multicellular means..
more than one cell TYPE, not just more than one cell
first terrestrial organisms appeared… how did they evolve?
500 mya
-fungi, then plants. animals invade land much later
what is the ancestor of all land plants
green algae
all green plants have
only land plants have
spores, apical meristems (localized growth), and plasmodesmata (cell communication)
land plants innovation
sporophyte
produces cells that undergo meiosis
gametophyte
produces gametes that develop from spores
nonvascular plants
moss life cycle
dominant gametophyte
vascular plants characteristics
tracheids
hollow cell that empties after death, becomes a tube for water in plants
first vascular plant characteristics
rhizoid
not actually roots, hair like extensions underground coming from rhizome
rhizome
underground stem of early vascular plants
dichotomous branching
branch into y shape, youngest part is the end of branch and oldest part is the beginning of the split
origin of leaves
- Fusion of side branches –> megaphylls
lycophytes characteristics
ferns and fern allies types
horsetail, whisk ferns, ferns
horsetail characteristics
unbranched stem, small leaves in whorls
whisk fern characteristics
no leaves, no roots, dichotomous branching
fern characteristics
most diverse, have true leaves and roots, both gametophyte and sporphyte are green, photosynthetic. sporophyte dominant
seed purpose
protect and nourish embryo, allow survival through unfavorable conditions
seed plant nonvascular or vascular
vascular, trees come from seeds