4/15/21

1

Flowering Plants •  Characteristics of

Angiosperms –  Flowers –  Ovaries and Fruits

•  Parts of a flower •  Life cycle

–  Male and female gametophytes

–  Double fertilization •  Why so many species

of Flowering Plants?

•  Start fungi? April 16, 2021

Vascular Plants

(bryophytes) plants N

onvascular

Plants

Liverworts

Mosses

Hornworts

plants vascular Seedless

Vascular plants

Lycophytes

Vascular Independent Sporophyte Roots

Ferns, etc

Gymnosperms

Seeds Angiosperms 500

Seed plants

450 400 350 300 50 0 Millions of years ago (mya)

1

2

3 Megaphylls

Microphylls

Gametophyte dominant

Flowering plants diversified recently

ßTertiary

ß Origin of flowering plants

Some derived features of Angiosperms

•  Flowers •  Ovule enclosed in an ovary •  Fruits •  Double fertilization

Angiosperms – the flowering plants

Stamen Carpel or pistil

Petal Sepal

Ovule inside the ovary Male and female gametes in same structure – the flower

(a) Archaefructus sinensis, a 125- million-year-old fossil

(b) Artist’s reconstruction of Archaefructus sinensis

Carpel

Stamen

5 cm

Figure 30.11

4/15/21

2

Carpels and Stamens Evolved from Leaflike Structures Angiosperms – female parts Stigma

Carpel or pistil Style

Ovary

Ovule

Female gametophyte is inside the ovule Ovule is inside the ovary

Angiosperms – male parts

Stamen Anther

The male gametophyte is inside the pollen grain

Anther

Mature flower on sporophyte plant (2n) Ovary

Embryo (2n) Endosperm (3n)

Seed coat (2n)

Female Gametophyte (in ovule)

Egg cell (n)

Style

Sperm Pollen tube Stigma

Microspore (n)

Male gametophyte (in pollen grain)

Ovule (2n)

MEIOSIS

MEIOSIS

FERTILIZATION

Key Haploid (n) Diploid (2n)

Angiosperm gametophytes are microscopic

Female gametophyte in ovule-- only 7 cells

Male gametophyte in pollen— only 3 cells!

Angiosperms fertilization Many pollen tubes growing in the style

Female Gametophye (in ovule)

4/15/21

3

Double Fertilization

Embryo

Endosperm

Major groups of angiosperms Living gymnosperms Bennettitales

Amborella

Water lilies

Star anise and relatives

Magnoliids

Monocots

Eudicots

300 250 200 150 100 Millions of years ago

50 0

>250,000 species of angiosperms!

>250,000 species of angiosperms! Why so many angiosperms? •  Hypothesis – coevolution with pollinators

4/15/21

4

Flowers can have specialized pollinators

Stamens

plant-pollinator coevolution

Seeds retained in modified ovary à fruit

Mechanisms that disperse seeds by explosive action

Wings

Seeds within berries and other edible fruits

Barbs

Fruits