Plants

Structure and FunctionAdaptations

The Plant Cell- review• Are plants autotrophic or heterotrophic?

– Autotrophic (remember, plants are producers and they make their own food via photosynthesis)

• Are plants prokaryotic or eukaryotic?– Eukaryotic (remember, eukaryotes have nuclei just like

we do and YOU are EUkaryotes)

• Are plants multicellular or unicellular?– Multicellular!

• Plant cell walls are made of….– Cellulose

The Plant Cell:Label!

Nonvascular vs. Vascular

Nonvascular plants do not have a system for transporting water and other nutrients within their body– Nonvascular plants are small and lack vascular tissue (roots, stems and

leaves).

– Mosses, liverworts, and hornworts are nonvascular plants.

Nonvascular vs. VascularVascular plants are plants that contain structures with vascular tissue

(roots, stems and leaves)– Seedless plants– Seed plants

• Gymnosperms and Angiosperms

• Vascular plants are composed of:– Tissue– Roots– Leaves– Stems– Each plant part – tissue, root, stem, leaf - has a specific

role in keeping the plant alive through photosynthesis

Vascular PlantsSeedless Vascular Plants:

– Seedless vascular plants produce spores with thickened walls that prevent them from drying out.

– Examples: Ferns, club mosses, horsetails, and whisk ferns are seedless vascular plants.

Reproduce with spores

- diagram shows spores growing in clusters called sori on the back of the fern

http://en.wikipedia.org/wiki/Image:Lycopodium_plant.jpg

Structures of Vascular PlantsSeed- adaptation to terrestrial life composed of a plant embryo, stores food and contains a protective coat

Cone- reproductive structure of gymnosperms; contains pollen in males and ovules in females

Ovulate cone- from a pinetree (female)

Staminate cone- from a pinetree (male)

Flower- reproductive structure of angisperms composed of 4 sets of modified leaves

Fruit- mature ovary of a flower that protects dormant seeds and aids in their dispersal

Cotyledons – nonphotosynthetic leaves of an immature plant;

provide source of nutrients until plant can produce

its own food

Vascular Plants

• Vascular Plants that produce seeds:– Gymnosperms

• Produce cones– Conifers, cycads, ginkgoes, and gnetophytes

– Angiosperms• Fruits or flowers

– The angiosperms are classified as either monocots or dicots.

AngiospermsMonocot vs. Dicot• Monocots:

– One cotyledon– Veins parallel– Vascular bundles in complex arrangement– Fibrous root system– Floral parts in multiples of three– Ex. Iridaceae (irises), Liliaceae(lilies) and Poaceae (grass).

• Dicots:– Two cotyledon– Veins netlike– Vascular bundles arranged in ring– Taproot usually present– Floral parts in four or five– Ex. Asteraceae (composite), Brassicaceae (mustard),

Fabaceae (legume), and Rosaceae (rose),

Tissues, Roots, Leaves, StemsTissueA vascular plant’s body contains three kinds of tissues

—dermal tissue, ground tissue, and vascular tissue.

– 1.Dermal Tissue Dermal tissue covers a plant. A thin layer of epidermis covers nonwoody parts. Several layers of cork cover woody parts.

– 2.Ground Tissue Ground tissue is specialized for photosynthesis in leaves and for storage and support in stems and roots.

– 3.Vascular Tissues Vascular tissue conducts water, minerals, and organic compounds throughout the plant.

• Xylem (carries reactants) vs. phloem (carries products)

Vascular – refers to an internal system of tubes or vessels to transport materials throughout the plant

- xylem – transports water and minerals up from the roots to the shoots

- phloem – transports sugar (food) down from the leaves to the rest of the plant

Translocation Organic compounds are pushed through the phloem from a source to a sink in a process called translocation.

Transpiration Transpiration, the loss of water from a plant’s leaves, creates a pull that draws water up through xylem from roots to leaves.

RootsFunction- absorption, storage and anchorage• Roots have a central core of vascular tissue that is

surrounded by ground tissue and epidermal tissue. • Root hairs on root tips increase the surface area which

increases absorption• Remember that Nitrogen Fixation happens in the

roots!

(Nitrogen fixation is when nitrogen in theatmosphere is converted by bacteria into nitrogen compounds like ammonia, nitrates and nitrites)

StemsFunction: support and transfer• Contain the Xylem and Phloem• Help define plant types (shrubs, vines, trees,

etc)

Leaves• Site of photosynthesis

• composed of blade, veins, petiole

• simple or compound

Simple leaf shapes

Entire leaf

Palmate (heart shaped)

Palmately lobed

Pinnately lobed

Compound leaf shapes

Singly compound leaf

Palmately compound leaf

Doubly compound leaf

• There are different layers of leaves • epidermis – adaptation for terrestrial life- covering

of leaf

• waxy cuticle - coats upper and lower epidermis

• stomata – site of transpiration

• Guard cells- control water loss by closing a plant’s stomata when water is scarce

See pg. 559 – Yes, you need to know the layers of leaves

Plant Adaptations• Absorbing Nutrients

• To survive on land, plants evolved the ability to absorb mineral nutrients from the soil.

• Preventing Water Loss • To survive on land, plants

evolved a waxy outer covering called a cuticle, and stomata and guard cells for gas exchange, to prevent their bodies from drying out.

• Reproducing on Land • To survive on land, plants use

pollen to reproduce without water and transmit male gametes.

Vascular Plant Adaptations• Advantages of Conducting

Tissue • Vascular plants have a system

of well-developed tissues that transport water within a plant.

• Advantages of Seeds • Seeds protect and nourish a

plant’s embryo, disperse the offspring, and delay the growth of the embryo until conditions are favorable.

• Advantages of Flowers • Flowers make reproduction

more efficient by promoting pollination.

Plants in our Lives• Fruits and Vegetables

– All types of plant parts—roots, stems, leaves, flowers, fruits, and seeds—provide food for humans.

• Root Crops – Root crops, such as potatoes, grow underground.

• Legumes – Legumes, such as peas, produce protein-rich seeds in long pods.

• Wheat – For more than one-third of the world’s population, wheat is the

primary source of food.• Corn

– Corn is the most widely cultivated crop in the United States.• Rice

– For more than half of the people in the world, rice is the main part of every meal.

Plants in Our Lives

• Wood – Wood is a source of wood pulp used for making paper, lumber used for

building materials, and fuel.• Medicines

– Many important medicines are currently made from plants or were originally derived from plants.

• Fibers – Plant fibers are used to make paper, cloth, and rope. The most

important sources of plant fibers are wood and cotton.

Fruit or Veggie?

• A fruit is the ripened ovary and contains seeds.

• Therefore, tomatoes, peppers, squash, olives, and cucumbers are FRUITS, not vegetables.

Nonvascular Plants(Bryophytes)

- spores

Vascular Plants (Tracheophytes)

Seed PlantsSeedless Plants- spores

Flowering Plants(Angiosperm)

260,000 species

Conifers(Gymnosperm)

600 species

Monocot60,000 species

Most grains

Dicot200,000 species

Most flowering plants

MossesLiverwortsHornworts

26,000 speciesFerns

12,000 species