Seeds and Fruit Seeds Fruit types Seed dispersal

Seeds and Fruit • • • Seeds Fruit types Seed dispersal Video: seed dispersal Real fruit samples

What is a seed? • • A matured ovule, containing: 1. a plant _____ 2. a food supply 3. covered by a _______

Embryo • The seed contains a well-formed multicellular young plant embryo (germ) • Embryo is _____ (2 n) • It will become a whole plant

Nutritive tissue • Seed contains a food supply • Stored food contains enough energy for the embryo to grow through the soil, when seedling is unable to photosynthesize. • Food source can be the _____, which is ______ (_n) – as a result of double fertilization

Seed coat • A thick protective coat – outer layer of the seed • Formed from the ________ Seed coat

Gymnosperm seed • Single fertilization produces the diploid embryo (2 n) • Food source is the haploid megagametophyte

Flowering plant seed • • • In angiosperms (flowering plants) there is DOUBLE ________ Which produces a diploid ____(2 n) and, A triploid (3 n) _____ Endosperm is the food source

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)

Fruit • In flowering plants – Fruit is a mature, ripened o_____ that contains the seeds • Pericarp – the ovary wall Fruit types • A. Simple • B. Aggregate • C. Multiple ovary

A. Simple fruit • A. Simple fruit – develops from a ______ ovary of a single flower. • Simple fruits can be either fleshy or dry when mature • Simple fleshy fruit • 1. _____ • 2. Hesperidium • 3. _____ • 4. Pepo • 5. _____

Simple fleshy fruit • 1. 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.

Simple fleshy fruit: drupe • 3. _______ type – outer part of fruit wall is soft and fleshy, inner part is hard and stony • For example: ___________

Simple fleshy fruit: pepo • 4. ____ – also a fleshy fruit with a tougher outer rind • All member of the squash family: pumpkin, melons, cucumbers

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 __________

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

Simple dry fruit: Legumes • Legumes are dry at maturity and split open along _______ seams • Examples: pea pods, bean pods, peanut

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)

B. _______ • _____ fruit develops from one flower with many separate pistils/carpels, all ripening simultaneously • Examples: strawberry, raspberries, blackberries

C. Multiple fruit • Multiple fruit develops from ovaries of several flowers borne/fused together on the same stalk • For example: ______

What is the purpose of the fruit? • The main function of the fruit is to disperse the seeds • Dispersal is important because • 1. It spreads the progeny in order to colonize new environments • 2. Reduces _______ for resources with parents • 3. Reduces the chances of predators destroying all of the plant’s yearly seed production • Four types of seed dispersal: • A. Self dispersal • B. ______ dispersal • C. Water dispersal • D. _______ dispersal

A. Self dispersal • Plants disperse their seeds by forceful ejection – explosive fruits! • Witch hazel, squirting cucumber (jet propulsion)

Self dispersal • The peanut plant sows (buries) its own seeds! • Geocarpic: carpel grows inside the earth (soil)

B. Wind dispersal • Fruit and seeds may have special devices for wind dispersal • Plumes catch wind currents: Dandelion • Trees take advantage of their great heights for wind dispersal. Fruits with wings are used to slow the descent to land: maple, ash fruit

C. ______ Dispersal • Fruits and/or seeds use flotation devices to travel by water (in rivers, oceans, etc. ) • Fruit may have air spaces and corky floats: for example ________

D. Animal dispersal • Plants have _______ with animals to accomplish seed dispersal • Many 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

Animal dispersal • Some 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)

Video on seed dispersal • Watch the video, take notes, answer these questions: • 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?