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INTRODUCTION TO BRYOLOGY
Joannes A. Janssens
• HORNWORTS
• LIVERWORTS
• MOSSES
• life cycle
• paleobotany
• moss flora
HORNWORTS
LIVERWORTS
MOSSES
The Life Cycle of Bryophytes
• bryophytes are diplohaplontic plants with a heteromorphic alternation of generations
• within the sporangium spores are formed by meiosis
• protonema and gametophores develop after germination
• antheridia and archegonia produce sperm and eggs
• after fertilization a new, attached sporophyte is formed
spor
gam
spor
gam
gam
spor
spor
gam
gam
spor
STREPTOPHYTE EVOLUTION
origin of embryophytes(Charophyceae)
Anthocerotophyta
Polysporangiophyta
Bryophyta
Marchiantiophyta
flavonoidsloss of pyrenoid
jacketsmulticellular sporophyte
calyptraestalked gametangia
loss of columella and stomataseta reduction
• vascular tissue• branched sporophyte• isomorphic phases• stoma
?
?
?
The Paleobotanical Record of Bryophytes
• Sporognites (Paleozoic, Devonian)
• Diettertia montanensis (Mesozoic, Cretaceous)
• Aulacomnium heterostichoides (Tertiary, Eocene)
• Calliergon aftonianum (Pliocene-interglacial Pleistocene)
Sporognites Halle (1913, 1936)
Diettertia montanensis Brown & Robinson (1974)
Aulacomnium
heterostichoides
Janssens et al.
(1979),
compared with
A.
heterostichum
Calliergon aftonianum Steere
(1942)
The Paleobotanical Record of Bryophytes: Conclusions
• earliest fossils are all liverworts (Silurian-Devonian), mosses are Carboniferous-Permian, hornworts first evidence only in Cretaceous
• no Paleozoic fossils can be attributed to any known class of bryophytes
• Mesozoic fossils suggest explosive evolution, and many lineages are presently extinct
• most present-day classes originated in Cretaceous (co-evolution with Angiosperms?) but no extant genera are known before the Eocene
• Tertiary fossils are very similar to extant taxa; present-day ranges were established
• Quaternary fossils are indistinguishable from present-day modifications of living species
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