1. Life on Earth Kingdom Plantae
Part 5
Division Anthophyta
(Flowering Plants or Angiosperms)

2. Division: Anthophyta
Largest group in the Plant Kingdom with more than 300,000 species
Seed plants with no archegonia produced
Gametophyte generation highly reduced (7 cells and 8 nuclei in the female and 2 cells and 3 nuclei in the male)
Double fertilization occurs with the formation of endosperm (for nutrition)

3. Division Anthophyta (cont.)
Species produce “flowers” which are often showy with colored petals and or sepals (modified leaves)
Close co-evolution with animal pollinators
Two major classes are recognized:
Liliopsida (monocots)
Magnoliopsida (dicots)

4. Monocots vs. Eudicots Two cotyledons in the embryo
Leaves with “net veins”
Flower parts in 4’s and 5’s
Stem a eustele
Many with secondary growth
Pollen tricolpate
Only one cotyledon in the embryo
Leaves with parallel veins
Flower parts in 3’s
Stem with an atactostele
No true secondary growth
Pollen monocolpate

5. Monocots
Includes:
Iris, grasses, palms, orchids, sedges, yuccas, agaves, lilies

6. Eudicots
Includes:
Poppies, sunflowers, buttercups, oaks, mints, and just about everything else!

7. Flower Structure A “typical” flower has: petals sepals carpels stamens
Trillium

8. Variations on Floral Structure
Primitive flowers are those with many, separate parts with both stamens and carpels
More “advanced” flowers have undergone “fusion” of parts and reduction in numbers of each part; some have separate male and female flowers
With these changes other terms are needed to describe these variations

9. Terminology All the petals of a flower = COROLLA
All the sepals of a flower = CALYX
All petals AND sepals = PERIANTH
All stamens = ANDROECIUM
Fused carpels = PISTIL
All female parts = GYNOECIUM

10. Flower Diagram Hypogynous Flower

11. Arrangement of Floral Parts
All parts attached below the ovary = SUPERIOR OVARY or a HYPOGYNOUS FLOWER

12. Arrangement of Floral Parts
All parts attached above the ovary = INFERIOR OVARY or a EPIGYNOUS FLOWER

13. Arrangement of Floral Parts
Flower parts attached to a floral cup or HYPANTHIUM = PERIGYNOUS FLOWER

14. Epigynous Flower

15. What parts are present? PERFECT FLOWERS have both stamens and carpels
IMPERFECT FLOWERS produce only stamens (staminate flowers) or only carpels (pistillate flowers)
COMPLETE FLOWERS have all 4 flower parts (stamens, carpels, petals, sepals)
INCOMPLETE FLOWERS lack one or more parts

16. Actinomorphic = radial symmetry Zygomorphic = bilateral symmetry
Floral Symmetry
Actinomorphic = radial symmetry
Zygomorphic = bilateral symmetry

17. How are the flowers arranged on the plant?
The flowering branch is called the inflorescence
Many types of arrangements are known (umbel, cyme, corymb, raceme, spike, panicle, and HEAD)
The HEAD is found in members of the sunflower family (Asteraceae)
Composed often of TWO flower types = DISC FLOWERS and RAY FLOWERS

18. Ovary
Head of a Sunflower

19. The HEAD Inflorescence
Ray flower
Disc flowers

20. Other Inflorescences
Daucus (a compound umbel)
Penstamon (a thyrse)

21. Lilac (panicle) and Delphinium (raceme)

22. Life Cycle of Angiosperms (In the Ovule)
Surrounded by the integuments, the megaspore mother cell (2N) undergoes meiosis producing 4 megaspores

23. Life Cycle of Angiosperms (In the Ovule)
Three of the four megaspores die, and one functional one divides 3 times by mitosis forming 8 nuclei (N)
Cell walls are formed making 7 cells with 8 nuclei (mature embryo sac or female gametophyte)

24. Life Cycle of Angiosperms (The Female Gametophyte)
EGG CELL
SYNERGID CELLS
POLAR NUCLEI
ANTIPODAL CELLS

25. Angiosperm Life Cycle (Lily variation: one of many)
Meiosis produces 4 megaspore nuclei
Three of the nuclei FUSE (3N)
Two mitotic divisions follow forming the final female gametophyte (embryo sac)
The (3) antipodal cells are triploid
The synergid cells and egg are haploid
One polar nucleus is 3N, the other 1N

26. Lilium (4-nucleate stage)

27. Lilium Female Gametophyte
EGG CELL
SYNERGID CELLS
POLAR NUCLEI
ANTIPODAL CELLS

28. Lilium (8-nucleate stage)

29. Life Cycle of Angiosperms (In the Anther)
Microspore mother cells (2N) undergo meiosis to form microspores (N)
Microspores divide once by mitosis forming pollen grains (male gametophytes)
TWO cells are present (tube cell and a generative cell)
outer wall (with sporopollenin) is the exine and the inner wall is the intine

30. Lilium anther (xs)

31. Mature Pollen Grains
Generative Cell
Tube Cell
ragweed pollen grain

32. Exine of Lilium Pollen

33. Life Cycle of Angiosperms (Pollination)
Pollen grains are released from the anther and carried (pollination) to the carpel/pistil of the flower or different flower

34. Life Cycle of Angiosperms (Toward Fertilization)
Pollen grain germinates and a pollen tube extends down through the style leading to the ovule
The generative cell divides and two sperm nuclei are released into the ovule

35. Life Cycle of Angiosperms (Fertilization)
One sperm nucleus fuses with the egg nucleus and this zygote will grow to become the embryo
The other sperm nucleus fuses with the polar nuclei forming the primary endosperm nucleus which develops into the endosperm
This process is called DOUBLE FERTILIZATION

36. Double Fertilization egg nucleus 3n polar nucleus sperm nuclei

37. Summary
Therefore, the embryo (the next sporophyte generation) is diploid (2N)
The endosperm tissue, used for nutrition of the embryo, is 3N (2 polar nuclei + sperm nucleus)
Endosperm may be 5N (or other N’s) as in Lilium (3N polar nucleus + 1N polar nucleus +1N sperm nucleus)

38. Summary (cont.)
The integument layers, which surround the female gametophyte mature to become the seed coat
Ovule (with the embryo and endosperm) becomes the seed
The ovary of the flower matures to become the fruit