Plants: Adaptations of Plants

I. ESTABLISHMENT OF PLANTS ON LAND

• 1. Dominant group of organisms on land due do adaptations– A. photosynthetic– B. parasitic

• 2. Evolution– A. from multicellular green algae found in water– B. multicellularity helped plants develop to do

three main things:• 1. abosorb nutrients• 2. prevent their bodies from drying out• 3. reproduce without water

• 3. Absorbing Nutrients– A. take nutrients from water around them• 1. Land plants = roots• 2. Early plants = no roots, fungi helped get nutrients

from Earth’s rocky surface in a mutualistic relationship called micorrhizae

• 4. Preventing Water Loss– A. First plants = life by water source, drying out

not an issue– B. Plants move to dryer habitat= cuticle or waxy

layer that covers non-woody above ground parts of plants and does not let oxygen or carbon dioxide pass through

– C. Gas exchange for photosynthesis= stomata- pores that permit plants to exchange oxygen and carbon dioxide

– D. Guard cells surround the stomata to controll amount of gas exchange

• 5. Reproduction on Land– A. Early plants and algae= rely on water for sperm

to swim to fertilize egg– B. Pollen- allow sperm to be carried by wind or

animals to fertilize egg rather than by water, also keeps sperm from drying out by enclosing it

II. VASCULAR TISSUE, SEEDS AND FLOWERS

• A. Many features help plants success in adapting to land: roots, stems and leaves, and conducting tissues

• B. Advantages of Conducting Tissues– 1. First plants = small, transport of materials by

osmosis and diffusion– 2. Specialized tissues and cells now transport materials– 3. Vascular tissue- specialized cells that transport

water and other materials within a plant tht make up a vascular system

– 4. There are two types of plants: non-vascular which lack a vascular system and vascular which have a vascular system

• C. Seed Structure– 1. structure that contains the embryo of the plant– 2. embryo- early stage in development of plants

and animals– 3. seed plants- vascular plants that produce seeds

and first appeared 380 million years ago

• D. Advantages of Seeds– 1. protection- seed coat that protects the embryo

from drying out and from injury and disease– 2. nourishment- supply embryo with stored

nutrients as it starts growing– 3. plant dispersal- structures that help with wind,

water, or animal dispersion that prevents competition for light, nutrients, water, and living space between parents and offspring

– 4. delayed growth- seeds will not sprout unless conditions are favorable, thus increasing their chances of survival

• E. Advantages of Flowers– 1. Flower- reproductive structure that produces

pollen and seeds– 2. enable cross pollinations from one flowers

pollen to another flowers egg, increasing genetic diversity

– 3. attract animals and use them for dispersal

III. PLANT LIFE CYCLES

• A. Haploid plants that make gametes alternate with diploid plants that make spores– 1. Gametophytes- make gametes– 2. Sporophytes- make spores

• B. Alternation of generations– 1. Gametophytes and sporophytes look very different– 2. Non-vascular plants have a dominant gametophyte

generation while vascular plants have a dominant sporophyte generation

– 3. The size of the gametophyte and sporophyte generation is also a difference between vascular and non-vascular plants

• C. The Vascular Plant Sporophyte• The following features characterize the sporophytes

of most vascular plants– 1. Vascular System- made up of tubes of pipes that

transport water and nutrients in the plant• A. Phloem- soft-walled cells that transport organic nutrients • B. Xylem- hard – walled cells that transport water and minerals

– 2. Distinct Body Form• A. Shoot- th part of the plant’s body that grows upward• B. Root- the part of a the plant’s body that grows downward• C. Meristem- zones of actively dividing plant cells and produce

plant growth• D. Roots, Stems and Leaves- better adapted plants for life on

land

Shoot System

Root SystemRoot Meristem

Shoot Meristem