Introduction to Plants Chapter 12

12.1 What is a Plant? Trees, grass, ferns, mosses, cactuses, water lilies Can live on land, in or near water Many celled; made up of eukaryotic (have a nucleus) cells Photosynthesize (producer = make food like glucose & oxygen from carbon dioxide & water) Have chlorophyll (green pigment that captures energy from sunlight)

What is a Plant? Chlorophyll found in chloroplasts Have cuticle or waxy layer that coats plant leaves & stems to keep them from drying out Cell walls to provide protection & support (help them stay upright) Cell wall made up of cellulose (organic compound w/long chains of sugar molecules)

What is a Plant? Roots to hold them in the ground Roots & stems carry water, nutrients, remove waste, & provide support Reproduction – 2 stages 1. sporophyte stage = plants make spores 2. gametophyte stage = new plant grows from a spore (eggs & sperm produced & join)

Plant Classification Nonvascular Moss, liverwort No vascular tissue (xylem & phloem) to move materials Diffusion moves material from one part of plant to another Can absorb water through their cell walls

Plant Classification Vascular Plants that have vascular tissue (known as xylem & phloem) Vascular Tissue = long tube-like cells that carry water & nutrients throughout the plant Divided into 3 groups -Seedless like ferns, horsetail, & club moss -Nonflowering Seed plants called gymnosperms (like pine tree) -Flowering Seed plants called angiosperms (like apple tree)

Origin of Plants Green algae & plants share common ancestor Lots of similarities like chlorophyll, cell walls, photosynthesize, store energy as starch, both have 2 stage life cycle

12.3 Seed Plants Characteristics of Seed Plants: Produce seeds Seeds nourish & protect young sporophytes (plants) Gametophytes form within reproductive structures of sporophyte Sperm need water to swim to the egg Sperm form inside pollen

Structure of Seeds Seed coat = surrounds & protects young plant Cotyledons = stored food Sporophyte = young plant made up of plumule (future leaves) & radicle (future root)

Gymnosperms Vascular plants Produce seeds on scales of female cones Means naked seed (seeds not surrounded by a fruit) No flowers or fruit Leaves mostly needlelike or scalelike Evergreen plants that keep leaves year round

Gymnosperms Most familiar is conifers (or cone-bearing): pines, firs, spruces, cedars, junipers, ginkgos Wood used for building, paper. Contain resin (sticky fluid made by tree) which used in paint, soap, ink, some medicines

Gymnosperms Life cycle = male gametophyte found in pollen (pollen contain sperm) & female gametophyte make eggs; fertilized egg develops into young sporophyte Pollination – transfer of pollen from male cones to female cones usually by wind (both male & female cones can be on same tree)

Angiosperms Vascular plant Fruit surrounds & protects seeds You eat part of angiosperm Produce flowers AND fruit

Angiosperms Flowers help angiosperms reproduce (insects carry pollen from flower to flower) Some seeds carried by wind or eaten by animal then disposed of in feces Uses: crops like wheat, rice, & corn, food for animals, produce tons of oxygen, clothing, rubber, oils, perfumes, building materials Two types: monocot & dicot

Monocots Mono means one Have one seed leaf or cotyledon inside their seeds Flower parts in threes Vascular bundles (xylem & phloem) are scattered randomly Leaves have parallel veins Examples: corn, rice, wheat, oats

Dicots Di means two Have two seed leaves or cotyledons inside their seeds Flower parts in fours or fives Vascular bundles (xylem & phloem) form a ring Leaves have netlike or branching veins Examples: maples, lettuce, beans, oranges, watermelons

Structure of Seed Plants 12.4

Vascular Tissue Found in root & shoot systems Made up of xylem, phloem, & cambium Xylem transport water & minerals up from roots throughout plant Phloem transport food from leaves & stems to other parts of the plant Cambium found between xylem & phloem and makes NEW xylem & phloem cells

Roots Supply plants w/water & minerals by absorbing them from soil Hold plants in soil Store food made during photosynthesis Eat some roots (ex. carrots, beets)

Roots Roots have an epidermis (covers outer surface), root hairs (increase surface area), root cap (protects root tip) Roots grow longer at their tips

Roots Kinds of root systems: Fibrous (several roots that spread out from base of plant’s stem, roots same size - monocots) Taproot (large main root w/smaller roots branching off, grows downward – dicots & conifers are examples)

Stems Tree trunks are really stems Supports plant body like leaves & flowers Carries water & minerals (xylem) from roots to leaves and food (phloem) back down to roots Some stems can store food or water

Stem

Stems Stems either herbaceous (soft, thin, flexible stems) or woody ( hard, rigid stems) Flower & crops are herbaceous while trees & shrubs are woody

Stems Growth ring = ring of dark cells surrounded by ring of light cells (equals one growing season)

Leaves Vary in size but main job is to make food for the plant (photosynthesis) Chloroplasts capture energy from sunlight to make food (glucose) Cuticle (waxy layer on stems & leaves which keeps plants from drying out or wilting) Epidermis (upper & lower) single layer of cells

Leaves Stomata (tiny openings in epidermis) allow carbon dioxide to enter leaf & oxygen to leave Stomata surrounded by guard cells which open & close stomata Palisade layer (look like long pillars) contain chloroplasts & most of food made here Spongy layer (circular) loosely arranged cells, many air spaces which contain xylem & phloem.

Flowers Flowers are reproductive organs Shape, size & color of flowers tells lots about a plant’s life Brightly colored & fragrant flowers rely on animals for pollination Plants w/o bright flowers rely on wind for pollination

Flowers Flower Parts: Colored parts are the petals (broad, flat, leaflike) Sepals modified leaves outside the petals; protect the bud

Flowers Male Parts: Stamen is the male reproductive organ Made up of: 1. a filament (long stalk) 2. anther (at the top of the stalk) pollen stored, sperm made here

Flowers Flower Parts: Pistil is the female reproductive organ Made up of: 1. a stigma (sticky part on top to catch pollen) 2. style (long, slender tube) 3. ovary (rounded base of the pistil) ovules formed, eggs made here

Flower Anatomy