Please enable JavaScript.
Coggle requires JavaScript to display documents.
Nonvascular Plants: Mosses, Liverworts, and Hornworts (Characters of…
Nonvascular Plants: Mosses, Liverworts, and Hornworts
Characters of Nonvascular Plants
embryophytes that do not have vascular tissue
have multicellular sporangia and gametangia
bodies composed of true parenchyma
all mosses and many liverworts
have leafy stems
almost exclusively terrestrial
have cuticle over much of their bodies
many have stomata
life cycle
alternation of heteromorphic generations
can never grow to be really large
thrive in microhabitats
microhabitats that have too little water or soil]
Classifications of Nonvascular Plants
not known how closely related mosses, liverworts, and hornworts are
treated as 3 distinct divisions
Hepatophyta
#
liverworts
Bryophyta
#
mosses
Anthocerotophyta
#
hornworts
all groups together are called "nonvascular plants"
#
Division Bryophyta: Mosses
Sporophyte Generation
zygote of a moss undergoes a division
foot
the basal cell, develops into a small bulbous tissue
capsule
upper cell grows into a simple apical sporangium
seta
a narrow stalk
located between the foot and sporangium
operculum
apex of the sporangium differentiates as a caplike lid
separates from the rest of the sporangium as cells are torn apart
peristome teeth
cells breaking into 1 or 2 rows of complec teeth
calyptra
layer of cells derived from then neck of the archegonium
covers the apex of the sporangium
Metabolism and Ecology
leaves on moss gametophores
have only a thin, incomplete cuticle
if exposed to dry air for even a few minutes
plant would dry out
this is due to the lack of vascular tissue
many mosses live in moist microhabitats
mosses are important in later establishments of other species
Gametophyte Generation
Morphology
gametophores
leafy stems
grow close together
all moss stems have leaves
stems
little tissue differentiation
tissue called cortex\
Water Transport
hydroids
cells that make up innermost cortex
they conduct water & dissolved minerals
leptoids
cells that resemble sieve cells
majority of mosses lack leptoids and hydroids
instead water is conducted along exterior of their stems
by capillary actions
rhizoids
located at base of stem]
small, multicellular trichome-like structures
only anchor the stem, do not conduct water and minerals
Development
growth begins when a spore germinates
this cell undergoes mitosis
then produces a branched system of similar cells
prootonema
#
the entire network
Reproduction
produces gametangia
all mosses are oogamous
antheridia
the sperm
a short stalk
archegonia
the eggs
shaped like a vase
Division Anthocerotophyta: Hornworts
Gametophyte Generation
development is distinctive
special mucilage chamber forms near the upper surface
cells lining the chamber grow into it and become antheridia
as sperm cells mature, antheridia transform their chloroplast
Sporophyte Generation
have a foot embedded in gametophore tissue
above the foot is a meristem that continuously produces new sporangium tissue
as cells are pushed upward
they grow, differentiate, mature and then die
Division Hepatophyta: Liverworts
Gametophyte Generation
hepatic gametophytes are divided into 2 groups
leafy liverworts
thallose liverworts
their leaves typically have 2 rounded lobes w no midrib
no conducting tissues
leaves are arranged in 3 rows
thallus
the body
a body without roots, stems, and leaves
air pores
large air chambers that open to the exterior
not stomata
no guard cells and cannot be closed
antheridiophore
male gametophore
umbrella shaped outgrowth
archegoniophores
stalked, but apex is a set of radiating fingers
project outwards
Sporophyte Generation
elaters
single, elongate cells with spring-shaped walls ]
some cells do not undergo meiosis
their sporophyte is even less conspicuous than in mosses
they are also dependent on the gametophyte
