1. School of Sciences, Lautoka Campus BIO509 Botany Lecture 11: Bryophytes

2. Bryophytes are considered the most primitive form of the land plants and are often conspicuous in moist, terrestrial habitats

3. Are they really plants?

4. Phylum Hepaticophyta – Liverworts
Phylum Anthocerophyta – Hornworts
Phylum Bryophyta – Mosses

5. Learning outcomes
Know the distinguishing features of Kingdom Bryophytes.
Understand how bryophytes are similar and different to higher plants.
Learn the distinguishing features between liverworts, hornworts and mosses.
Know the reproductive structures and lifecycle of a moss.
Understand and appreciate the human and ecological significance of bryophytes.

6. Bryophytes About 23,000 species of bryophytes.
Include mosses, liverworts, and hornworts.
Habitats range in elevation from sea level up to 5,500 meters or more.
Small, low-to-the-ground plants, moist shaded habitats.
Bryophytes of all phyla often have mycorrhizal fungi associated with their rhizoids.

7. General characteristics of Bryophytes
Major pigments (chlorophylls a and b)
Starch as reserve food product
Cellulose in cell walls
Waxy cuticle
Stomata
Lack a true vascular system
Lack true roots, have rhizoids.

8. General reproduction
Mostly sexual reproduction although asexual forms occur.
Gametangia protected from desiccation.
Sperms are the only flagellated cells.
Embryos are formed.
Distinct alternation of generations

9. The gametophyte is the conspicuous and dominant generation.
The gametophyte is nutritionally independent.
The sporophyte remains attached to the gametophyte, and is nutritionally dependent on it.

10. All bryophytes have similar life cycles and habitat
All bryophytes have similar life cycles and habitat. They are differentiated based on their structure and reproduction.

11. Phylum Hepaticophyta – Liverworts
Herbalists thought bryophytes with flattened liver shaped lobes were useful for treating diseases.

12. Liverworts
About 8000 species.
Most common is flattened, lobed (‘leaf-like’) thallus.
Leafy stage is the gametophyte.
Liverworts lack conducting elements, a cuticle and stomata.

13. Have distinct upper and lower surfaces.
One-celled rhizoids that function in anchorage on the lower surface.
When spores germinate they may produce immature gametophyte (protonema).
The gametophyte can be “thallose” or “leafy”

14. Leafy liverworts

15. Thalloid liverworts

16. (Thalloid liverworts)
Best known species are in the genus Marchantia.
Thick thallus that forks dichotomously as it grows.
Consists of parenchyma cells with few, if any, chloroplasts.
Upper surface of the thallus has polygon shaped segments with small boarded pores.

17. Section of Marchantia Thallus

18. Reproduction in Marchantia
Sexual
Male and female gametophores produce antheridia and archegonia.
Flagellated sperm fertilize egg in archegonium.
Embryo (immature sporophyte) develops.
Sporophyte consists of foot, seta, and capsule.

19. Meiosis takes place in the capsule.
Capsule decays and spores aided in their release by spiral shaped elaters.
Asexual
Production of gemmae cups separate that from parental
thallus and grow into new liverwort.

20. Male thallus
Female thallus

22. Marchantia Sporophyte

23. Asexual Reproduction of Marchantia

24. Leafy Liverworts
Always have two rows of partially overlapping “leaves” whose cells contain distinctive oil bodies.
Often have folds and lobes.
Archegonia and antheridia are produced in cup-like structure.
At maturity, sporophyte capsule may be pushed out as the seta elongates.
Germinating spore produces a protonema.

26. Phylum Anthocerophyta - Hornworts

27. Hornworts About 100 known species.
Mature sporophyte looks like miniature, green cattle horn.
Gametophyte look like flimsy versions of liverworts.
Occur in moist, shaded areas.

28. Have only large chloroplast in each cell.
Have rhizoids.
Each chloroplast has a pyrenoid.
Have extensive internal cavities that are inhabited by cynobacteria that fix nitrogen.

29. Sexual reproduction.
Archegonia and antheridia are produced in rows just beneath the upper surface of the gametophyte.

30. Following fertilization the sporophyte grows by increasing length.
The rod-like sporophyte has stomata.
Meiosis occurs within the sporophyte and spores produced are released through splits in sporophyte.

31. Phylum Bryophyta

32. Three different classes
Peat moss true moss rock moss

33. Mosses
About 15,000 species.
“Leaves” of moss gametophyte are one cell thick and lack mesophyll tissue, stomata or veins.
Leaves are spirally arranged on axis resembling stem.
Axis lacks xylem and phloem but has hydroids and leptoids for conducting food and water.

35. Moss reproduction Sexual reproduction
Male and female gametangia are produced at tips of leafy gametophytes.
Sperm are flagellated and reach archegonium by swimming in a film of water.

36. Calyptra sits on top of capsule.
Sporophyte develops in base of archegonium and grows into a foot, seta, and a capsule.
Calyptra sits on top of capsule.
Meiosis takes place in the capsule producing spores.
Peristome teeth at rim of capsule aid in dispersal of spores.
Operculum
Peristome

37. Spores germinate on moist soil and develop into an algal-like protonema
Protonema develops tiny "leafy" buds which will produce the upright gametophytes

39. Fragments of leaves, stems, and rhizoids can develop protonema.
Pieces of a Gametophyte can break off & form new moss plants (fragmentation)
Asexual reproduction

40. Human and ecological relevance
Pioneer Species of primary succession, rapidly colonize bare or burned soil and accumulating organic matter.
Contribute to humus formation.
Reduce flooding and erosion.
Few mosses are a problem to water reservoirs clogging the pipes.
Used for packing and stuffing.

41. Peat mosses are important to humans
Peat mosses belong to class Sphagnidae that contains only one genus Sphagnum.
The Sphagnum sporophyte is different from that of all other mosses, forming a red or black sphere raised up on a  pseudopodium.
Has unusual protonema (disk shaped).
Explosive operculum mechanism for spore dispersal.

42. Peat mosses have impressive water holding capacity
Peat mosses have impressive water holding capacity. A number of species are able to hold 20 or more times their own weight in water

43. Sphagnum-dominated peatlands covers more of the world's land surface than any other single plant genus.
Peatlands store large amounts of organic carbon that is not readily decayed by microorganisms.
Peat is formed fro accumulation and compression of mosses, sedges, grass and other plants growing among them.

44. Sphagnum sp.
Forms extensive peat bogs in northern
latitudes (arctic regions) around world

45. Because of its extraordinary water holding capacity, it is useful for soil conditioning.
Used as seafood packaging material. Live shellfish and other organisms are shipped in peat moss. It is naturally acidic so prevents bacterial and fungal growth
Has antibacterial properties and is used for wound dressings .
During the production of Scotch whiskey, barley is dried over using peat moss - smoky flavour for whiskey

47. Questions are welcome?