hughes at dogwood.botany.uga.edu
Tue Oct 22 10:13:21 EST 1996
In article <199610221307.GAA18926 at net.bio.net> mvanier at GAES.GRIFFIN.PEACHNET.EDU (Marc van Iersel) writes:
>The only heterotrophic higher plant that I am aware of is Indian pipe
>(Monotropa uniflora). It has no chlorophyll and can no not photosynthesize.
>Their root systems have mycorrhizal fungi that are also associated with
>other, photosynthesizing plants. These fungi transfer sugars from the other
>plant to the Indian pipe. I am not sure, but it is possible that Indian
>pipe also uses decaying organic matter as a food source.
There's also coral roots, Corallorhiza, in the Orchidaceae;
the more directly parasitic dodder, Cuscuta, in the Cuscutaceae;
and in the Orobanchaceae there's squaw-root Conopholus and
beech-drops Epifagus in which a lot of plastid characterization
has been done. Epifagus has about 70 kb of plastid DNA remaining,
and has lost a lot of photosynthetic genes.
Monotropa seeds are very tiny, only about 10 cells long and three
wide constituting the embryo, with what looks like a cluster
of smaller meristematic cells embedded. I think that reduced
seed size is characteristic of heterotropic plants.
The review by Jonathan Leake, New Phytologist, 127, 171-216 (1994)
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