Lec14 seeds and fruit

• Simple fruits can be either fleshy or dry when mature • Simple fleshy fruit... Berry – entire fruit wall is soft and fleshy at maturity.. Pomes: most of the fleshy part of pomes deve

Lecture 14: Seeds and Fruit

• Seeds

• Fruits

• Fruit types

• Seed dispersal

• Video: seed dispersal

• Real fruit samples

• The seed contains a well-formed

multicellular young plant embryo (germ)

• Embryo is _ (2n)

• It will become a whole plant

Nutritive tissue

• Seed contains a food supply

• Stored food contains enough energy for the

embryo to grow through the soil, when

seedling is unable to photosynthesize

• Food source can be the _, which is (_n) – as a result of double fertilization

Seed coat

• A thick protective coat – outer layer of the seed

• Formed from the _

Seed coat

Flowering plant seed

• In angiosperms (flowering plants) there is

Dicot vs monocot seed

• Dicot has two

cotyledons (like bean)

• In flowering plants – Fruit is a mature,

ripened o _ that contains the seeds

• Pericarp – the ovary wall ovary

Fruit types

• A Simple

• B Aggregate

• C Multiple

A Simple fruit

• A Simple fruit – develops from a

ovary of a single flower

• Simple fruits can be either fleshy or dry when mature

• Simple fleshy fruit

Simple fleshy fruit

• 1 Berry – entire fruit wall is soft

and fleshy at maturity Inside is

slimy

• For example, grapes, tomato, etc

• 2 _ is a berry

with tough, leathery rind (peel)

• Examples: oranges, lemons,

other citrus

Simple fleshy fruit: drupe

• 3 _ type – outer part of fruit wall is

soft and fleshy, inner part is hard and stony

• For example:

Simple fleshy fruit: pepo

• 4 – also a fleshy fruit with a tougher

outer rind

• All member of the squash family: pumpkin,

melons, cucumbers

Simple fleshy fruit: pome

• 5 Pomes: most of the fleshy part of pomes

develops from the enlarged base of the perianth (corolla and calyx) that has fused with the ovary wall

• Pomes include _

Simple dry fruit: capsule

• Simple dry fruits are dry (not fleshy) at

maturity Simple dry fruits that open at maturity

include: capsules and legumes

• Capsule – fruit is dry at maturity and splits open

along several seams

• Example: Cotton

Simple dry fruit: Legumes

• Legumes are dry at maturity and split open

along _ seams

• Examples: pea pods, bean pods, peanut

Simple dry fruits

• Simple dry fruits that do NOT open at maturity include

• Caryopsis: seed coat is fused

to the ovary wall (cereal grains

like )

• Nuts: single-ovary wall and

seed coat remain separate,

ovary wall is very hard

(acorns)

B _

• fruit develops from one flower

with many separate pistils/carpels, all ripening simultaneously

• Examples: strawberry, raspberries, blackberries

C Multiple fruit

• Multiple fruit develops from ovaries of

several flowers borne/fused together on the same stalk

• For example:

What is the purpose of the fruit?

• The main function of the fruit is to disperse the seeds

• Dispersal is important because

• 1 It spreads the progeny in order to colonize new

environments

• 2 Reduces for resources with parents

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

• Four types of seed dispersal:

• A Self dispersal

• B dispersal

• C Water dispersal

• D _ dispersal

Self dispersal

• The peanut plant sows

(buries) its own seeds!

• Geocarpic: carpel grows

inside the earth (soil)

B 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 the descent to land: maple, ash fruit

C _ Dispersal

• Fruits and/or seeds use flotation devices to

travel by water (in rivers, oceans, etc.)

• Fruit may have air spaces and corky floats: for example

D Animal dispersal

• Plants have _ with animals to accomplish seed dispersal

• Many plants depend on animals for seed

dispersal; they may offer a nutritional reward

• Animals learn to recognize ripened fruit colors

• Fleshy fruits eaten and dispersed

with feces

Animal dispersal

• Some dry fruit attach and cling to animals

(they hitchhike on the animals)

• Some have Velcro-like hooks that cling to

animal fur (burdock, cockleburs)

• Others have sticky substances that stick to host (mistletoe)

Video on seed dispersal

• Watch the video, take notes, answer these questions:

• What carries the dandelion seeds for miles?

• What feature of trees gives them a particular advantage when dispersing seeds by air?

• How does the squirting cucumber disperse its seeds?

• 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?

• What plant do elephants help to disperse? How do they

do it? What percentage of these seeds germinate in