Bio 184 Gymnosperms Notes
Spores – the ‘little feet’ of plants
Spores are launched for two reasons
1. To find place where gametophytes can grow
2. To increase the species’ distribution
The more spores that germinate the higher the plant’s fitness
Sporangia – must be raised as high as possible for further spore distribution
In mosses – sporophyte is always the highest point
i.e. on top of the gametophyte
e.g. Buxbaumia
in ferns – sporophyte is independent of gametophyte
sporophyte can even be a tree
tree – can produce billions of spores
2 reasons why small spores appear better
1. Can travel further and occupy distant lands
2. Possible to make more of them (more is better)
Disadvantage to small spores
Low investment – new plants have slow start
Fern’s changed strategy – invests more in gender that takes care of the zygote
Female gametophyte (megagametophyte) – is a super gametophyte
» Is carrying next generation’s food
» Nutrient loading – happens on sporophyte
» Indirectly providing next sporophyte with head start by directly investing in
gametophyte
» Drop from trees
Wouldn’t be better than asexual redproduction if it weren’t for superior
investment in megagametophyte
Male gametophyte – became tiny
» Microgametophyte – forms from cell divisions within spore wall
» Microgametophyte – can be blown thousands of miles
» Purpose of this is to ensure higher chance of mating
Young plant that develops from zygote
2 infrastructure it must build to become independent
1. Sufficient photosynthetic surface to produce nutrients
2. Anchoring system to support its new ‘solar panels’ and supply them with water for
coolant and reactants
Gymnosperms
Include 4 phyla
1. Cycadophyta
2. Coniferophyta
Spores – the ‘little feet’ of plants
Spores are launched for two reasons
1. To find place where gametophytes can grow
2. To increase the species’ distribution
The more spores that germinate the higher the plant’s fitness
Sporangia – must be raised as high as possible for further spore distribution
In mosses – sporophyte is always the highest point
i.e. on top of the gametophyte
e.g. Buxbaumia
in ferns – sporophyte is independent of gametophyte
sporophyte can even be a tree
tree – can produce billions of spores
2 reasons why small spores appear better
1. Can travel further and occupy distant lands
2. Possible to make more of them (more is better)
Disadvantage to small spores
Low investment – new plants have slow start
Fern’s changed strategy – invests more in gender that takes care of the zygote
Female gametophyte (megagametophyte) – is a super gametophyte
» Is carrying next generation’s food
» Nutrient loading – happens on sporophyte
» Indirectly providing next sporophyte with head start by directly investing in
gametophyte
» Drop from trees
Wouldn’t be better than asexual redproduction if it weren’t for superior
investment in megagametophyte
Male gametophyte – became tiny
» Microgametophyte – forms from cell divisions within spore wall
» Microgametophyte – can be blown thousands of miles
» Purpose of this is to ensure higher chance of mating
Young plant that develops from zygote
2 infrastructure it must build to become independent
1. Sufficient photosynthetic surface to produce nutrients
2. Anchoring system to support its new ‘solar panels’ and supply them with water for
coolant and reactants
Gymnosperms
Include 4 phyla
1. Cycadophyta
2. Coniferophyta
