FRUITS AND SEEDS

Fruits

Part of sexual reproduction unique to angiosperms

Develops from fertilized ovaryProtect the enclosed seeds and aids

in seed dispersalWidely utilized as a significant food

source

Fruit wall or Pericarp

Develops from the ovary wallComposed of three layers

outer exocarp middle mesocarp inner endocarp

Appearance of these three layers varies among different fruit types

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 fruitTypes of simple fleshy fruits

BERRY -HESPERIDIUM -PEPO DRUPE -POME

BerryThin exocarpSoft fleshy

mesocarp Endocarp with one

to many seedsTomatoes, grapes

and dates

Hesperidium Berry with a tough

leathery rind Oranges, lemons,

and other citrus fruitS

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)

DrupeThin exocarpFleshy mesocarp Hard stony

endocarp which encases the seed

Cherries, peaches, and plums Exocarp

Mesocarp

Endocarp

PomeFleshy 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 fruitsDerived from the ovary of a single

carpel or several fused carpelsPericarp may be tough and woody or

thin and paperyTwo types:

dehiscentindehiscent

Dry dehiscent fruits

Split open at maturity to release seedsWind often aids seed dispersalTypes characterized by how they open:

* Follicle - splits open along one seam (magnolia and milkweed)

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

* Capsule - several pores or slits (cotton and poppy)

Legume - peaLegume pod splits

along two seams to disperse seeds

CapsuleCotton fruit is a

capsule splitting open along five lines

Seeds are covered with long hairs (trichomes) which are the commercial cotton fiber

Indehiscent fruits

Do not split open to release seedsCommon types

Achene Samara Grain Nut

ACHENESOne-seeded fruit Pericarp free from

the seed Sunflower “seeds”

SAMARASWinged achenesDispersed by windFruit in maple

trees and ash trees

Grains

Also called caryopsisSingle seeded fruits Pericarp fused to seed coat Fruits of all cereal grasses: wheat,

rice, corn and barley

Wheat grain

Fused seedcoat and ovarywall layers

NutsOne-seeded fruits Hard stony pericarps Hazelnuts, chestnuts,

and acornsOther things

commonly called nuts that are not true nuts but are actually seeds

Fruit Types II: Aggregate fruits

Develop from a single flower with many separate carpels

Raspberries and blackberriesStrawberries also contain accessory

tissue Seeds on the surface are actually

separate achenes inserted on the enlarged, fleshy, red receptacle

Raspberries and Blackberries

Aggregate-Accessory FruitStrawberries 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

one of many ovaries that are fused together

Seed Structure and Germination

Seeds

Develop from the fertilized ovulesInclude 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

Cotyledons attached to and enclose the embryonic plant

Cotyledons occupy the greatest part of the seed

Cotyledons have absorbed the nutrients from the endosperm which may be entirely used up

Dicot seed - Lima beanThin seed coatHilum 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 embryoConsists 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)

Radicle - the embryonic 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 pericarp

Extensive endosperm occupies much of the seed

Small embryo with a single cotyledonPresence of a coleoptile and the

coleorhiza

Seed germination Absorption of water Emergence of the radicleShoot 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

TomatoesNative to Andes Mts

in South AmericaFirst cultivated in

MexicoSpanish

Conquistadors introduced tomatoes to Europe in the 16th century

What is in a name?Name among native peoples in Mexico

was tomatlIn 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 RelativesMember of the family Solanaceae (called

the potato or tomato family)Family known for its poisonous plantsAlso called the nightshade family because

of deadly nightshade and henbane Also called tobacco family

Suspect PlantBecause of the poisonous relatives,

tomatoes were suspected by many as poisonous

Hard reputation to live downIn 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 space shuttle, genetic engineering, and cloning experiments

Apples - Malus pumila

Family RosaceaeLong history of useOne of the first trees

cultivatedNative to Caucasus

Mts of western AsiaMany legends

associated with apples

Apple VarietiesPome - simple accessory fruitHundreds of varieties exist but only a few

dominate the market Delicious, Rome, Gala, McIntosh

Most apple trees are produced by grafting rather than by seeds

Grafting creates thousands of identical copies with the desired traits

Citrus Fruits

Citrus Fruits - OrangesMembers of the family RutaceaeFruit is a hesperidiumRind impregnated with oil glands (oils

important for perfumes and cosmetics)Individual carpels filled with one-celled

juice sacsFruits high in Vitamin C

Citrus FruitsMost citrus are native to southeast AsiaCitrons 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 1565Sweet oranges introduced after 1821 - grafted

onto sour orange rootstockFlorida remains leading orange-producing state

for juicesGrapefruit developed in Caribbean (pummelo x

orange)

Pummelos

Navel OrangeSeedless orange - propagated asexuallyFirst developed in Brazil by an American

missionary in 19th centuryTwo seedlings introduced to California in

1873 - believed that all navel oranges today are descendants of these two trees

Chestnuts - Castanea dentata

Member of the Fagaceae - Oak Family

Nuts have a long history of use

Nuts produced in groups of 3 surrounded by spiny burr (actually bracts)

Individualnuts

Spiny bracts

ChestnutsAmerican chestnut

tree was once one of the most abundant trees in North American forests

Wood widely used for furniture, shingles, poles, ships masts

Chestnut BlightFungal disease first reported in 1904 in New

YorkSpread throughout range from Atlantic Coast

to Mississippi RiverEstimated 1 billion chestnut trees diedChestnuts can resprout from roots but

eventually will succumb to diseaseResearch on blight resistant trees

DurianFruit native to

southeast Asia, Malaysia, Thailand, Indonesia

Called “King of Fruits”

DuriansLarge fruits - 10-15 lbsOften collected from wild although

cultivation is spreadingNot available outside of AsiaCustard-like pulp that is said to be

heavenly

DuriansSaid to be the most delicious fruit on

Earth and the worst smellingSold in open markets but prohibited

in many cities“No durians allowed”