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How do plants reproduce? Depends on plant
Nov 5, 2008 – Pollination ecology … Peter Scott – see 2-page lecture outline
Sexual and asexual repro – evolving & persisting
Consider Agave (so-called century plant –flowers once in life – but also makes suckers, i.e. clones of itself)
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Clonal patches in Dicentra
6 hermaphroditic flowers per 4-yr lifetime ; 1 new tuber
An example of combined sexual –asexual reproduction in plants
Figure 30.1 The Phyla of Living Seed Plants
Produce pollen & ovules
What is pollination?
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Figure 30.3 Pollen Grains (how do they differ from what moss, ferns have for male function?) -NO WATER NECESSARY
Figure 30.5 Cones and Strobili
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Angiosperm
Where are the male and female gametes?
Where is stigma, the receptive female surface?
Figure 30.7 A Generalized Flower
Flowers
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Pollen tubes and ovules
Pollen tubes growing through a tomato style
Figure 30.7 A Generalized Flower
Sexual identity in plants
Most common: hermaphrodite … genetically self-compatible, or self-incompatible.
A single flower, both sexes active, selfing permitted or avoided … thanks to opportunity for style to recognize self pollen.
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Figure 30.7 A Generalized Flower
Why is hermaphrodite flower so often favored?
Does it look like this flower is trying to self-pollinate?
- Efficient* way of being male & female, maximizing reproductive success … *one set of showy flower parts.
-Makes pollen-eating insect contact female parts (improves pollination success)
(other hypotheses)
WIND - Many tree and grass species have non-showy (no petals), wind-pollinated flowers. Petals
only useful if attracting animal pollinators.
“Catkin” flowers (male) of an oak tree
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Animal pollination … showy, rewarding flowers
Kankakee savanna
Bee-adapted plant
species
April Sept
June
May
July
Aug.
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Inventory of insect pollinators – collections necessary, identify under microscope
12 Andrena species (of 58 in state)
Look pretty similar
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Bee FamilyCollet Andren Halict Megach Apidae
# sp
ecie
s
0
20
40
60
80
IndianaKank. savannas so
litar
yso
cial
para
siti
c
Megachileaddenda
Megachilefortis
Osmiadistincta
Osmiapumila
Coelioxyssayi
Hoplitistruncata
Dianthidiumsimile
Heriadesvariolosa
Megachilidae
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Does natural selection favor pollinating behavior per se?
Why have plant-pollinator MUTUALISMS evolved?
A male jack-in-pulpit with exit hole for pollinators at bottom of spathe
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FEMALE jack-in-pulpit with NO exit hole; flies are trapped and die.
Source: Cronquist, Integrated System
Inside of a jack-in-pulpit flowering spathe, showing the slippery “flagpole” and the tiny male or female flowers at the base
