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
what are the different phylums of gymnosperms
coniferophyta
cycadophyta
ginkgophyta
gnetophyta
what characterizes conifers
- woody secondary growth
- dominant tree species in northern locations
- needle shaped growth
- evergreen perisistent foliage
what are the main families in conifers
pinaceae araucariaceae podocarpaceae sciadopityacea cupressaceae cephalotaxaceae taxaceae
common name for pinaceae
the traditional conifers
what are traits of pinaceae
- mostly evergreen
- needle-like leaves
- monocious
- whorled branches
- resinous
- large female cones
- small male cones
- wind pollination
what are traits of araucariaceae
- mostly large trees
- cones large
- needle or broad leaves
- monocious or diocious
traits of sciadopityaceae
single species
traits of cupressaceae
- mainly scale-like leaves
- woody trees or shrubs
- cones are woody or fleshy
trairs of cephalotaxaceae
- small shrubs or trees
- evergreen spirally aranges leaves
- needle like leaves
- monoecious or dioecious
traits of taxaceae
- evergreen
- small trees or shrubs
- female cones are very specialised
characteristics of female cones in taxaceae
a single seed and a single scale that develops into a fleshy aril resembling a fruit
what is the male structure in conirophyta
microsporophylls organized into a strobili
what happens to microspores in strobili
mitosis
forms pollen
wind dispersion
germinates female egg cell and releases sperm
what happens in the cone of the coniferophyta
- mother diploid cells goes through mitosis
- creates 4 daughter cells but only one lives and becomes megaspore
- megaspores goes through mitosis to create female gamerophyte (archegonia)
cycads characteristics
- woody secondary growths
- short height
- very hard and stiff evergreen leaves
- very slow growth
- all dioecious
what are the famailies in cycads
cycadaceae
strangeriaceae
zamiaceae
traits of cycadaceae
- all woody
- palm like growth
- dioecious
- female cones are actually megasporophylls composed of leaf tissue
traits of strangeriaceae
all species with a fern like growth
traits of zamiaceae
palm like
perennial
evergreen
dioecious
what is the lifecyle of the cycadophyta
- sporophylls for males and females
- males have strobilus structure
- females have megasporophyll structure
characteristics of ginkgos
fan shaped leaves
dioecious
fruit like structure for female gametophytes
what is the lifecycle of ginkgophyta
- male structure: simplified sporophyll with only 2 bracts
- female structure: simplified strobili with only 2 ovules
- seeds protected by foul smelling fruit like structure
characteristics of gnetidae
they share little in common other then dna because they specilized for different habitats
characteristics of gnetum
- woody tropical vines or trees
- superficially appear to be angiosperms
characteristics of epherdra
superficially look like grass or equisetum with cones
characteristics of welwitschia
desert specialist with 2 large leaves which grow spontaneously from the base of the plant
what is the gnetophyta lifecycle
some groups use double fertilization
