Chapter 20. Nonvascular Plants
Division Hepatophyta: Liverworts #
The Gametophyte Generation
thallose liverworts
flat and leafy
thallus = body of a thallose liverwort
air pores = air chambers
thicker body
leafy liverworts
resemble mosses
both gametophyte phases are initiated by spore germination and establishment
use rain to carry sperm
archegnoniophores = fingers
antheridiophore = umbrella shaped outgrowth
can be uni or bisexual
Sporophyte Generation
elasters = long spring cells
most liverwort have a foot, seta, & calyptra
seta is much more delicate
Division Anthocerotophyta: Hornworts
contain oil bodies
inconspicuous
The Gametophyte Generation
distinctive gametangium development
once chamber is broken by growth the antheridium are revealed
archegonia is surrounded but not encased
grow in a chamber
not many protonema before gametophore stage
lifespan less than 1 year
numerous internal chambers
The Spororphyte Generation
all attempts to lab grow a sporophyte have failed.
constant replacement
no foot or discrete sporgangium
push, grow, die
100-150 named species
Division Bryophyta: Mosses
Gametophyte Generation
Reproduction
gametophore produces gametangia
when mature the antheridium breaks open and releases sperm
sometimes both are clustered in certain areas
gametangia = short stalks
both will over in bisexual species
antheridia = microgametangia that produces sperm
archegonia = megagametangia that produces eggs
Water Transport
majority lack hydroids & leptoids
capillaries instead
rhizoids
anchors
base of the sten
hydroids = inner most cortex: conducts water and dissolves minerals
hydroid species typically have leptoids
cells that resembe sieve cells
stacks
typically occur in polytrichae family
perennial
Development
protonema = network of these cells
develops a long, slender chlorophyllus cell
perennial
starts as a spore
by going under mitosis produces a number of branched systems
morphology
gametophores = leafy stems
tightly packed
grow close together
more open & loose in cool areas
grow from apical meristem
stem tissues are the cortex
stem is always slender
outer layer is not the epidermis
in almost every environment
The Sporophyte Generation
operculum = caplike lid
nearly all mosses are homosporous
seta = narrow stalk between foot and sporangium
zygote undergoes transverse fission
small in vascular plants
foot = small bulbous tissue in the archegonium
moss gametophytes are large and photsynthetic
caspule = simple apical sporangium
calyptra = layer of cells originating from the archegonium
peristome teeth = guard cells
Metabolism and Ecology
desiccated mosses are temp resistant
many thrive at low temps
forerunners
dormancy
grow in moist places
size and lack of conductivity are critical
need water
Concepts
true plants
vascular cryptograms
evolution
spermatophytes
nonvascular plants(bryophytes)
Characteristics of Nonvascular Plants
mosses
club mosses are not embryophytes but are lycophytes
typically small
spread quickly via asexual reproduction
Classification of nonvascular plants
Three groups are
liverworts
mosses #
hepatophyta
hornworts
: land - vascular tissues - seeds
vas. tissue but no seeds
embryophytes
no vas. & no seeds
have both vas. tissue and seeds