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BIOL 1902 Lecture Notes - Monotropa Uniflora, Viburnum Lantanoides, Phototropism

2 pages91 viewsFall 2011

Course Code
BIOL 1902
Michael Runtz

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Plants face another nutritional challenge
o Lack of sunlight (shade)
Outgrow competition
Some shade plants have leaves with a LARGE SURFACE AREA
Round-leaved Orchids have LARGE leaves PARALLEL to the ground
Save energy
Big leaves to capture sunlight (adaption)
Chlorophyll b > chlorophyll a
Nature’s Toilet Paper
Bunchberries exhibit Clonal growth leaves are attached to a common
rhizome (clones)
o Can have big leaves or many leaves for this adaption
Phototropism growing towards the light (moving)
Wild Cucumbers grow atop other plants
Tendrils are thigmotropic REALLY sensitive, more than fingertips
Many vines are negatively phototropic
o Moves away from sunlight
o Why negatively?
So it can wrap around plant and climb on it
Tendrils have power of touch
Trilliums have another solution to the shade problem
Many species of SPRING EPHEMERALS grow in deciduous forests
Another solution is to lose the need for sunlight
o Striped Coralroot (no leaves)
How does it get food?
Saprophyte (fungus and plant roots)
Coralroots attain nutrients from mycorrhizae associated with
other plants
Coralroots are mycoheterotrophs
Live like thieves
Indian Pipe does not need sunlight
o Mycorrhizal Associations
Indian Pipe gets nutrients from living plants
Lives like parasite
Shade-dwelling orchids
o Photosynthesize AND steal carbon from other plants through mycorrhizae
Cancerroot has no leaves and NO mychorrhiza
Its roots form hausteria in the cells of other plants, which it finds by tracking their
o Seed detects strigolactones, starts growing, back to where it produced which is a
plant. Burrows inside it, grows hysteria (swellings of plants that sucks out
Dwarf Mistletoe is a holoparasite
Some habitats have lots of sun
o But too much sun can be a problem
o Buttercups have tiny leaves that grow on a 45 degree angle
o Sand dunes are particularly sunny and hot
Dissected leaves have a small surface area
Plants are the same as animals in many, many ways
EXTERNAL FERTILIZATION is when sperm meets egg outside of the body
INTERNAL FERTILIZATION to better guarantee their efforts
Springtails can leave SPERMATOPHORES on the ground for the female to pick up
Most animals use an INTROMITTENT ORGAN for a sperm transfer
Male snakes have two penises called HEMIPENES
During sperm transfer with their PENIS, dragonflies hold females with their CLASPERS
Most animals deliver sperm directly into a female with a special tool called a PENIS
Penis is a tool for delivering sperm
o When needed, will inflate with blood
To find the right mate, many animals ADVERTIZE
American Toads and frogs use AUDITORY ADVERTISEMENTS

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