Plants

Structure and Reproduction

Characteristics of Plants Autotrophic Multicellular Eukaryotic Cell wall made of cellulose Organelles including chloroplasts Large, central vacuole

Plant Tissues Dermal: outermost layer

on leaves and stems; covered with a waxy layer called the cuticle

Vascular: used for transport

Ground: photosynthetic cells, support cells, and all other cells that are not dermal or vascular

Plant Structures

1. Roots: Usually the part of the plant that grows below

the surface of the soil Absorb water and minerals Anchor the plant Can store food 2 types—taproot and fibrous root

2. Stems: Support leaves and flowers Transport water and nutrients within the plant

Can function to store food (ex: potato is an underground stem)

Node: place where leaves attach to stems3. Leaves:

Organs where photosynthesis occurs Has an outer dermal tissue with stomata The stoma is surrounded by guard cells

that allow carbon dioxide to enter and oxygen & water to leave

Has an inner ground tissue, made of parenchymal cells, that has vascular tissue (the vein) within it

Common features of leaves include: Blade: flat, broad section of the leaf Petiole: short stalk that connects the blade to the stem Veins: carry water, minerals and sugar

Can be simple or compound

Compound leaves can be pinnate or palmate

4. Flowers: Modified stems with specialized leaves and other

structures for reproduction Has 3 types of parts:

Male Reproductive Parts Called the stamen Made up of the anther (produces pollen) and the

filament (supports the anther)

Female Reproductive Parts Called the pistil Made up of the stigma (the pollen lands

here), the style (connects the stigma and the ovary) and the ovary (makes ovules)

Sterile Parts Petals: brightly colored parts of the

flower Sepals: green, leaf-like structures that

support the flower

Asexual Reproduction It produces clones, genetically identical

offspring In a stable environment with abundant

resources, asexual reproduction is faster than sexual reproduction and produces offspring that are well adapted to the existing environment

Sexual Reproduction Results in seed formation The seed is a plant embryo with its stored food Advantages of seeds:

Can be spread out over great distances Seeds can stay dormant for long periods of time

For flowering plants, sexual reproduction begins with the process of pollination

Pollination Process of transporting pollen (male gamete)

from the male flower parts to the female parts Pollen is transported by wind, water, insects,

or other organisms

Fertilization Pollen lands on the stigma Pollen tube grows down through

the style to the ovary Sperm nuclei are carried along the

pollen tube Pollen tube enters the ovule Sperm nucleus fuses with the egg

and forms a zygote A 2nd sperm nucleus fertilizes 2

polar nuclei to form a food-storing tissue called endosperm

Fertilization (cont.) Zygote develops into an embryo Ovule becomes a seed The rest of the ovary becomes a fruit, which will

house and protect the seeds and help disperse the seeds to new locations

Plant Classification Plants are divided into groups based on

three key features: The presence of vascular tissue The presence of seeds The presence of flowers

The groups are: Nonvascular plants--mosses Vascular seedless plants--ferns Vascular seed plants

Gymnosperms (seeds in cones)--pines Angiosperms (seeds in flowers)

Angiosperm Classification Angiosperms can be classified in several ways One classification system, based on the

physical characteristics of the plant, is to divide them into the monocots and the dicots

Another classification system is based on life span

Monocot Monocot:

Have a single cotyledon (leaves in the embryo)

Veins are parallel Vascular bundles are scattered

throughout the stem Have fibrous roots Floral parts in multiples of 3

Dicot Dicot:

Have two cotyledons Veins are branched Vascular bundles are arranged

in a ring in the stem Have taproots Floral parts in multiples of 4 or

5

Life Span Annual: plants grow,

mature, flower, produce seeds and die in one growing season

Biennial: complete their life cycles in two years

Perennial: live for more than two years FoxgloveVerbena

Sapphire flower

Petunia

Lupin Sunstar