Kingdom – Plantae Phylum - Anthophyta Also known as Angiosperms, or to most people flowering plants

Anthophyta - Angiosperms Produce flowers and form seeds enclosed in fruit Fruit protects the embryo inside the seed and aids in seed dispersal Fruit develops from a flowers female reproductive structure

2 classes Monocots (one seed leaf) Common monocots – corn, grass, lilly, and orchid Dicots (2 seed leaves) Common dicots – Maple tree, tomatoes, potatoes, and dandelion

Can be divided by lifespans Annuals (live for one year or less) Corn, beans, tomatoes, and many food crops Biennials (lives for 2 years ) Parsley, carrots, Sweet William, raspberries Perennials (can live for several years) Asparagus, hostas, roses, peonies, coreopsis and many others

Why flowers? location for sexual reproduction in Angiosperms co-evolved with the pollinators symbiotic relationship – all species involved benefit!

Flower Anatomy Many sizes, shapes and colors Most contain the following organs in some shape or form Petals Sepals Stamens Pistols

Petals Usually brightly colored Often have perfume or nectar at the base Provide surface for pollinators to rest on as they feed All of the petals together are called the corolla

Sepals Usually found in a ring at the base or outermost portion of the flower Serve as protective covering for the flower bud All of the sepals together are called the calyx

Stamen – male reproductive structure Made up of the anther and filament The anther is found at the tip of the filament – this is where pollen is produced The number of stamens varies from flower to flower

Pistil/Carpel – female reproductive structure Made up of the Stigma, Style and Ovary The stigma is at the top of the pistil. It’s role is to receive the pollen The style connects the stigma to the ovary The ovary is at the base. It contains ovules that produce eggs The number of ovaries varies in flowers

Complete vs Incomplete Flowers Perfect vs Imperfect Flower Complete flowers: pistils, stamens, sepals and petals Incomplete flower: lacking any of the parts Perfect flower: has both pistils and stamens Imperfect flower: lacks either pistils or stamens

Monoecious vs Dioecious Monoecious –separate male and female flowers on the same plant Ex. Corn, pecans, walnuts, cucumbers, and squash Dioecious – separate male and female plants Ex. Holly, ginkgo, pistachio, and marijuana

Photoperiodism Photoperiodism: response of flowering plants to daily daylight-darkness conditions Ensures all plants of the same species bloom at the same time

Critical Period The specific daylight-darkness conditions that will make flowering begin Day length is not what matters – amount of darkness is what matters The names are misleading – the categories were named before scientists realized it was darkness, not light, that prompted flowering

4 Categories Short-day: daylight is shorter than critical period – asters, poinsettias, strawberries Long-day: daylight is longer than critical period – carnations, petunias, potatoes Day neutral – flowers over a range of daylight hours, day length is not what induces flowering Intermediate day – will not flower if days are longer or shorter than critical period – sugarcane and grass

Pollination & Fertilization Aka – the birds and the bees 

Development of the female gametophyte Inside the flower the sporophyte produces haploid spores Female spores are megaspores The nucleus of the megaspore undergoes mitosis 3 times to produce the female gametophyte One nucleus becomes the egg, another becomes the egg, another two become the central cell.

All of this is taking place inside the ovaries, which are part of the pistil.

Development of the male gametophyte…so much simpler than the female Microspores are produced inside the anther Microspores develop into the male gametophyte – the pollen grain The haploid nucleus undergoes mitosis, but only once One nucleus is the tube nucleus, the other is the generative nucleus

Now that we have sperm and eggs, how do we get them together? POLLINATION! Definition – the transfer of the pollen grain from the anther to the stigma Possible pollinators – wind, water and animals

Adaptations in flowers Some features that attract animals Strong scent Nectar Bright colors Patterns invisible to the human eye

Adaptations in wind pollinated plants Lack of petals – no need to waste energy attracting the wind Overproduction of pollen – to make up for the pollen that never makes it to the stigma

The pollen grain has landed on the stigma, so what’s next The pollen grain has landed on the stigma, so what’s next? Double Fertilization!!

& Vegetative Reproduction Seed Germination & Vegetative Reproduction

Seed germination Dormancy – the period of inactivity in a mature seed Varies greatly between species Ends when the seed germinates Germination – the beginning of the development of the embryo into a new plant

Germination Water, oxygen and warm temperatures activate the metabolism Some seeds have specific requirements Ex. Animals digestive system, freezing temps, extensive soaking in saltwater, specific daylengths, exposure to fire.

Dicot germination Radicle – embryonic root appears first Hypocotyl – portion of stem nearest seed Cotyledon – plants first leaves In monocots the cotyledon remains below the surface

Vegetative reproduction A new plant is produced from a stem, root or leaf This is essentially cloning – producing new plants that are genetically identical to their parents Tissue culture and/or cuttings.

Chapter 24.3 Seeds and Fruit

Why? The seeds and fruits formed help ensure survival of the next generation

Seed formation After fertilization Zygote divides = embryo Triploid cell divides = endosperm Ovule wall = seed coat

Fruit formation Fruit – the structure that contains the seeds of an anthophyte Fruit – the enlarged ovary surrounding the seed Can be made up of other organs as well.

Fruits Fleshy fruits – apples, grapes, melons, tomatoes, cucumbers Dry fruits – peanuts, sunflower seeds, walnuts. The ovary around the seeds hardens

Seed dispersal Fruits aid in dispersal Dispersal reduces competition Animals – digestion and/or carrying the seed on the body Wind – dandelion, tumbleweed Water – coconut and water lilies

Pictures – from flower to fruit http://www.cas.vanderbilt.edu/bioimages/pages/fruit-devel.htm

What about seedless fruit? Ex. Watermelon and bananas Triploid plants – prevents meiosis from happening and no gametes are produced So where do the plants come from if there are no viable seeds?

Bananas – vegetative reproduction Watermelons – Cross a diploid with a tetraploid to produce a triploid seed Diploid (2) + Tetraploid (4) = 6 sets of chromosomes Divide 6 by meiosis to get 3 sets of chromosomes. Pollination triggers fruit formation – without seeds. The plants must be grown with a diploid variety for pollen

Seed germination Dormancy – the period of inactivity in a mature seed Varies greatly between species Ends when the seed germinates Germination – the beginning of the development of the embryo into a new plant

Germination Water – activates the metabolism Some seeds have specific requirements Ex. Animals digestive system, freezing temps, extensive soaking in saltwater, specific daylengths, exposure to fire.

Dicot germination Radicle – embryonic root appears first Hypocotyl – portion of stem nearest seed Cotyledon – plants first leaves In monocots the cotyledon remains below the surface

Vegetative reproduction A new plant is produced from a stem, root or leaf This is essentially cloning – producing new plants that are genetically identical to their parents Tissue culture and/or cuttings.