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Nonvascular plants – Division Bryophyta, Hepatophyta, Anthocerotophyta General characteristics : 1) dominant gametophyte 2) no true vascular tissue 3) no roots 4) sperm must swim through external water to reach an egg. Mosses
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Nonvascular plants – Division Bryophyta, Hepatophyta, Anthocerotophyta General characteristics: 1) dominant gametophyte 2) no true vascular tissue 3) no roots 4) sperm must swim through external water to reach an egg
Mosses - familiar moss plant is a mature gametophyte (all cells have haploid nuclei) - includes stem-like structure, with attached leafy structures - anchored by rhizoids - have varied growth forms
reproductive organs are gametangia two types 1) archegonia 2) antheridia very small, attached to the tip of a gametophyte "stem“
monoecious species vs. dioecious species
archegonia - flask-shaped - long neck venter (containing an egg); stalk, attaching to stem tip
antheridia - elongate spheres spermatogenous cells (become sperm) jacket of sterile cells stalk
- when mature, antheridia open and release sperm - sperm swim through film of water to reach an archegonium
- sperm swims to egg - fertilization occurs - enclosed embryo forms - embryo develops into a mature sporophyte; attached to the gametophyte
moss sporophyte consists of: a foot a seta a sporangium each sporangium includes: sporogenous tissue (diploid cells) (meiosis of these will produce haploid spores) surrounded by a sporangial wall
dehiscence = opening of a sporangium to release spores - removal of operculum spore dispersal -peristome teeth
spore germination begins the formation of a new gametophyte **mosses can also reproduce asexually by fragmentation
Vascular Plants (seedless vascular plants AND seed plants) shared characteristics: 1) vascular tissue xylem phloem 2) dominant sporophyte - usually includes stems, leaves, roots, and sporangia 3) cuticle - accompanied by stomates
Seedless Vascular Plants: example – ferns sporophyte generation consists of: 1) rhizome 2) fronds 3) adventitious roots 4) sporangia - often in a sorus - sporophyll
sporangium consists of: a sporangial wall sporogenous tissue (later, spores) dehiscence spore dispersal
spore germination - produces multicellular gametophyte (haploid) - gametophyte is a thallus, including rhizoids archegonia and/or antheridia - can be unisexual or bisexual
sperm are released and swim through a film of external water to an archegonium - fertilization of egg (in archegonium) produces a 2n zygote; will produce an embryo; embryo eventually develops into a new adult sporophyte