other vine like plants send
out runners, which grow into new plants
• some plant clippings will grow into new plants
• a Potato will grow into a new plant
How Plants Grow
• Germination occurs when a seed sprouts
(usually caused by changes of
temperature and moisture)
• Monocots have 1 seed leaf (cotyledon),
Dicots have 2 seed leaves
• Perennials - live serval years, and reproduce many times, woody
plants are perennials
• Annuals - a plant that completes its life cycle in one growing season
(grows, flowers, reproduces and then dies)
• Biennials - takes two growing seasons to complete, it reproduces in
the second growing season
• Plants grow only at their tips in regions called MERISTEMS
• PRIMARY GROWTH makes a plant taller at roots and stems
• SECONDARY GROWTH makes a plant wider, or adds woody tissue
• Tree Rings tell the age of a tree, each ring represents a growing
season. The photo shows a tree who has been through four growing
seasons. The lighter thinner rings are winter periods.
• VASCULAR CAMBIUM: area of the tree that makes more xylem and
phloem and forms the annual rings
Plant Hormones
• Chemical substances that control a plant’s
pattern of growth and development and
the plant’s response to environmental
conditions
• Auxins-simulate cell elongation
• Cytokinins-simulate cell division
• Gibberellins-increase in size
• Ethylene-causes fruits to ripen
• Phototrophism-Response to light
• Gravitrophism-Response to gravity
• Thigmotropism-Response to touch