Fruits and seeds

❚ Part of sexual reproduction unique to angiosperms ❚ Develops from fertilized ovary ❚ Protect the enclosed seeds and aids in seed dispersal ❚ Widely utilized as a significant food sourc

FRUITS AND SEEDS

❚ Part of sexual reproduction unique to

angiosperms

❚ Develops from fertilized ovary

❚ Protect the enclosed seeds and aids in

seed dispersal

❚ Widely utilized as a significant food source

Fruit wall or Pericarp

❚ Develops from the ovary wall

❚ Composed of three layers

Fruit Types I: Simple Fruits

❚ Derived from the ovary of a single carpel

or several fused carpels

❚ Can be fleshy or dry

Type I.a: Simple fleshy fruit

❚ Derived from the ovary of a single carpel or several fused carpels

❚ Often soft and juicy

❚ Seed dispersal occurs when an animal eats the fruit

❚ Types of simple fleshy fruits

❚ Thin exocarp

❚ Soft fleshy mesocarp

❚ Endocarp with one to

many seeds

❚ Tomatoes, grapes

and dates

Pepo

❚ Tough outer rind that has both receptacle tissue and exocarp

❚ Mesocarp and endocarp are fleshy

❚ All members of the squash family

(pumpkins, melons, and cucumbers)

❚ Thin exocarp

❚ Fleshy mesocarp

❚ Hard stony endocarp

which encases the

seed

❚ Cherries, peaches,

❚ Fleshy part develops from the enlarged base of the perianth (calyx and corolla) that is fused to the ovary wall

❚ Apples and pears

Accessory fruits

❚ Contain flower parts other than the ovary

❚ Both the pepo and pome are example

Type I.b: Simple dry fruits

❚ Derived from the ovary of a single carpel

or several fused carpels

❚ Pericarp may be tough and woody or thin and papery

❚ Two types:

❘ dehiscent

❘ indehiscent

Dry dehiscent fruits

❚ Split open at maturity to release seeds

❚ Wind often aids seed dispersal

❚ Types characterized by how they open:

* Follicle - splits open along one seam (magnolia

and milkweed)

* Legume - splits open along two seams (beans and peas)

Legume - pea

❚ Legume pod splits

along two seams to

disperse seeds

❚ Cotton fruit is a

capsule splitting open

along five lines

❚ Seeds are covered

with long hairs

(trichomes) which are

the commercial

cotton fiber

Grains

❚ Also called caryopsis

❚ Single seeded fruits

❚ Pericarp fused to seed coat

❚ Fruits of all cereal grasses: wheat, rice, corn and barley

Wheat grain

Fused seed coat and ovary wall layers

❚ One-seeded fruits

❚ Hard stony pericarps

❚ Hazelnuts, chestnuts, and acorns

❚ Other things commonly called nuts that are not true nuts

Fruit Types II: Aggregate fruits

❚ Develop from a single flower with many separate carpels

❚ Raspberries and blackberries

❚ Strawberries also contain accessory tissue

❙ Seeds on the surface are actually separate achenes inserted on the enlarged, fleshy, red receptacle

Raspberries and Blackberries

Aggregate-Accessory Fruit

❚ Strawberries also

contain accessory

tissue

❚ Seeds on the surface

are actually separate

achenes on enlarged,

fleshy receptacle

Fruit Types III: Multiple fruits

❚ Result from the fusion

of ovaries from many separate flowers on

an inflorescence

❚ Figs and pineapples are examples of

multiple fruits

Seed Structure and

Germination

❚ Develop from the fertilized ovules

❚ Include an embryonic plant and some

form of nutritive tissue within a seed coat

❚ Because of the stored nutrients many

seeds are valuable foods

Dicots and monocots

❚ Refers to the number of seed leaves or cotyledons present in the seed

❚ Dicot seeds have two cotyledons

❚ Monocots have one cotyledons

Dicot seed - Lima bean

❚ Thin seed coat

❚ Hilum and micropyle visible on surface

* Hilum - attachment

* Micropyle - opening in the integuments

❚ If the seed coat is removed the two large food-storing cotyledons are visible

Dicot embryo

❚ Consists of :

❙ Epicotyl - part that develops into the shoot; typically has embryonic leaves - also called a plumule

❙ Hypocotyl - portion of embryo between

cotyledon attachment and radicle (between stem and root)

Monocot seed

❚ Cotyledon transfers food from the

endosperm to the embryo

❚ In several monocot families large amounts

of endosperm are present

Monocot seeds - Corn kernel

❚ Reminder: a grain is a one-seeded fruit in which the seed coat is fused to the

Seed germination

❚ Absorption of water

❚ Emergence of the radicle

❚ Shoot emerges:

❙ In dicots the hypocotyl elongates and breaks

through the soil

❙ In monocots the coleoptile emerges protecting the epicotyl tip

❚ Soon after the tissues are exposed to sunlight, they develop chlorophyll and begin to photosynthesize

What is in a name?

❚ Name among native peoples in Mexico

was tomatl

❚ In Europe there were lots of names for

this fruit - love apple or pomme d’amour

was the French name

❚ Scientific name Lycopersicum esculentum

(meaning edible wolf peach)

Poisonous Relatives

❚ Member of the family Solanaceae (called the potato or tomato family)

❚ Family known for its poisonous plants

❚ Also called the nightshade family because

of deadly nightshade and henbane

❚ Also called tobacco family

Suspect Plant

❚ Because of the poisonous relatives,

tomatoes were suspected by many as

poisonous

❚ Hard reputation to live down

❚ In 1820 Col Robert Johnson ate a bushel

of tomatoes in front of a crowd to prove

they were safe

Popular “vegetable”

❚ Although botanically it is simple fleshy fruit (a berry), in 1893 the Supreme Court ruled

it was a vegetable

❚ Widely used in fresh, canned, dried,

pickled, and processed varieties

❚ Also a favorite experimental tool - used in

Apples - Malus pumila

❚ Family Rosaceae

❚ Long history of use

❚ One of the first trees cultivated

❚ Native to Caucasus Mts of western Asia

❚ Many legends associated with apples

Apple Varieties

dominate the market

❙ Delicious, Rome, Gala, McIntosh

rather than by seeds

copies with the desired traits

Citrus Fruits

Citrus Fruits - Oranges

❚ Members of the family Rutaceae

Citrus Fruits

❚ Most citrus are native to southeast Asia

❚ Citrons first citrus fruit introduced to

Mediterranean countries during Greek and Roman times

❚ Sweet oranges not introduced till 16th

century

Introduction to New World

❚ Spanish and Portuguese explorers introduced

citrus to New World

❚ Sour oranges grown in Florida by 1565

❚ Sweet oranges introduced after 1821 - grafted

onto sour orange rootstock

❚ Florida remains leading orange-producing state for juices

Pummelos

Navel Orange

❚ Seedless orange - propagated asexually

❚ First developed in Brazil by an American missionary in 19th century

❚ Two seedlings introduced to California in

1873 - believed that all navel oranges

today are descendants of these two trees

Chestnuts - Castanea dentata

Spiny bracts

❚ American chestnut

tree was once one of

the most abundant

❚ Estimated 1 billion chestnut trees died

❚ Chestnuts can resprout from roots but

❚ Large fruits - 10-15 lbs

❚ Often collected from wild although cultivation is spreading

❚ Not available outside of Asia

❚ Custard-like pulp that is said to be heavenly