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 water2. 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: epidermisB: 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 lossXylem: vascular tissue, transports waterPhloem: vascular tissue, transports nutrients (phood)Stomata (stoma): pores used for gas exchangeGuard cells: open and close stomataMesophyll: middle tissue, cells have chloroplasts used for photosynthesis, mesophyll consists of the spongy and palisade layersEpidermis: layer of cells just under the cuticleVein: a structure composed of xylem and phloem, veins run from the tips of the roots to the edges of leaves

http://www.enchantedlearning.com/subjects/plants/leaf/label/margins/

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

http://www.enchantedlearning.com/subjects/plants/printouts/floweranatomy.shtml

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)

http://www.enchantedlearning.com/subjects/plants/printouts.shtml

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

2n 2n SporophyteSporophyte

2n 2n gametophytegametophyte

1n 1n pollenpollen

Ovary with Ovary with 1n ovules 1n ovules (eggs)(eggs)

2n seed 2n seed with plant with plant embryoembryo

SporophySporophytete

GametophyGametophytete

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

http://www.enchantedlearning.com/subjects/plants/printouts/bulbanatomy.shtml

• 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