Reproduction in Angiospermophytes (flowers) What is… a flower? How does this work? A close look at a seed… Refer to chapter 27 in text.

The flower isn’t the only reproductive path for many angiosperms What is… a flower? The flower isn’t the only reproductive path for many angiosperms (alternatives include bulbs, tubers, adventitious roots, rhizomes and apomixis, as in dandelions) but flowers allow genetic mixing.… It’s about sex. www.pearlsflowers.com/romance.html

Why are these two here side by side? http://www.wallpaper.net.au/wallpapers/plants-flowers/Delta-Violets-1-1024x768.jpg http://www.wallpaper.net.au/wallpapers/plants-flowers/Jonquil-Flowers-2-1024x768.jpg

Parts of an animal-pollinated eudicot flower: Peduncle Receptacle “draw and label…” Parts of an animal-pollinated eudicot flower: Peduncle Receptacle Sepals, forming a calyx Petals, forming a corolla (attracts right pollinator) Male: stamen anther filament Female: pistil/carpel stigma style ovary (this is a superior ovary…) http://www.amnh.org/learn/biodiversity_counts/ident_help/Parts_Plants/parts_of_flower.htm How will you recall which is which?

perfect (bisexual) flowers bilateral symmetry↓ variations on a theme… : www.easytogrowbulbs.com/browseproducts/Hyacin... radial symmetry ↑ perfect (bisexual) flowers bilateral symmetry↓ inflorescence ↑(cluster) composite (looks like one) of incomplete flowers↑ healing.about.com/.../SuSunflower.htm single-sex flowers: ←dioecious (separate plants) monoecious (different flowers, one plant) e.g.pumpkins → www.keyscorner.com/archives/2005/05/ www.life.uiuc.edu/.../BreedingSystems.html

When to flower? Some are triggered by day length: long-day plants flower when the nights get shorter (spring/summer), short-day plants flower as the nights get longer (fall). Phytochrome: a plant pigment that detects visible light. - The red absorbing form (Pr) shifts to the far-red absorbing form (Pfr) when red light is applied (and vice versa). - In the dark Pfr gradually devolves back to Pr. Pfr promotes flowering in long-day plants, and inhibits flowering in short-day plants.

http://www.mobot.org/jwcross/duckweed/phytochrome.htm

Many flower designs are the result of coevolution How does this work? Many flower designs are the result of coevolution with a mutualistically symbiotic pollinator…. www.fs.fed.us/wildflowers/pollinators/

… though some flowers are designed, with everything hanging out, for wind pollination. Pollination: transfer of pollen to the part of a seed plant containing the ovules. not to be confused with Fertilization: the union of haploid gametes to produce a diploid zygote. www.systbot.uzh.ch/institut/personen/person.p...

- A pollen grain from an anther lands on the stigma. www.tiscali.co.uk/.../hutchinson/m0008009.html - A pollen grain from an anther lands on the stigma. - A pollen tube germinates and grows down the style to the ovule. - The pollen tube delivers two pollen nuclei to the ovule….

Double Fertilization: The pollen tube delivers 2 sperm nuclei to the micropyle. One merges with a female nucleus, making a diploid zygote. The other merges with two female nuclei (polar bodies) to form a triploid endosperm nucleus. www.lclark.edu/~seavey/BotanyFall03/Lecture1.html

“Draw and label a diagram showing the external A close look at a seed… “Draw and label a diagram showing the external and internal structure of a named dicotyledonous seed.” Embryo shoot/ Micropyle /Embryo root /Testa In dicots this is embryo leaf, consisting of endosperm. In monocots this sheaths embryo leaf, transferring nutrients from endosperm. Gymnosperms have 2 to 24 cotyledons, similar to the monocot in design. In the case of synonyms, the one in italics is British. www.kidsgardening.com/onlinecourse/PartI5.htm

Germination: breaking dormancy and starting to grow, How does this seed thing work? Germination: breaking dormancy and starting to grow, when conditions are “right”… Different seed have different triggers: If the area is seasonally dry, it might require heavy rain. If the area is subject to fires, it might require fire (that takes out competitors). If it is an area with extreme winters, it might require a long cold spell to break dormancy. If it is a small seed, it might require light, to indicate it is not deeply buried. If it is distributed by fruit-eating animals, it might require exposure to digestive juices.

Whatever the cues that the timing is right, all seeds follow some common steps: 1. Imbibition: water intake - loosens testa and starts metabolic processes. 2. Gibberellin manufacture - this plant hormone, made in the cotyledon, starts 3. Amylase production – an enzyme which breaks starch down into maltose, which moves to the embryo and provides energy for 4. emergence of the radicle, and growth of the plant.

biology.unm.edu/.../FloweringPlants.htm

How do plants detect day length? What does a dicot seed look like, and how does it germinate? What are the parts of an animal-pollinated flower? (Draw one.) What is the purpose of flowers? What kinds of flowers are there? Distinguish between pollination, fertilization, and seed dispersal

vocabulary list peduncle perfect zygote receptacle inflorescence polar bodies sepal composite embryo shoot calyx complete epicotyl petal incomplete hypocotyl corolla dioecious micropyle stamen monoecious radicle anther long-day plant embryo root filament short-day plant cotyledon pistil phytochrome seed coat carpel pollination testa stigma fertilization germination style pollen grain dormancy ovary pollen tube imbibition radial symmetry double fertilization gibberellin bilateral symmetry amylase