BFG Ch 9: flowers Flashcards
At what location does the apical meristem start making the flower?
at the “pedicel”.
The stem bearing the flower parts is called the receptacle
Calyx
Outer whorl of flowers
Sepals
temporary protective scales around an unopened bud
incomplete flowers
blossoms that lack one of the parts of a whole flower (the calyx with several sepals)
Corolla
showpiece of a flower.
the layer of petals. Visual attractant for animals and insects
Perianth of the flower is made of what two parts?
the calyx and the corolla
What is flower color usually related to?
the vision of the visitors
bees like blues and violets,
hummingbirds like red
Tepals
perianth consists of only one whorl of leaves called tepals.
ex. of tulips. The tepals just change color
Components of the male reproductive structure, the Stamens
filament (stalk)
anther (tip)
pollen (within the anther)
Pollen
contains two cells. One divides to form two sperm cells.
The other burrows the hole into the female tract
Components of the female reproductive structure, the Pistil
Stigma (top; sticky receptive surface for pollen)
style (elevates stigma to the right position)
ovary (becames a fruit, contains undeveloped seeds or “Ovules”)
Flower parts can be completely separate or..
fused into tubes partially like in foxgloves and stuff.
How can parianth parts be arranged?
usually symmetrically around the central point of the flower
Actinomorphic: spokes on a wheel
zygomorphic: irregular forms
Describe how pollination by animals occurs and why it’s advantageous
anthers dust pollen on the animal’s body
both anthers and stigma are strategically positioned to make contact with the animal.
animal delivers pollen to stigma.
Many flowers are precisely engineered for their specific pollinators
More direct and quick than wind or water pollination strategies
How are flowers a roadmap to rewards for pollinators?
they specifically advertise their nectar or pollen using “nectar guides” (the petal color pattern)
Nectaries are glands at the base of petals, stamen, and pistils that secrete nectar.
some species conceal nectar at the bottom of deep flowers
pollinators are often forced into weird positions to get the nectar, and are most certainly being dusted with pollen at that point.
Inflorescences (disc, ray flowers, composite head)
flowers that form singly on upright stalks
have a composite head, which consists of a central cluster of small disc flowers surrounded by a ring of ray flowers
form ideal landing pads for insects/pollinators
lots of nectar
Morphology of plants that pollinate by wind and how it works
large number of flowers clustered on upper branches
vast amounts of pollen released to wind; small amount actually lands on flowers
most ancient form of pollination (gymnosperms)
evolved before insects; many species of monocots do this.
wind pollinated dicots exist too
some aquatic species do this as well using wind on water to push male flowers close to female flowers.
pollination alternative: hybridization
can’t find your own plant? well hybridize with some other plant then.
adaptations: outbreeding and how to prevent self-fertilization
avoiding self-fertilization chemically via methods to cross-breed with good pollination strategies
stigma and anthers are usually spatially separated, or mature at different times
monoecious condition
“oe household”
means that one plant bears both types of flowers, male and female
dioecious species
two flower types are borne by separate individuals (each plant is male or female, not both)
self-pollination
precludes genetic diversity via hybridization, but it’s a last resort when no other reproduciton is available.
cleistogamy
closed marriage
refers to the type of flowers that remain closed and reproduce with themselves
Pollen tube
forms when pollen is on the stigma.
grows through the pistil’s tissues to reach the ovule and fertilize the egg.
fueled by the stigma itself
