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13 Cards in this Set

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arranged in pairs along the stem and each pair is at right angles to the pair above
Adaptations that enable plants to efficiently photosynthsize
broad, thin leaf blades with the thickness and pigmentation optimal for capturing
- stems, branches, and petioles enabling the organization of leaves on a plant to be
positioned to overlap minimally and capture as much of the light that arrives in the
area of the plant as possible. Some leaves even track the sun’s movement.
- Roots that can grow in any direction to find water - even to a depth of 70 feet!
Derivation of photosynthetic organsisms.
Photosynthetic eukaryotes (plants and algae) are derived from the Endosymbiosis of a
cyanobacterium and a non-photosynthetic eukaryotic cell at some point a long time
many organisms, including us, obtain our nourishment from ingesting or
absorbing carbohydrates produced by other organisms; these are called heterotrophs
(hetero - other; trophs - nourish)
Some plants have evolved to be heterotrophic - either partially or completely. These are
called parasites. an organism that grows, feeds, and is sheltered on, or in, a different organism
at the expense of that organism and contributing nothing to the survival of its host.
Types of symbiosis
mutualism - both organisms benefit
commensalism - one organism benefits, while the other neither benefits or suffers
Parasitism - organism that grows, feeds, and is sheltered on, or in, a different organism
at the expense of that organism and contributing nothing to the survival of its host.
Current families with parasitic plants and history of evolution
Parasitism has evolved perhaps 20 times among flowering plants. In each case the plants
have become parasitic on either other plants or fungi. These include 4 families we
know: Boraginaceae, Scrophulariaceae, Ericaceae, Orchidaceae. In some cases (eg, Orchidaceae), parasitism probably has evolved many times fairly
recently in one family.
In other cases (Rafflesiaceae), parasitism may have evolved a long time ago.
haustorium. This is a sucker-like
swelling on a root or stem which invades a host root or stem and makes a connection
between the vascular tissue of the parasite and host.
Plants that obtain all of their nutrients from parasitism are called holoparasites (or obligate parasites).
some parasites remain capable of photosynthesis, while supplementing their
diet with the host plant nutrients. These plants are called hemiparasites (or
facultative parasites).
Parasite reduction syndrome
1) Loss of leaves - leaves reduced to scales
2) Small overall size of plant - no need for large plants to hold leaves
3) Loss of roots - reduced to short, stumpy projections with haustoria
4) Loss of chlorophyll
5) Loss of genes needed for photosynthesis
6) Fast gene evolution in genes which are not lost
What part do all parasites retain
Flowers! for reprodution
Can trees be parasitic?
Yes, hemiparasitic.