Bryophytes

Outline

Kingdom Plantae

• Tracheophytes (vascular plants)
• Bryophytes (nonvascular plants)

  Characteristics of:

  All members of Plantae and charophycean chlorophytes:

  • chlorophylls a and b, carotenoids
  • chloroplast with two membranes
  • reserve product is starch, stored inside chloroplast by pyrenoids
  • cellulose cell walls
  • cytokinesis by phragmoplast

  All members of Plantae but not charophycean chlorophytes:

  • Life cycle: diplohaplontic, oogamous and heteromorphic
  • spores produced in a sporangium surrounded by sterile cells
  • gametes produced in a gametangium surrounded by sterile cells
    • sperm produced in an antheridium surrounded by sterile cells
    • eggs produced in an archegonium surrounded by sterile cells
  • sporophyte embryo develops inside gametophyte

Bryophytes (probably a polyphyletic grouping)

• Hepatophyta -- liverworts or "hepatics"
• Anthocerophyta -- hornworts
• Bryophyta -- mosses

  Characteristics of bryophytes:

  • no lignified vascular tissues
  • gametophyte is dominant generation
  • antheridia produce biflagellate sperm
  • sporophyte grows on (and is to some degree nutritionally dependent on) gametophyte
  • rhizoids anchor gametophyte to substrate
  • antheridium morphology -- stalk, jacket of sterile cells, spermatogenous cells
  • archegonium morphology -- stalk, venter, neck, egg
  • sporophyte morphology -- foot, (seta,) sporangium, (calyptra)

Bryophyta

Introduction

~9500 named spp

Characteristics

multicellular rhizoids

leaves unlobed, often with central midribs

stomata

some have leptoids and hydroids, primitive conducting cells

two morphologies -- "cushiony" and "feathery"

gametangia associated with paraphyses

Life cycle [see book]

Diversity -- 3 classes with characteristic sporangia

Bryidae -- "true mosses" -- 9000 spp

Sphagnidae -- "peat mosses" -- 350 spp, all members of genus Sphagnum -- grow in bogs

Andreaeidae -- "granite mosses" -- 100 spp -- grow on rocks

Ecological Importance

Important as early pioneer with lichens -- soil making and seed nursery

Grow only with adequate water -- either have a restricted range or are desiccation-tolerant

Bogs are ecosystems with Sphagnum as the keystone species: their presence makes the bog possible

Economic Importance of Sphagnum

Peat moss -- in nurseries

Traditionally used for dressing wounds and as diapers

  Hepatophyta

Introduction

~8500 named spp (e.g., Marchantia)

Two morphologies: thalloid and leafy

unicellular rhizoids, three rows of bi-lobed leaves w/o central midrib on leafy (third usually ventral and reduced)

Life cycle [see book] (note elaters)

Anthocerophyta

100 spp (e.g., Anthoceros)

Morphology [see book]

Life cycle [see book]

 

Vocabulary

click here to go to Bryophyte vocabulary