BIOL 1902 Study Guide - Heterostyly, Pontederia, Plant Reproductive Morphology

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Published on 20 Jul 2012
School
Carleton University
Department
Biology
Course
BIOL 1902
Professor
Some nectar guides are invisible to us
How do plants avoid SELF-POLLINATION?
o SELF-STERILITY or SELF-INCOMPATABILITY
SPATIAL PLACEMENT of sex organs
Pink Lady’s-slippers also employ a placement strategy
o STAMINODE
o Both exits are partially blocked by the STAMINODE and sticky POLLEN MASSES
SPATIAL SEPARATION of sexes
o (A) Separate sexes on the same plant (Monoecious)
Female flowers of conifers are usually near the top of the tree and the
males at the bottom
Why are they high up?
So pollen from the male flowers does not fall on them
o (B) SPATIAL SEPARATION of sexes on different plants (Dioecious)
White Campions plants are either male or female
o PERFECT FLOWERS
o TEMPORAL SEPARATION of sexes
Orange jewelweed flowers start off as males
The male part falls off and the flower becomes female (prevents self-pollination)
o Temporal sex change = DICHOGAMY
o Potrandry = male first
Pickerel-weed has another way of avoiding self-pollination
Flowers appear in different forms (stamens/style) heterostyly
Purple Loosestrife also has three forms of flowers
Because the forms differ in length of the sexual parts, including the STYLES, it is known
as HETEROSTYLY
Some flowers take an active role in the pollination process
o Milkweed has clamping SADDLEBAGS of pollen
Sheep Laurel has BASHING STAMENS
Recall Red Trilliums smell like rotting flesh to attract flies drawn to carrion (Brood site
deception)
There are other forms of deception
o Grass Pink (Calopogon)
o Grass Pink’s amazing SLAM-DUNK trick (Pseudopollen)
Pseudonectaries
Helleborine
o Releases the odours of a plant under attack (wound hormones)
o Attracts predatory wasps
o Provides nectar
o Bees and Fly orchids have another form of deceit!
Bunchberries are also known as POP-FLOWERS!
Twayblades also have explosive sex!
White Water-lily opens first as a female (protogyny)
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Document Summary

Some nectar guides are invisible to us. How do plants avoid self-pollination: self-sterility or self-incompatability. Pink lady"s-slippers also employ a placement strategy: staminode, both exits are partially blocked by the staminode and sticky pollen masses. Spatial separation of sexes (a) separate sexes on the same plant (monoecious) Female flowers of conifers are usually near the top of the tree and the males at the bottom. So pollen from the male flowers does not fall on them (b) spatial separation of sexes on different plants (dioecious) White campions plants are either male or female: perfect flowers, temporal separation of sexes. Orange jewelweed flowers start off as males. The male part falls off and the flower becomes female (prevents self-pollination: temporal sex change = dichogamy, potrandry = male first. Pickerel-weed has another way of avoiding self-pollination. Flowers appear in different forms (stamens/style) heterostyly. Purple loosestrife also has three forms of flowers.

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