CO 20

1
CO 20
2
Fig. 20.1
3
Fig. 20.2
4
Outline

• Introduction
• Phylum Hepaticophyta - Liverworts
• Leafy Liverworts
• Phylum Anthocerophyta - Hornworts
• Phylum Bryophyta - Mosses

5
Introduction

• About 23,000 species of bryophytes.
• Include mosses, liverworts, and hornworts.
• Habitats range in elevation from sea level up to
  5,500 m or more.
• Bryophytes of all phyla often have mycorrhizal
  fungi associated with their rhizoids.
• In some instances, fungi apparently are at least
  partially parasitic.

6
Introduction

• Peat mosses are ecologically important in bogs.
• Luminous mosses are found in caves and in other
  dark, damp places.
• None have true xylem or phloem.
• Many have hydroids.
• Exhibit alteration of generations.

7
Phylum Hepaticophyta

• Liverworts
• Structure and Form
• Most common liverworts have flattened, lobed
  thalli.
• Gametophyte stage develops from spores.
• When spores germinate they may produce immature
  gametophyte (protonema).

8
Phylum Hepaticophyta

• 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.

9
Fig. 20.5
10
Fig. 20.4a
11
Fig. 20.6a
12
Fig. 20.4b
13
Fig. 20.6b
14
Fig. 20.6
15
Fig. 20.7
16
Fig. 20.6c
17
Asexual Reproduction of Marchantia
18
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.

19
Fig. 20.8
20
Phylum Anthocerophyta

• Hornworts
• Structure and Form
• Mature sporophytes look like miniature
  greenish-blackish rods.
• Only about 100 species worldwide.
• Thalli have pores and cavities filled with
  mucilage, that often contain nitrogen-fixing
  bacteria.

21
Fig. 20.9a
22
Hornwort Sporophyte
23
Hornworts

• Asexual Reproduction
• Fragmentation
• Separation of lobes from thallus.
• Sexual Reproduction
• Archegonia and antheridia are produced in rows
  beneath the upper surface of the gametophytes.
• Have both unisexual and bisexual plants.

24
Phylum Bryophyta

• Mosses
• Structure, Form, and Classes
• About 15,000 species of mosses currently known.
• Divided into three classes
• Peat Mosses
• True Mosses
• Rock Mosses

25
Mosses

• Leaves of moss gametophytes have no mesophyll
  tissue, stomata, or veins.
• Blades are nearly always one-cell thick, and are
  never lobed or divided.
• Initially formed in three ranks and usually end
  up appearing to be arranged in a spiral or
  alternately on an axis that twists as it grows.
• Sexual Reproduction

26
Fig. 20.10
27
Fig. 20.13
28
Fig. 20.11
29
Fig. 20.12
30
Fig. 20.13c
31
Fig. 20.13a
32
Fig. 20.13b
33
Phylum Bryophyta

• Human and Ecological Relevance
• Pioneer Species of Primary Succession
• Indicators of Surface Water
• Packing Material
• Peat Mosses
• Soil Conditioner
• Poultice Material
• Fuel

34
Review

• Introduction
• Phylum Hepaticophyta - Liverworts
• Leafy Liverworts
• Phylum Anthocerophyta - Hornworts
• Phylum Bryophyta - Mosses