chapter 20
characters of nonvascular plants
classification of nonvascular plants
Division Bryophyta:Mosses
The Gametophyte Generation
The Sporophyte Generation
Division Hepatophyta:Liverworts
The Gametophyte Generation
The Sporophyte Generation
Division Anthrocerotophyta: Hornworts
The Gametophyte Generation
The Sporophyte Generation
they are embryophytes that do not have vascular tissue
exclusively terrestrial and have cuticle over much of their bodies, and many stomata
do not grow to be large
spreads by asexual reproduction
Anthocerotophyta: hornworts
Bryophyta: mosses
hepatophyta: liverworts
in the past, all three were grouped together
morphology
The leafy stems of many moss plants grow together
also known as gametophores
in cool wet areas, they grow more open and loose
most have leaves, but they are not homologous with those of vascular plants
this is because they are part of a gametophyte and not a sporophyte
most grow from a apical meristem that contains a prominent apical cell
most steams are slender and have little tissue differentation
the surface layer is the only diffence from the underlying layers
is not called the epidermis
the difference is the outside cells are slightly narrower
the stem tissues are called the cortex
water transport
composed of cells called hydroids
conduct water and dissolved minerals
are elongated cells that loose their cytoplasm when mature
leptoids
most common in species that have hydroids
cells that resemble sieve cells
majority of mosses lack hydroids and leptoids
rhizoids are at the base of the stem
small, multicolor trichome-like structures that penetrate the surface of a substrate
lack chloroplasts
Development and Reproduction
protonema
long chlorophyllous cell that undergoes mitosis and produces a system of similar cells
antheridia
sperms are produced in the microgametangia
archegonia
eggs occur in the megagametangia
these occur in the same gametophore in bisexual species
foot- small, bulbous tissue located at the bottom of the archegonium
capsule- simple apical sporangium that consistes of out layer sterile cells and inner layer of sterile cells
absorbs sugars, minerals, and water
operculum- caplike lid that separates from the rest of the sporangium
peristome teeth- cell breakage that respond to humidity
calyptra-a layer of cells that derive from the neck of the archegonium
leafy liverworts
thallose liverworts
gametophore resembles moss
have two rounded lobes with no midrib and no conducting tissue
leaves defined in 3 rows
body is sometimes referred to as a thallus
a body without leaves, roots, or stems
has air pores that open to the exterior of the aerenchyma
may either be bisexual or unisexual
male gametophores produce an umbrella-shaped outgrowth called antheridiophore
elaters- single, elongate cells with spring-shaped walls
the substitution for meiosis
small thalloid plants that grow on wet soil, hidden by grass
have numerous chambers internally
is distinctive
archegonia are formed from superficial cells
do not completely surround the egg