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BRYOPHYTES
Mosses and Their Relatives
BRYOPHYTES
• Lack true stems, leaves, or roots
• Are non-vascular which means they
do not have vascular tissues
• Vascular tissues are specialized to
conduct water and nutrients
• Since they don’t have vascular tissue, how do they get water and nutrients
to all of their cells?
• They must be in a wet environment
• Sperm must swim to eggs
• Need rainfall or dew for at least part of the year
• They cannot grow very tall
• No true roots
• Have rhizoids
• Long, thin cells that anchor them and absorb water and minerals
• Water moves through via osmosis
• Their “leaves” are only one cell layer think to allow for movement of water and
minerals
• Grow in almost all biomes: tropical, temperate and polar
THREE GROUPS
• Mosses
• Liverworts
• Hornworts
MOSSES
• Most common
• Grow in swamps, bogs, near streams and rain forests where there is a lot
of moisture
• Well adapted to wet habitats and poor soil
• Tolerate low temperatures making them the most abundant plant in polar regions
• Green part we are familiar with is the gametophyte
• Thin stalk with capsule at top formed for reproduction is the sporophyte
LIVERWORTS
• Flat plants resembling the shape of a liver
• Broad, flat, thin structure called gametophyte which draws moisture directly
from surface
• Need damp soil nearly year round
• Umbrella like structures for reproduction called sporophytes
• Some can produce asexually via structures called gemmae
• Very cool little system
• Gemmae produced in gemma cup
• Get washed out of cups and can then reproduce via mitosis
HORNWORTS
• Similar to liverworts
• Sporophyte looks like a tiny green horn
LIFE CYCLE: PART 1
• Gametophyte is dominant
• Easily recognizable
• Carries out most of the photosynthesis
• Sporophyte depends on gametophyte to supply water and nutrients
• Reproduction cycle is alternation of generations
• Moss spore germinates (if conditions are correct)
• Grows into protonema (look it up!)
• Rhizoids form that grow into ground
• Shoots form that grow into air
• Form gametophyte
LIFE CYCLE: PART 2
• Gametes develop
• Sperm develop in antheridia
• Eggs develop in archegonia
• Depending on species, may have both structures on one plant or on separate plant
• Sperm release and swim to egg
• Fertilization occurs forming diploid zygote
• Zygote is beginning of sporophyte stage
• Sporophyte grows out of gametophyte
• Haploid spores produced in capsule via meiosis
• When mature, capsule opens, spores released, spread and cycle starts again
ECOLOGY OF MOSSES
• Natural sponges absorbing large amounts of water
• Can be used to reduce water loss from plant containers
• Dead remains accumulate forming thick deposits of peat
• Useful as fuel
• Useful in gardens
• Improves water retention
• Increases soil acidity which is good for some plants