Life on Earth Kingdom Plantae Part III

1. Life on EarthKingdom PlantaePart III “Ferns” Boston fern

2. GAMETOPHYTE SPOROPHYTE Pteridium(bracken fern) Two Life Cycle Stages of Ferns

3. Phylum: Moniliophyta • Subphylum: Pterophyta (typical ferns, including water ferns, tree ferns, and grape ferns) • Subphylum: Psilophyta(wisk ferns or psilophytes) • Subphylum: Sphenophyta(horsetails and scouring rushes)

4. Subphylum: Pteridophyta(“typical ferns”) • Plants with megaphyllous leaves (called fronds) with branched veins • Most species have no “stem” but a perennial rhizome • All species are homosporous except the “water ferns” • Some species produce dimorphic fronds (vegetative and reproductive fronds)

5. Fern Terminology Pinna Rachis

6. Osmunda(fertile andsterile fronds)

7. Frond Development • Fronds develop in a coiled fashion known as circinate vernation • Young, coiled fronds are called fiddleheads • Some ferns are edible at this stage

8. Fern Reproduction • Fern plants ( diploid sporophytes) produce spores by meiosis in sporangia • These sporangia develop in small clusters (called sori) on the underside of the pinnae (or on separate pinnae) • Some species produce a protective indusium partially covering the sorus

9. Fern Sporangia

10. Pinna with Sori (no indusium) sorus

11. Fern Sori with Indusia

12. Frond with Sori and Indusia

13. Fern Sporangia with Annulus Sporangia forcibly eject the spores with the action of the annulus and lip cells

14. Gametophyte Generation • Spores develop by mitosis into haploid, photosynthetic gametophytes • The gametophyte thallus usually produces male antheridia first, then female archegonia • Flagellated sperm fertilize egg cells and the zygote develops into the next sporophyte fern plant

15. Gametophyte Generation

16. Fern Antheridia

17. Young Sporophytes

18. Fern Life Cycle

19. Fern Diversity • Some tropical species are “tree ferns” and produce a erect stem (especially the Order Marattiales) • Many ferns are epiphytes • Some ferns are aquatic (floating) • These “water ferns” are heterosporous, while all other ferns are homosporous • Ferns are important economically as ornamentals

20. Platycerium

21. Pleopeltis polypoides“resurrection fern”

22. Water Ferns (Azolla)

23. Azolla from a Distance

24. Marsilea(another water fern)

25. Marsilea

26. Salvinia and Azolla

27. Tropical Tree Ferns (Marattiales)

28. Tree Fern

29. Tree Fern

30. Grape FernsOphioglossum and Botrychium

31. Botrychium

32. Subphylum: Psilophyta(wisk ferns) • Extant plants superficially similar to rhyniophytes, but now known to be “reduced” ferns • No true roots or leaves; homosporous • Erect “stem” and underground “rhizome” have protostele structure • Dichotomous branching common

33. Psilotum (“wiskfern”) produces trilobed sporangia on flaps of tissue called enations previously viewed as a separate division, the Psilophyta Psilotum

34. Psilotum

35. Tmesipteris(another Psilophytefrom SE Asia and New Zealand)

36. Subphylum: Sphenophyta • Includes “horsetails” and “scouring rushes” • Only one extant genus: Equisteum • Characteristics: • hollow, jointed stems • microphyllous-like leaves • homosporous

37. Equisetum

38. Sheathing Leaves and Plants with Strobili

39. Equisetum (strobilus)

40. Equisetum(cont.) • spores with two wall layers • outer wall is hygroscopic and humidity changes cause unwrapping of the 4 arms (elaters) • this action helps to break up the spore mass in spore dispersal

41. Equisetum spores and elaters