1. Fern Morphology and Life Cycle Plant Biology 209 January 14, 2014 Version 140116

2. Megaphylls Siphonosteles Spore dispersal

3. Five lineages are included in the monilophyte clade: Equisetophytes (horsetails) Psilotales (whisk ferns) Three of them are considered “ferns”: Marattiales Ophioglossales (grape ferns) Polypodiales

5. Figure 13.5 Three sexual life cycles differing in the timing of meiosis and fertilization (syngamy) Sporophyte (2n) Gametophyte (n) Blueprint: the Land Plants Life Cycle -74

6. The Sporophyte Phase

7. Sporangia

8. Vegetative Body: the Stem CHARACTERISTICS VARIATION POLYPODIALESSEED PLANTS apical meristem with a single tetrahedral apical initial cell Many initials stem protoxylem in islandsStem protoxylem primitively continuous buds not axillary (buds in other positions) Buds axillary stem vascular tissue in a siphonostele (at least not a eustele) Stem vascular tissue in a eustele wood (and cambium) absentCambium present

9. POLYPODIALESSEED PLANTS apical meristem with a single tetrahedral apical initial cell Many initials

10. stem vascular tissue in a siphonostele (usually)

11. POLYPODIALESSEED PLANTS

12. Vegetative Body: the Stem VARIATION Stems creeping or erect (tree ferns - but no wood!) Siphonostele varies in compaction of leaf gaps. Epidermal coverings (indument) are hairs or scales.

13. Our New England Ferns Have a Creeping Rhizome

14. Rhizome habit: is the underground stem ± upright or is it long-creeping? long-creeping more or less upright

15. Tree ferns have erect stems.

16. ABC D Variations on the siphonostele B,C, and D are dictyostelic siphonosteles because their leaf gaps overlap

17. Indument: of hairs, scales, or both Osmunda Woodsia Dryopteris

18. Indument of Hairs (Lophosoria) Indument of Scales (Dryopteris)

19. Variation in petiole scales of scaly tree ferns (Cyatheaceae)

20. Indument of Hairs and Scales (Phegopteris)

21. Vegetative Body: the Leaf The fern leaf is a megaphyll Vernation is circinate

22. The Frond (Leaf)

23. Fiddleheads (croziers)

24. Walking fern (leaf entire) Christmas fern (leaf once-pinnate) Lady fern (leaf twice-pinnate pinnatisect) Leaf Dissection

25. Reproductive Body: Sporangia Sporangia are commonly borne in clusters called sori They are of the leptosporangiate type They are often covered by an indusium. Sori vary in shape and position.

29. The sorus of Cyrtomium from above, covered by its true indusium

31. Marginal sori of purple- stemmed cliffbrake Abaxial sori of Polypodium

32. Fern sori differ in shape, position, and presence or absence of an indusium

33. Leptosporangia - Sporangia small (ca 0.25 mm in diameter) - Sporangial walls one cell layer thick plus tapetum - Sporangia develop from a single sporangial initial - Sporangia produce relatively few spores (commonly 64) Eusporangia - Sporangia large (> 0.5 mm in diameter) - Sporangial walls several cell layers thick - Sporangia develop from a group of sporangial initials - Sporangia produce a large number of spores.

35. Spore Catapult Video Leptsporangium Structure and Dehiscence

36. Sporangium development tapetum

37. Trilete spore (e.g., Adiantum) Monolete spore (e.g., Polystichum) Fern spores are either trilete or monolete

38. Trilete spore Jamesonia imbricata Monolete spore Lomariopsis guineensis Fern spores are either trilete or monolete

39. The Gametophyte Phase

41. spore wall rhizoid Spore germination and early growth, Ceratopteris

44. General Features of Fern Gametophyte Development

48. Fern sperm are helical and multiflagellate Antheridia

49. from Raven…

53. The transition from zygote to embryonic sporophyte From Raven

55. Stable (versus labile) characters of the Polypodiales: Stems have siphonosteles (most species) Apex has a single tetrahedral apical initial Leaves are megaphylls with circinate vernation (croziers) Sporangia usually abaxial (on the lower surface, i.e. away from the stem), leptosporangiate, in sori (most species) Gametophytes are green and thallose (that is broad and flat), not axial (that is with an elongating meristem).

56. First characters to evaluate in the ferns: Stem habit: erect or creeping, long internodes or short? Leaf shape: broadest at base, middle, above middle? Leaf dissection: once-pinnate, twice pinnate, etc. Indument: of hairs, scales, or both? Sorus shape and position: round and near margin, etc. Indusium: present or absent