1. Seeds and Fruits
Types & Dispersal

2. Seeds and Fruit
Fruits are formed by seed plants to aid in dispersing seeds
A seed contains the developing plant embryo in a protective coat (testa)
Seeds form from ovules fertilized in the ovary
Ovaries with seeds ripen into dry or fleshy fruits

3. Parts of a Seed External seed coat or testa Developing plant embryo
Stored food called endosperm
Seeds may be in one part (monocot) or two parts (dicots)
DICOT
MONOCOT

4. Parts of a Seed

5. Gymnosperm Seed
A single fertilization produces the diploid (2n) embryo
The food source is the haploid megagametophyte

6. Dicot vs. monocot seed Dicot has two cotyledons (like bean)
Monocot has one cotyledon which absorbs the endosperm tissue during germination (corn)

7. Fruit
In flowering plants – Fruit is a mature, ripened ovary that contains the seeds
Pericarp – the ovary wall
ovary
Fruit types
A. Simple
B. Aggregate
C. Multiple

8. A. Simple fruit
A. Simple fruit – develops from a ripened ovary of a single flower.
Simple fruits can be either fleshy or dry when mature

9. Simple fleshy fruit
1. Berry – entire fruit wall is soft and fleshy at maturity. Inside is slimy.
For example, grapes, tomato, etc.

10. 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

11. Simple dry fruit: Legumes
Legumes are dry at maturity and split open
Examples: pea pods, bean pods, peanut

12. 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 wheat)
Nuts: single-ovary wall and seed coat remain separate, ovary wall is very hard (acorns)

13. C. Multiple fruit
Multiple fruit develops from ovaries of several flowers borne/fused together on the same stalk
For example: Pineapple

14. 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 competition 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. Wind dispersal
C. Water dispersal
D. Animal dispersal

15. A. Self dispersal
Plants disperse their seeds by forceful ejection – explosive fruits!
Witch hazel, squirting cucumber (jet propulsion)

16. Self dispersal The peanut plant sows (buries) its own seeds!
Geocarpic: carpel grows inside the earth (soil)

17. 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

18. C. 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: for example coconuts.

19. D. Animal 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

20. 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)

21. A few plant images you should know!