Chapter 27, pages 565
Basic Botany-5 20:45-25:51
I. Development of Fruit (using the garden pea as an example)
A. Structure of the carpel before fertilization
1. Pistil - composed of one carpel
2. Carpel structure
a. Dorsal suture - corresponds to the midrib of the leaf
b. Ventral suture - corresponds to the fusion of the two leaf margins
(1) One on each side of the ventral suture
(2) One at the dorsal suture (leaf midrib)
d. Placenta is along the ventral suture and ovules are attached to the placenta
e. Ovary wall is composed of three layers
(1) Outer epidermis
(2) Middle zone several cells thick
(3) Inner epidermis
B. Structure of carpel after fertilization
1. Ovary wall now called pericarp
2. There are three parts to the pericarp:
a. Exocarp - outer epidermal region
b. Mesocarp - middle zone
c. Endocarp - inner layer
3. The floral structures wither and may or may not persist
4. The seeds develop and mature at the same time the ovary wall does
5. Abortive seeds occur - probably unfertilized ovules
II. Kinds of Fruits
A. Simple Fruits - single ovary with either one or many united carpels
1. Dry Pericarp - pericarp is dry when the fruit is mature
a. Dehiscent - pericarp splits open and releases the seed when mature
(2) Follicle
(3) Capsule
(4) Silique
b. Indehiscent - pericarp remains attached to seed when mature, seed not released
(1) Achene
(3) Samara
(4) Schizocarp
(5) Nut
2. Fleshy Pericarp - pericarp wet and juicy when mature
a. Drupe
b. Berry
(1) True Berry
(2) Hesperidium
(3) Pepo
c. Pome
B.
Aggregate Fruits - composed of many
simple
ovaries on one
receptacle
within one
flower growing into a
single
fruit
C.
Multiple Fruits - composed of many simple ovaries on many
receptacles within many
flowers
that grow together in one large single fruit
III. Description of Each Kind of Simple Fruit
a. Dehiscent
b. Fruit from one ovary and one carpel in the ovary
d. Example: Pea Family (Fabaceae)
2. Follicle
a. Dehiscent
b. Fruit from one ovary and one carpel in the ovary
c. Dehisces along one suture
d. Examples: Magnolia and milkweed
3. Capsule
a. Dehiscent
b. Fruit from one ovary that is composed of many carpels
c. Dehisces in one of three ways depending upon species
(1) Lengthwise along sutures between carpels (Example: cotton and Amaryllis)
(2) Pores around the top like a salt shaker (Example: poppy)
(3) Transverse lid like a lid on a pot (Example: purslane, pigweed, plantain)
4. Silique
a. Dehiscent
b. Fruit from one ovary that is composed of two united carpels
c. Dehisces into three portions
(1) Two outer valves
(2) One inner partition containing the seeds
d. Example: Mustard Family (Brassicaceae)
5. Achene
a. Indehiscent
b. Fruit from one ovary that is composed of one carpels
c. Pericarp easily separated from the seed coat
d. Example: strawberry seeds, sunflower seeds
a. Indehiscent
b. Fruit from one ovary that is composed of one carpel
c. Pericarp is firmly united to the seed coat
d. Examples: Wheat, Corn, Oats, Grass Family (Poaceae)
7. Samara
a. Indehiscent
b. Fruit from one ovary that is composed of one carpel
c. Has a wing-like outgrowth on the ovary wall
d. May be one or two seeded
(1) One-seeded Example: elm or ash
(2) Two-seeded Example: boxelder or maple
8. Schizocarp
a. Indehiscent
b. Fruit from one ovary that is composed of two united carpels
(1) The two carpeled ovary splits apart at maturity into two separate carpels
(2) Each half contains a seed with the pericarp still firmly attached to the seed
c. Example: Carrot Family (Apiaceae)
9. Nut
a. Indehiscent
b. Fruit from one ovary that is composed of one carpel
c. Pericarp is hard or stony - the shell of the nut
d. Husk or cupule on some nuts - a modified calyx or involucre
e. Examples: Chestnut, Walnut, Hickory Nut, Acorn, Hazelnut, Beechnut
f. Fruits that are not nuts:
Almond
is a
Drupe,
Brazil
Nut and
Pinyon
Nuts are seeds,
and
Peanuts
are the seeds of a
legume
or pod
10. Drupe
b. Fruit from one ovary that is composed of one carpel
c. Single seed in the center - thus called a stone fruit
d. Structure of the fruit
(1) Endocarp - the hard smooth shell
(2) Mesocarp - edible central juicy portion
(3) Exocarp - skin
e. Examples: Peaches, Apricots, Olives, Cherries, Almonds
11. True Berry
b. Fruit from one ovary that is composed of many carpels
c. Has a very thin skin of exocarp only
d. The seeds are embedded in the fleshy mesocarp and endocarp
e. The mesocarp and endocarp are the edible portions of the fruit
f. Examples: tomatoes and grapes
12. Hesperidium
b. Fruit from one ovary that is composed of many carpels
c. A modified True Berry
(1) Has a thick oily skin of exocarp and mesocarp
(2) Pulp section is the endocarp where the seeds are embedded
(a) The "wedges" are the carpels
(b) Ten carpels with two seeds each
d. Example: Citrus Fruits such as oranges, grapefruits, lemons, limes
13. Pepo
b. Fruit from one ovary that is composed of many carpels
c. A modified True Berry
d. Rind or outer shell of rind is a fusion of the receptacle and the exocarp
e. Fleshy part is the mesocarp and endocarp where the seeds are embedded
f. Examples: Watermelon, Squash, Cucumber, Pumpkin
14. Pome
b. Fruit from one ovary that is composed of five carpels
c. Hypanthium is adnate to the pericarp
d. The fleshy edible portion of this fruit comes from the hypanthium
e. Structure of this fruit
(1) Endocarp - parchment-like material adjacent to the seeds
(2) Mesocarp between the parchment-like material and the coreline
(3) Exocarp - produces the coreline at the outer limit of the carpels
15. Aggregate
a. Fleshy fruit composed of many single carpels
b. Numerous carpels on one
receptacle
within one set of floral leaves (or, numerous
pistils
or ovaries
within a single flower)
c. Examples:
(a) Strawberry
(b) The seeds are the achenes
(c) Fleshy receptacle is what is eaten
(a) Blackberry, Raspberry
(b) The seeds are in each of the little druplets
(c) The fleshy receptacle and the druplets are eaten in the Blackberry
(d) The druplets only are eaten in the Raspberry
16. Multiple
a. Typically a fleshy fruit
b. The enlarged ovaries from several flowers grow together into one single fruit.
c. Formed from the individual
ovaries of several flowers all developing together into one
fruit
d. The individual ovaries
of this fruit type develop into
simple
fruits as described above
but when
mature combine to form one large fruit.
e. Examples:
(1) Mulberry
(a) Each ovary develops into a nutlet enclosed by persistent juicy calyx lobes
(b) Individual ovaries all crowd together and collectively
the entire fruit is called
a mulberry
(2) Fig
(a) Enlarged fleshy receptacle
(b) Flowers small and attached to the inner wall of the receptacle
(c)
Staminate and
pistillate flowers attached to the inside of the
urn-shaped
receptacle
(d) The ovary is one-celled and one-seeded, developing into a nutlet
(e) The entire receptacle with all its little nutlets is the fruit
17. Accessory
a. Accessory tissue is any
part of the fruit that develops fruit-like characteristics that is
not part of
the ovary or
pericarp
b. Examples:
(1) Receptacle of the strawberry and blackberry
(2) Rind of the watermelon
(3) The edible hypanthium of the apple and pear
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