Fruit and Seed Dispersal: 'What do we do with the kids?'

        I. Seeds
            A. In general, a seed is a mature ovule consisting of a (2n) zygote which develops into an embryo, nutritive tissue, and a seed coat
            B. Gymnosperm seeds
                    1. The single fertilization event produces a 2n embryo.
                    2. 1n nutritive tissue
                    3. a seed coat
            C. Angiosperm seeds
                    1. Double fertilization produces:
                        a) a 2n embryo. Can be either a monocot or dicot.
                        b) The 3n endosperm (storage tissue rich is starch that provides enough energy for the embryo during the germination of the seed).
                    2. a seed coat
       II. Fruits and seeds are adapted for dispersal
            A. Why dispersal is important
                    1. spreads out progeny to new environments
                    2. reduces competition for resources with parent plant
            B. Types of fruit and seed dispersal
                    1. self dispersal: explosive fruit
                    2. wind dispersal: plumes to catch the wind.  Wings to slow descent in the wind
                    3. water dispersal: floatation
                    4. animal dispersal: hitchhiking on animal fur.  Reward based types have fleshy fruit around the seed.
        III. Fruits
            A. A fruit is a mature ripened ovary.  It protects the seeds and aids in seed dispersal.
            B. The Parts of a fruit:
                    1. Pericarp: the ovary wall consisting of the exocarp (outer ovary wall), mesocarp (middle ovary wall), and endocarp (inner ovary wall).  All surround the seed.
            C. Types of fruits
                    1. Simple fruit: develops from a single ovary of a single flower; may be either fleshy or dry when mature
                        a) Simple fleshy fruits
                            (1) Berry - entire outer and middle ovary walls are soft and fleshy; inner wall is fleshy and slimy (tomato).
                            (2) Drupe - outer ovary wall is soft and fleshy, inner part is hard and stony pit (peach, cherry)
                            (3) Pome - edible outer fruit wall comes from receptacle tissue, not ovary tissue (apple, pear)
                        b) Simple dry fruits that split open at maturity to release seeds
                            (1) Follicle - splits open along one seam (milkweed)
                            (2) Legume - splits open along two seams (peas, beans)
                            (3) Capsule - splits open along several seams or seeds released through pores (cotton, lily, iris)
                        c) Simple dry fruits that DO NOT split open at maturity to release seeds
                            (1) Caryopsis - seed coat is fused to outer ovary wall (cereal grains: wheat, rice)
                            (2) Nut - single- ovary wall and seed coat remain separate; ovary wall is very hard (acorn, walnut).
                2. Aggregate fruit - develops from one flower with many ovaries (blackberry, raspberry, and strawberry
                3. Multiple fruit - develops from ovaries of several flowers borne together on the same stalk (pineapple)

IV.  Read: Chapter 21.4 in the Graham textbook
 

Fill in the blanks as you watch the short seed dispersal video:

1. The ___________  carries dandelion seeds over several miles.
 

2. The ____________ of trees gives them a particular advantage when dispatching seeds by air.
 

3. Plants also use  __            ___ to disperse seeds by jet propulsion.  Example: squirting cucumber.
 

4. Some plants send their seeds by sea; some by air; but most in fact use _____   ____ carriers.
 

5. All blackberries on the same tree ripen simultaneously         TRUE or FALSE  (Circle one)
 

6. Elephants aid in the dispersal of _______    ___  seeds.  (the name of the tree)
 

7.  ____    ____  percent of Acacia seeds in elephant dung germinate.