I. Seeds
3. A thick protective coat (the seed integument) formed from the megasporangium.
4. Some seeds are modified to aid in their dispersal. For example, pine seeds
possess papery wings that catch in air currents and help to disperse the
new generation.
B.
Gymnosperm
seeds (see
Lecture
19-Gymnosperms)
1. The single
fertilization produces the diploid embryo.
2. The food source
is the haploid megagametophyte.
C. Flowering plant seeds
1. Double fertilization
produces both the diploid embryo and the triploid endosperm
food source (see
Lecture
20-Flowering plants).
2.
Two
classes based on number of cotyledons (modified seed leaves):
i. primary food source endosperm tissue
ii. cotyledon is the absorptive organ that takes in nutrients from the digested
endosperm
iii. example: corn
(fruit,
cross-section)
i. primary food source fleshy food-storing cotyledons which have absorbed
the
endosperm
ii. example:
bean
D. Most important family of seeds used for food: bean or pea family
1. Seeds of bean or
pea family high in protein and oil
E. Many seeds pressed for oil: sunflower, sesame, peanut, soybean
II. The fruit
III. Types of dispersal
B. Wind dispersal
C. Water dispersal - air spaces and corky floats- example:
coconut
with fibrous husk
D. Dispersal by animals
IV. Types of fruits
B. Aggregate fruit develops from one flower with many ovaries
(ex-blackberry,
raspberry)
C.
Multiple
fruit- develops from ovaries of several flowers borne together on same
stalk (ex- pineapple)
D. Accessory fruit- fruit in which the edible part is primarily tissue other
than ovary tissue
(ex-
apple
and
strawberry
- edible flesh from the receptacle)
V. Illustrations of various fruits and fruit types (from Texas A&M):
Test yourself -- Use the fruit
key
Seed Storage
The Seedbank Facility at the
Royal Botanic Garden
The Seed Guide
Review of flower
and fruit types
Fruit facts