Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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