Gymnosperms Flashcards
what is special about gymnosperms
first appearance of sededs, pollen and ovules
what are gymnosperms specialized for
dry or cold temperature extremes
what is pollen
the male gametophyte stage in plants
what is another name for pollen
microgametophyte
what is role of pollen
to germinate and produce sperms
what does the ovule contain
- integument
- nucellus
- megagametophyte
what is pollination
transfer of pollen from the male part of a plant to the female part of a plant
only found in seed plants
what is fertilization
the uniting of male and female gametes to produce a diploid zygote
what are seeds
structure containing an embryonic plant, nutritive substance and a protective outer containing
what is the advantage to seeds
they are desiccation tolerant
they have dormancy mechanisms
what is seed dormanvy
the delaying of germination
what is special about seeds in gymnosperms
- open to the atmosphere
- covered by a single integument
what is special about seeds in angiosperms
completely covered
generally contained in a fruit and 2 integuments
what are cones
a strobilus
modified stem tissues
compound structure containing many seperate areas for pollen or ovule cells
distinct male/female forms
characteristics of female cones
megastrobilus
generally woody and larger
woody bracts= modified stem tissues
characteristics of male cones
microstrobilus
generally herbaceous and smaller
each bract is a microsporophyll
when did seedless vasc plants dominate
when global temperatures where 20 degrees
mostly lycopods