2 ... 16 - Flowers Flashcards
Modified leaf functions
tendrils spines window leaves insect traps bracts to attract pollinators
tendrils
attaches plant to other objects, often nearby plants
spines
provide protection / defense
window leaves
capture sunlight for photosynthesis while allowing the plant to retain water
insect traps
carnivorous plants have modified leaves to function as traps
bracts
floral modifications, serve to attract pollinators
phyllotaxy
arrangement of leaves on a stem (highly ordered)
based on Fibonacci sequence
alternate leaves
one leaf per node
opposite leaves
two leaves per node
whorl
circle of leaves at same level
flower
determinate shoot of the sporophyte, bearing modified leaves for reproduction
angiosperms
flowering plants
4 whorls of flower (exterior to interior)
sepals (collectively calyx)
petals (collectively corolla)
stamen / androecium (male parts)
carpel / gynoecium (female parts)
androecium
filament
anther (contains pollen sacs)
gynoecium
stigma
style
ovary
Complete flowers
have all 4 whorls
Incomplete flowers
missing 1 or more whorls
grass!
perfect flowers
both male and female structures within same flower
imperfect flowers
only stamens or carpels, not both
two types.. monoecious, dioecious
monoecious
separate male or female flowers on same plant
dioecious
separate flowers on separate male and female plants
hypogynous
superior ovary… parts attached below ovary
perigynous
superior ovary… sepals, petals, stamens fused to form cup around ovary
epigynous
inferior ovary, parts attached above ovary
regular flower symmetry
radial symmetry
structures in different whorls are of similar shape and equidistant
irregular flower symmetry
bilateral symmetry
structures in at least one whorl are different
_____ used to determine genes involved in floral organ placement
Mutants
homeotic mutants
several mutants changed identity of specific whorls
A class gene
controls whorl 1 and 2
A class mutant:
- carpel
- stamen
- stamen
- carpel
B class gene
controls whorl 2 and 3
B class mutant:
- sepal
- sepal
- carpel
- carpel
C class gene
controls whorl 3 and 4
C class mutant:
- sepal
- petal
- petal
- sepal
Why is the ABC model important?
- evolutionary context… understanding flower shape
2. genetic engineering perspective… organ types
inflorescence
arrangement of one or more flowers on an axis
spike
sessile (stalkless) flowers on axis
raceme
flowers attached to axis via stalks (pedicels)
panicle
compound raceme (branched pedicels)
umbel
flat topped where pedicels arise from same point on peduncle
head
large receptable with many small flowers (sunflower)
catkin
spike like with unisexual flowers subtended by bracts