Reproduction in Angiospermophytes

1. Reproduction in Angiospermophytes Chapter 38 38-1

2. Dicots: Parts in 4’s or 5’s Monocot: Parts in 3’s Monocot vs. dicot flowers: left is spiderwort, a monocot; right is phlox. a dicot.

3. The flower is the reproductive unit of an angiospermophyte Is this a monocot or dicot? How do you know? Sketch & Label the parts: Petal Stigma Style Anther Filament Sepals Ovary

4. The flower is the reproductive unit of an angiospermophyte Which parts are “male” and “female”? Petal Stigma Female: Pistol Or Carpel Style Anther Male Ovary Filament Sepals

5. What are the functions? Functions: Petal – attracts pollinators (insects/small birds/bats) Stigma – pollen landing site Style – pollen tube grows down style from stigma to ovary Anther – contains pollen Filament – supports anther Sepals – cover/protect developing flower. Ovary – contains ovules which contain egg nuclei & develop into seeds when fertilized.

6. Reproduction in Angiosperms • Pollination – pollen carried from anther of one flower to the stigma of another.

7. Can you name some types of animal pollinators?

8. Fig. 38.4ba Moth on Yucca Flower

9. Fig. 38.4bb Blowfly on carrion flower

10. Fig. 38.4bc Long-nosed bat feeding on cactus flower at night.

11. Fig. 38.4bd Hummingbird drinking nectar of columbine flower.

12. Pollination

13. Reproduction in Angiosperms • Fertilization – pollen tube grows down from the stigma to the ovary, through the style. Pollen is delivered to the ovum and fertilization begins. Fig. 38.6-3 Growth of pollen tube & double fertilization.

14. Pollination Tube Formation

15. Can you name some types seed dispersal by wind?

16. Reproduction in Angiosperms • Seed Dispersal – Once the seed has developed into the ovule, it is ready for dispersal. Water/wind dispersal: Coconut seed embryo,endosperm, and endocarpinside buoyant husk Fig 38.11aa

17. Wind dispersal Fig 38.11ab Winged seed of the tropical Asianclimbing gourd Alsomitramacrocarpa

18. Wind dispersal Fig 38.11ac Dandelion “seeds” (actually one-seeded fruits)

19. Wind dispersal Fig 38.11ad Winged fruit of a maple

20. Can you name some types seed dispersal by animals?

21. Fig 38.11bb Squirrel hoarding seeds or fruits underground

22. Fig 38.11bc Seeds dispersed in black bear feces

23. Fig 38.11bc Ant carryingseed with nutritious“food body” to itsnest

24. Dicotyledonous Seeds • Dicot seed have two cotyledons & monocots have only one…remember? • Radicle – embryonic root • Cotyledons - embryonic leaves • Plumule – embryonic shoot (epicotyl, young leaves, shoot apical meristem) Figure 38.8a A common garden bean seed

25. Dicotyledonous Seeds • Points to illustrate in your diagram: • Testa – seed coat • Micropyle – hole that allows water to enter • Embryo root - radicle • Embryo shoot - Plumule • Cotyledons – embryonic leaves

27. Germination • Germination is the development of a new plant. • Ideal conditions for germination: • Water (taken in through the micropyle it activates the seed) • Oxygen for respiration • Temperature (ideal for enzyme activity) • pH (ideal for enzyme activity • Light requirement differ between species

28. Germination • Germination is the development of a new plant. • Some seeds have extra, more specialized conditions: • Digested and passed (e.g. Kleingrass digested by cattle) • Fire (e.g. lodge pole pine) • Removal of inhibitors by washing (e.g. beans)

29. Time Lapse of Radish Seeds Sprouting

30. Metabolic Process for Germination of a Starch Seed

31. Germination of a Starch Seed Maltose absorbed by plumule and radicle. Amylase hydrolyses stored starch to maltose Gibberellins cause synthesis of amylase (enzyme) Further hydrolysis breaks maltose into glucose, which is used for respiration in the growing tissues. Synthesis of gibberellins (plant growth hormones) Water is absorbed through the micropyle and activates cells

32. Control of Flowering • Why do plants only flower at certain time of the year? • Flower purpose – allow for pollination, fertilization, & seed dispersal. • Flowers should only bloom when the right pollinator is abundant. These species show seasonal population shifts.

33. Control of Flowering • Some plants (e.g. irises) bloom in long-day conditions (summer) • Some plants (e.g. chrysanthemums) bloom in short-day conditions (autumn-winter) • The control of flowering is achieved through a process called photoperiodism. The critical factor is not actually day-length it is night-length.

34. Chrysanthemums Irises

35. Control of Flowering • Phytochromes are leaf pigments which act as a biological clock. They measure night length in order to control flowering. • Phytochrome red (Pr) produced slowly in the dark. • Phytochrome far-red (Pfr) produced quickly in the daylight. • Levels of Pfr are used in determining the length of night.

36. Control of Flowering • Long Day Plants (LDP’s) need high levels of Pfr if they are to bloom. • Short Day Plants (SDP’s) need low levels of Pfr • In daylight there is a lot of red light from the sun, & some (not much) far-red light is also present • Pr is converted quickly to Pfr in daylight • Pfr is converted slowly back to Pr in darkness.

37. Control of Flowering • In darkness, there is neither red light nor far-red light. Pfr is slowly converted back to Pr • In long nights lots of Pfr is converted to Pr.

38. http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.html

39. Control of Flowering • Long-day plants, e.g. iris, flower when day length reaches a critical period. This allows Pfr to build up to a critical level, stimulating the releases of flowering hormone. • Short-day plants, e.g. chrysanthemum, require a long period of darkness, allowing Pfr to fall below a critical level in order to flower.

40. So…how does it work again?