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Chpt 20: Nonvascular Plants (CHARACTERISTICS OF NONVASCULAR (Mosses,…
Chpt 20: Nonvascular Plants
Concepts
Embryophytes
Vascular cryptogams
Non vascular plants(bryophytes)
Nonvascular plants arose first
Spermatophytes
Plants grow as rapidly as photosynthesis permits
Charophytes adapted to living on land
CHARACTERISTICS OF NONVASCULAR
Mosses
Nonvascular plants have no vascular tissue
Have multicellular paranoia and gametangia
Almost exclusively terrestrial
Have a cuticle over much of their body
Life cycle with an alteration of heteromorphic generation
Sporophytes are large plants in leaves n roots
Gametophytes are inside pollen grains
Sporophyte are small and temporary
Gametophyte are large and more prominent generation
CLASSIFICATION OF NONVASCULAR PLANTS
Liverworts, division Hepatophyte
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Hornworts division Anthocerotophyte
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Mosses, division Bryophyta
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Today known as bryophytes
All together called nonvascular plants
DIVISION BRYOPHYTA:MOSSES
THE GAMETOPHYTE GENERATION
MORPHOLOGY
Leafy stems=gametophores
Leafy stems=gametophores
Three ribbons submerge in rapid flowing water
All moss stem have leaves
Not homologous
Mosses are ubiquitous
Lack of cuticle=little protection
Usually grow from an apical meristem
Stem tissues called cortex
Stems have hair but stomata don’t occur
Inner cells are larger
WATER TRANSPORT
Innermost cortex is composed of cells called hydroxide
Hydroids conduct water and dissolve minerals
End walls are partially digested
Leptoids, cells that receive sieve cells
Adjacent parenchyma cells are usually cytoplasmic
Rhizoids= small multicellular trachoma structures
Rhizoids lack chloroplasts
DEVELOPMENT
cell undergoes mitosis
protonema
algal cells have 1/2 large chloroplasts
protonemata are perennial
Reproduction
all mosses are oogamous
antheridia
archegonia
occur in same gametophore
The sporophyte generation
megagametophytes usually have 6 cells
offer little nourishment
sporophyte is by way of endosperm formation
moss sporophyte is never independent
moss zygote undergoes a transverse division
foot absorbs minerals, sugars and water
cell breakage is elaborate and precise
virtually:all mosses=homosporous
METABOLISM AND ECOLOGY
small size and lacking of conducting tissue
stem and leaves can be desiccated
ex) foot of a rock cliff is moist
30% of retained water is okay
mosses may be turgid during winter
desiccated mosses are resistant to high or low temperatures
many mosses can thrive at 0 degree celsius
DIVISION HEPATOPHYTA: LIVERWORTS
GAMETOPHYTE GENERATION
liverworts are small plants
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two groups= leafy and thaliose liverworts
protonemata are never extensive
stem tissue=parenchyma
thallus= no roots leaves stems
many cells contain large oil drops
air pores are not stomata
no guard cells
umbrella shaped outgrowth= antheridiophore
apex is a set of radiating fingers
sporophyte generation
some cells differentiate into elaters
no foot or seta is formed
spores are liberated after decay
Hornworts
Concepts
inconspicuous thalloid plants
never contain oil bodies
chloroplasts have a pyrenoid
gametophytes generation
chlorophyllous lamellae grows upward
does not tolerate drying
receive nitrogen compounds from the nostoc
zygote divided longitudinal
mosses and liverworts divide transversely
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sporophyte generation
multicellular
dont have spirally thickened walls
moisture availability = basal meristem active
death is unknown
meristem that produces new sporangium tissues
