Pedicularis flammea, Disko - a hemi-parasite
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Comments to the table:
Cuscuta (dodder) is sometimes classified in a separate family,
Cuscutaceae, with only one genus, Cuscuta. If so, only Lauraceae
includes both non-parasitic genera (autophytes) and parasitic ones. The
hemiparasitic subfamilies Rinanthoidea and Buchneoidea (Scrophulariaceae)
is now transferred to Orobanchaceae. The three small holoparasitic families
Apodanthaceae, Cytinaceae, and Mitrastemonaceae were earlier included
in Rafflesiaceae. See also the overview
of parasitic families in relation to types of parasitism.
Definitions:
Parasitism occurs, when one plant exploit another and by doing so causes
damage to the first one (the host).
Through a structural-physiological bridge (the haustorium) parasitic
plants absorb water and nutrients from one or more host plants. However,
some other plants acts similarly but here the bridge is the mycelium of
a mycorrhiza forming fungus. Such plants involved in a relationship of
at least three species are now called myco-heterotrophic plants. Many,
if not most, of the plants known as saprophytes seem to be myco-heterotrophic.
Obligate parasites cannot live without a host but facultative parasites
(examples only to be found among hemi-parasites and so far only demonstrated
under laboratory conditions) may survive without a host but in a far less
vigorous condition.
Literature:
The numbers 10, 13, 16-19, 25, and 29 of the Publication
list deal with parasites. The numbers 53-56 are in Danish but rich in
nice colour illustrations. No. 60
about Nordic parasitic plants are in Dansih but with Figure legends in
English.
See also 'About Viscum' and 'Growing
Viscum' (mistletoe).
The classical scientific book on parasites is: J. Kuijt, 1969: The Biology
of Parasitic Flowering Plants.
There are plenty of colour photographs in H S Heide-Jørgensen 2008:
Parasitic flowering plants.
There are plenty of entries on the WEB dealing with parasitic plants,
and the most comprehensive is:
http://www.science.siu.edu/parasitic-plants/
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S. Heide-Jørgensen, November, 2008
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