seeds and fruits types & dispersal copyright cmassengale
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Seeds and FruitSeeds and Fruit• Fruits are formed by
seed plants to aid in dispersing seeds
• A seed contains the developing plant embryo in a protective coat (testa)
• Seeds form from ovules fertilized in the ovary
• Ovaries with seeds ripen into dry or fleshy fruits
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Parts of a SeedParts of a Seed• External seed coat or testa• Developing plant embryo• Stored food called endosperm• Seeds may be in one part
(monocot) or two parts (dicots)
MONOCOTMONOCOT
DICOTDICOT
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Gymnosperm Seed
• A single fertilization produces the diploid (2n) embryo
• The food source is the haploid megagametophyte
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Flowering plant seed
In angiosperms (flowering plants) there is
DOUBLE _______________Which produces a diploid ________(2n)
and,A triploid (3n) __________Endosperm is the
food source
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Dicot vs. monocot seed
Dicot has two cotyledons (like bean)
Endosperm (food) is kept in the _________
Monocot has one __________ which absorbs the endosperm tissue during germination (corn)
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FruitIn flowering plants – Fruit is a mature,
ripened o_____ that contains the seedsPericarp – the ovary wall ovary
Fruit typesA. SimpleB. AggregateC. Multiple
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A. Simple fruitA. Simple fruit – develops from a ______
ovary of a single flower.Simple fruits can be either fleshy or
dry when matureSimple fleshy fruit1. __________2. _________
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Simple fleshy fruit1. Berry – entire fruit wall is soft and fleshy at maturity. Inside is slimy.For example, grapes, tomato, etc.
2. _______________ is a berry with tough, leathery rind (peel) Examples: oranges, lemons, other citrus.
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Simple fleshy fruit: drupe
3. _______ type – outer part of fruit wall is soft and fleshy, inner part is hard and stony
For example: ______________________
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Simple fleshy fruit: pepo
4. ________ – also a fleshy fruit with a tougher outer rind
All member of the squash family: pumpkin, melons, cucumbers
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Simple fleshy fruit: pome
5. Pomes: most of the fleshy part of pomes develops from the enlarged base of the perianth (corolla and calyx) that has fused with the ovary wall
Pomes include ___________________
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Simple dry fruit: capsule
Simple dry fruits are dry (not fleshy) at maturity. Simple dry fruits that open at maturity include: capsules and legumes
Capsule – fruit is dry at maturity and splits open along several seams
Example: Cotton
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Simple dry fruit: LegumesLegumes are dry at maturity and split
open along _______ seamsExamples: pea pods, bean pods,
peanut
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Simple dry fruits
Simple dry fruits that do NOT open at maturity include
Caryopsis: seed coat is fused to the ovary wall (cereal grains like ____________________)
Nuts: single-ovary wall and seed coat remain separate, ovary wall is very hard(acorns)
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B. _______________________ fruit develops from one flower
with many separate pistils/carpels, all ripening simultaneously
Examples: strawberry, raspberries, blackberries
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C. Multiple fruitMultiple fruit develops from ovaries of
several flowers borne/fused together on the same stalk
For example: ____________
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What is the purpose of the fruit?The main function of the fruit is to disperse the
seedsDispersal is important because 1. It spreads the progeny in order to colonize
new environments2. Reduces ______________ for resources with
parents3. Reduces the chances of predators
destroying all of the plant’s yearly seed production
Four types of seed dispersal:A. Self dispersalB. ______ dispersalC. Water dispersalD. _______ dispersal copyright cmassengale
A. Self dispersal
Plants disperse their seeds by forceful ejection – explosive fruits!
Witch hazel, squirting cucumber (jet propulsion)
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Self dispersalThe peanut plant sows
(buries) its own seeds!Geocarpic: carpel grows
inside the earth (soil)
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B. Wind dispersalFruit and seeds may have special devices
for wind dispersalPlumes catch wind currents: DandelionTrees take advantage of their great
heights for wind dispersal. Fruits with wings are used to slow the descent to land: maple, ash fruit
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C. ___________ DispersalFruits and/or seeds use flotation devices
to travel by water (in rivers, oceans, etc.)
Fruit may have air spaces and corky floats: for example ________________
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D. Animal dispersalPlants have _____________ with animals to
accomplish seed dispersalMany plants depend on animals for seed
dispersal; they may offer a nutritional reward
Animals learn to recognize ripened fruit colors
Fleshy fruits eaten and dispersed with feces
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Animal dispersalSome dry fruit attach and cling to
animals (they hitchhike on the animals)
Some have Velcro-like hooks that cling to animal fur (burdock, cockleburs)
Others have sticky substances that stick to host (mistletoe)
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Further Study on Seed Dispersal
What carries the dandelion seeds for miles?What feature of trees gives them a particular
advantage when dispersing seeds by air?How does the squirting cucumber disperse its
seeds?Although plants use wind and water, what do
most plants use as carriers for their seeds?Blackberries on a tree do not ripen
simultaneously, why?What plant do elephants help to disperse?
How do they do it? What percentage of these seeds germinate in elephant dung? Why?
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