Evolution of Angiosperms

Archaefructus sinensis

• Controversy over when this first appeared

• Best bet is 125 MYA

• No sepals or petals, just stamens and carpels. Stamens thought to have attracted pollinators

Phylum Anthophyta

• Non Monocot Paleoherbs– Nymphales (water lilies), Aristolociales (pipe vine)

• Magnoliids– Magnoliales (Magnolia) Laurales (Red Bay)

• Monocotyledones (monocots)– Grasses, lilies, irises, orchids, cattails, palms

• Eudicotyledons (eudicots)– most familiar trees and shrubs (other than conifers and

palms) and many herbs

Aristolochia gigantea- Dutchman’s pipe

Magnoliids: Magnoliaceae – Magnolia grandiflora

Helianthus annuus Sunflower

Asteraceae- Composites

Usually: inferior ovary, stamens 5 fused, petals 5 fused, sepals absent/reduced

Small disk flowers clustered together

Ray flowers around periphery (carpellate or sterile)

Flowers• Angeion (vessel) + sperma (seed) = Angiosperm• Perfect flowers- bisexual, stamens and carpels• Imperfect flowers- unisexual, either staminate or

carpellate– Monoecious species- both staminate and carpellate

flowers on one plant (ex. oaks)– Dioecious species- staminate and carpellate flowers on

separate individuals (ex. willows)

Locate:

• Pedicel

• Receptacle

• Calyx

• Sepals

• Corolla

• Petals

• Tepals

• Stamens

• Filament

• Anthers

• Pistil

• Stigma

• Style

• Ovary

Clustered flowers

-aggregated into different types of inflorescences

Superior ovary- (ex. lily) sepals, petals, and stamens are attached below the ovary

Inferior ovary- sepals, petals and stamens attached near the top of the ovary

Intermediate conditions:

Malus domestica

Example of epigyny

-sepals, petals, stamens apparently arise from the top of the ovary

Pollen grains

-wall protects male gametophyte

-sculpturing of wall is distinctive and species specific

-Lilium longiflorum

Ambrosia psilostachya- western ragweed

Placentation

Parietal

Axile

Free-central

Fruits

• Just as flowers evolve for pollination, fruit evolves for dispersal

• Fruit is a mature ovary

• Types– Simple: one (or united) carpels– Aggregate: many separate carpels from one

ovary (magnolia, raspberry, strawberry)– Multiple fruits: ovaries of >1 flower

(pineapple)

Dry, indehiscent

• Achene- small, single seeded fruit (Ranunculaceae, Polygonaceae)

• Samaras- winged achenes (elms, ashes)• Caryopsis- grain or achene-like fruit in grasses• Schizocarp- splits at maturity into 2+ one-seeded

portions (Apiaceae)

Dry, dehiscent

• Follicle- single carpel, splits down a side (columbines, milkweeds)

• Legume- Fabaceae- like follicles but split down both sides

• Silique- Brassicaceae Mustard family- 2 fused carpels, sides split off at maturity leaving seeds attached to the central portion

• Capsule- compound ovary (superior or inferior) (poppies)

Fleshy Fruits

• Berry- 1-many carpels, each often many-seeded, inner layer of wall fleshy (tomato, date, grape)

• Drupes- 1-many carpels with only 1 seed each, inner layer of fruit stony (peach, cherry, olive)

• Pomes- subfamily in Roseaceae- compound inferior ovary with large fleshy part from the base of the perianth- also an accessory fruit (apple, pear)

Hesperidium

Modes of dispersal

Modes of dispersal

• Wind

• Water

• “Drop” dispersal

• Mechanical

• Animal (ant, insect, mammal): Internal and external