Date: Wed, 17 May 2000 12:40:14 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1573$foo@default> Subject: _Parasitaxus_
Dear Richard,
> Your reading up on New Caladonian plants, did you read about the
> Parasitaxus, the only parasitic gymnosperm in the world. It is
> totally purple!!
The case of _Parasitaxus_ has been discussed on the parasitic plant
list (pp@opus.labs.agilent.com) some time ago. It seems that this
plant is not really a haustorial parasite (like e.g. _Orobanche_ or
_Lennoa_). It lacks intrusive organs or a defined vascular interface
to the host. Instead, it forms connections to the host plant (also a
member of Podocarpaceae like _Parasitaxus_) via a mycorhizal fungus.
Thus, _Parasitaxus_ probably uses a strategy similar to
mycoheterotrophic plants (like _Monotropa_ or _Corallorhiza_). Many
(all?) gymnosperms have mycorhiza, and _Parasitaxus_ appears just to
be an extreme, heterotrophic representative with reduced leaves. The
extent of nutrient transfer from host to "parasite" is not known
(AFAIK).
BTW: Among mycoheterotrophic plants, there are even a few liverworts
(e.g. _Cryptothallus_) and to some degree also mosses (_Buxbaumia_),
so this mode of heterotrophy is in fact widespread throughout the
plant kingdom, while true (haustorial) parasitism and true (complete-
syndrome-) carnivory are limited to dicotyledons (+ non-monocot
monosulcates, viz. "Magnoliidae" s. lat.). Some mosses can, however,
in exceptional situations behave as scavengers: The nitrophilic moss
_Splachnum_ that usually grows on animal excrements has been found
growing on carrion.
Kind regards
Jan
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