20.2 Classification of Plants Seedless Nonvascular Plants

20.2 Classification of Plants Seedless Non-Vascular Plants Three groups mosses Leafy liverwort hornwort

20.2 Classification of Plants Evolutionary Relationships Green Alga Other Bryophytes

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)