3. Most people think of fruit as something fresh from the market, or canned or frozen, to
which you may want to add sugar before eating. However, fruit can be so much more. The
key to understanding the diversity of fruit types is to know that there are many different
strategies for seed dispersal.
Fruits follow flowers in the life cycle of a flowering plant. They are part of the sporophyte
and are diploid. A fruit develops from the ovary of a flower after pollination and ovule
development have occurred. Fruit functions, not only to surround and protect the
developing seeds, but more importantly, to accomplish dispersal. There are many strategies
of seed dispersal, including being carried by wind, water, or animals or even being eaten by
animals.
Words used to describe seed dispersal usually end in –chory and include anemochory for
wind dispersal and epizoochory for being carried on the outside of an animal as well
endozoochory for being carried in the gut of an animal.
Try to guess the mode or strategy of seed dispersal for the following fruits.
FRUIT
7. Blueberries are an example of
a simple fruit. One fruit
develops from the ovary of
each flower.
A first step in categorizng fruit
types is to decide whether the
fruit is simple (derived from
one carpel or the fused
carpels of a single ovary of a
single flower), aggregate
(derived from several separate
carpels of a single flower), or
multiple (derived from the
ovaries of several flowers).
11. Strawberry (not a true berry)
Accessory fruit
Fruits can also be categorized as accessory or not. True fruit (pericarp) develops from the
wall of the ovary and any other tissue involved is considered accessory. Strawberries are
accessory fruits because the flesh edible part develops from the receptacle portion of the
stem of the flower rather than the ovary wall. It is also an aggregate fruit!
12. FLESHY FRUITS
Berries are simple fruits in which all 3 layers (exocarp, mesocarp, and endocarp) of
the pericarp are soft or fleshy, as in grapes and tomatoes. Seeds of berries can
usually resist digestion and can be transported in the gut of an animal. See the next
two slides for different types of berries.
13. A pepo, like the watermelon or any other squash, is a berry with a hard exocarp.
14. A hesperidium, as in the citrus fruits, is a berry with a leathery exocarp.
15. Drupes, as in peaches and plums, are fruits with a stony and inedible endocarp. Whereas an
animal may eat a berry and transport seeds in their gut, drupe seeds are protected by the
inedible pit and are usually discarded and left behind after the rest of the fruit is eaten.
16. Coconut is an interesting
kind of drupe with a
fibrous mesocarp for
water dispersal and an
endosperm within the
seed that comes in both
a solid and a liquid form.
Most of us never see
coconuts until after the
fibrous exocarp and
mesocarp (husk) have
been removed.
17. A pome is a kind of fleshy fruit in which the pericarp (from the ovary wall) forms a papery
core that surrounds the seeds. The fleshy, edible portion of the fruit develops from
specialized stem tissue, called the hypanthium (of a perigynous flower). Pomes, by definition,
are accessory fruits!
18. drupe
caryopsis
DRY FRUITS
All of the above fruits are classified as fleshy. Other fruits are dry at maturity. A
caryopsis, like corn and other grains, is a simple, dry, and single-seeded fruit in
which the pericarp is tightly fused to the seed coat. A corn kernel is not jut a
seed, but an entire fruit.
19. nut
samara nut
achene
DRY INDEHISCENT FRUITS
Other dry fruits that are also indehiscent (do not split open to release seeds at
maturity) include the wind dispersed samara, the single-seeded achene with the
seed attached at a single point inside the fruit (shell of a sunflower seed), and a
nut with its single, unattached seed.
20. legume follicle
capsule
DRY DEHISCENT FRUITS
Some dry fruits split open to release seeds at maturity
and are therefore termed dehiscent. These include
the legume that splits on two sides (like a peanut), the
capsule (like okra) that splits in several places - one
split per carpel, and the follicle that splits on one side
only.
21. Categories of simple vs. aggregate vs. multiple can be combined
with other categories of fruit type.
The so-called “cones” of sweetgum and magnolia are actually
aggregate follicles.
23. Here is an outline of all the fruit types you are responsible for:
I. Simple vs. aggregate vs. multiple
II. Accessory vs. non-accessory
III. A. Fleshy
1. berry
a. pepo
b. hesperidium
2. drupe
3. pome
B. Dry
1. indehiscent
a. caryopsis
b. samara
c. achene
d. nut
2. dehiscent
a. legume
b. capsule
c. follicle
Editor's Notes
A very good morning to everyone present here, respected teachers, & my batchmates….. I welcome u all, myself SHANKAR LAL KUMAWAT …. Starting my presentation
My research topic Is…….