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
Berry
Thin 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)
Drupe
Thin exocarpFleshy mesocarp Hard stony
endocarp which encases the seed
Cherries, peaches, and plums Exocarp
Mesocarp
Endocarp
Pome
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: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 - pea
Legume pod splits along two seams to disperse seeds
Capsule
Cotton 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
Nuts
One-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 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
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 bean
Thin 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 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)
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
Tomatoes
Native to Andes Mts in South America
First cultivated in Mexico
Spanish Conquistadors introduced tomatoes to Europe in the 16th century
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 plantsAlso 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 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 Varieties
Pome - 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 - Oranges
Members 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 Fruits
Most 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 Orange
Seedless 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
Chestnuts
American chestnut tree was once one of the most abundant trees in North American forests
Wood widely used for furniture, shingles, poles, ships masts
Chestnut Blight
Fungal disease first reported in 1904 in New York
Spread throughout range from Atlantic Coast to Mississippi River
Estimated 1 billion chestnut trees diedChestnuts can resprout from roots but
eventually will succumb to diseaseResearch on blight resistant trees
Durian
Fruit native to southeast Asia, Malaysia, Thailand, Indonesia
Called “King of Fruits”
Durians
Large fruits - 10-15 lbsOften collected from wild although
cultivation is spreadingNot available outside of AsiaCustard-like pulp that is said to be
heavenly
Durians
Said to be the most delicious fruit on Earth and the worst smelling
Sold in open markets but prohibited in many cities
“No durians allowed”