Lecture 14: Seeds and Fruit • • • • • • Seeds Fruits Fruit types Seed dispersal Video: seed dispersal Real fruit samples What is a seed? • • • • A matured ovule, containing: a plant a food supply covered by a _ Embryo • The seed contains a well-formed multicellular young plant embryo (germ) • Embryo is _ (2n) • 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 (2n) • Food source is the haploid megagametophyte Flowering plant seed • • • • • In angiosperms (flowering plants) there is DOUBLE _ Which produces a diploid (2n) and, A triploid (3n) 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 • • Hesperidium • • Pepo • _ Simple fleshy fruit: pepo • – also a fleshy fruit with a tougher outer rind • All member of the squash family: pumpkin, melons, cucumbers Simple fleshy fruit: pome • 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 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 • It spreads the progeny in order to colonize new environments • Reduces for resources with parents • 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 most plants use as carriers for their seeds? • Blackberries on a tree not ripen simultaneously, why? • What plant elephants help to disperse? How they it? What percentage of these seeds germinate in elephant dung? Why? [...]...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 •... 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... 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... 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... 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... 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... 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. .. 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? ... 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 ... 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:... 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... fleshy fruit: drupe • _ type – outer part of fruit wall is soft and fleshy, inner part is hard and stony • For example: Simple fleshy fruit: pepo • – also a fleshy fruit with