Learning Target: Seed Dispersal

I Can… Describe different ways that seeds can be dispersed and compare/contrast the advantages/disadvantages of the different methods

I Will… • Define seed dispersal• List methods of seed dispersal including

examples of plants for each method• Discuss advantages/disadvantages of each

method

Seed Dispersal

Dispersal (the process or result of the spreading of organisms from one place to another) is important because:

1.It spreads the progeny (offspring) in order to colonize new environments

2.Reduces competition for resources with parents

3.Reduces chances of predators destroying all of the plant’s yearly seed production

Self Dispersal• Plants disperse their seeds by forceful

ejection• Explosive fruits• Witch Hazel• Squirting Cucumber

http://youtu.be/q5g7EV2fgJw

Self Dispersal

The peanut plant sows (buries) it own seeds

Wind Dispersal• Fruit and seeds may have special

devices for wind dispersal• Plumes catch wind currents• Dandelion

• Trees take advantage of their great heights for wind dispersal• Fruits with wings are used to slow

descent to land• Maple • Ash

Water Dispersal• Fruits and/or seeds use flotation devices to travel by water ( in rivers, oceans, etc…)• Fruit may

have air spaces and corky floats

• Palm Coconuts

Water DispersalLotus Flower

Animal Dispersal

Many plants depend on animals for seed dispersal• Offers nutritional reward• Animals learn to recognize ripened

fruit colors• Fleshy fruit eaten and seeds

dispersed in feces

Animal Dispersal• Some dry fruit attach and cling to

animal’s fur (e.g. Beggar’s ticks)• Some have Velcro-like hooks that

cling to fur (Burdock, Cockleburs)• Others have sticky substances that

adhere to host (e.g. Mistletoe)

Methods of Seed Dispersal

http://youtu.be/6loGKPKDqCw

http://youtu.be/rhp5k5ptSx0?t=23s

How Plants Disperse SeedsTime: 3 mins 30 secs

Seed DispersalTime: 4 mins 17 secs

Seed Dispersal: Things that make you THINK

• What carries the dandelion seed for miles?• What feature of trees gives them a

particular advantage when dispersing seeds by air?

• How does the squirting cucumber disperse its seeds? • What is the advantage of this?

• Although plants use wind and water, what do most plants use as carriers for their seeds?

• Blackberries on a tree do not ripen simultaneously, WHY?