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20.2 Classification of Plants
Seedless Nonvascular
Plants
20.2 Classification of Plants
Seedless Non-Vascular Plants
Three groups
hornwort
mosses
Leafy liverwort
20.2
Classification of Plants
Evolutionary
Relationships
Other Bryophytes
Green
Alga
20.2 Classification of Plants
Seedless nonvascular plants.
• Nonvascular plants grow close to the ground to
absorb water and nutrients.
• Most abundant in humid, temperate or tropical
regions
• Usually no conductive tissue, sometimes poorly
developed tissue
20.2 Classification of Plants
• Seedless plants rely on free-standing water for
reproduction.
• NEED MOIST ENVIRONMENT, when active
• Mosses reproduce by branching and fragmentation, by
regeneration from tiny pieces of leaves or stems, and by
the production of spores.
• The spore, under favorable conditions, germinates and
grows into a branching green thread.
20.2 Classification of Plants
Seedless nonvascular plants.
– Liverworts
- often grow on wet rocks or
in greenhouses
- can be thallose or leafy
20.2 Classification of Plants
• Hornworts
– found in tropical forests and along streams
– flat, lobed body with little green “horns”
20.2 Classification of Plants
• Mosses
– most common seedless nonvascular plants
– There are approximately 12,000 species of moss
classified in the Bryophyta
– sphagnum moss commonly used by humans as “peat”
20.2 Classification of Plants
Many small plants bearing the name moss are in fact not
mosses.
• The “moss” found on the north side of trees is the green
alga Pleurococcus; Irish moss is a red alga.
• Beard lichen (beard moss), Iceland moss, oak moss, and
reindeer moss are lichens.
• Spanish moss is a common name for both a lichen and
an air plant of the pineapple family (Bromeliaceae).
• Club moss is a fern ally in the family Lycopodiaceae.
20.2 Classification of Plants
• Mosses existed as early as the
Permian Period (299 to 251
million years ago), and more than
100 species have been identified
from fossils of the Paleogene and
Neogene periods (65.5 to 2.6
million years ago). (yes they are
older than dinosaurs)
20.2 Classification of Plants
Importance of moss
• Mosses break down exposed substrata, releasing
nutrients for the use of more complex plants that
succeed them.
• They aid in soil-erosion control by providing surface
cover and absorbing water, and they are important in the
nutrient and water economy of some vegetation types.
• Know as pioneer species. (first organism to inhabit an
area)