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Re: Aquatic Plants Digest V2 #974
>Roger Miller wrote, Wed, Sept 24:
>...Incidentally, I've noticed filaments extending up from the substrate
>around some of my Cryptocoryne wendtii that grow in fine gravel or sand.
>Could these be something like cyprus knees -- a mechanism for the plant to
>promote the oxygen supply to its roots?
I see these, too in almost all my species of crypts, and I think that
obtaining oxygen is not the primary function of these "aquatic" roots. If
"aerial" refers to roots above the soil in the air, then perhaps "aquatic"
would be the proper term for these roots which are above the soil in the
water. Crypts have large air channels in their roots and seem to like high
organic matter soil, and they get started easily in such soils and grow
quite a few roots before any of the "aquatic" roots become visible. I
think that these roots may serve to get mineral nutrients from the water.
They may also function in trapping and holding debris in flowing waters,
but I have only the vaguest notions how this capability may be helpful to
the plants. it may, over the long time, build a raised bed of crypts that
gets their leaves nearer the surface. Perhaps the trapped debris is a
source of nutrients.
>Subject: Liverworts/hornleaf riverweed
>
>I sent the description of a plant I collected (posted here a few days
>ago) to an extension agent mentioned in the University of Florida web
>site, and he kindly wrote back saying that it sounds like Podostemum
>ceratophyllum (hornleaf riverweed, quite a diminutive and unfair common
>name!). I found some info at:
>http://www.keil.ukans.edu/delta/angio/www/podostem.htm
>and some more querying the Plants database:
>http://plants.usda.gov/plants
>
>Unfortunately, I found no pictures or drawings confirming the presumed
>ID. Any ideas around?
>
>Dionigi
When I saw your first post on this subject I was thinking that your mystery
plant could be a higher tracheophyte plant, because I vaguely remembered
seeing something about a family of plants adapted to clinging to rocks in
rapidly moving water. I found a few references to the family in G. Evelyn
Hutchinson's Treatise on Limnology, Vol. 3, but I never remembered to copy
the family name down and bring it to school where my internet connection
is. The family name is something like Podostemaceae, and there are
something like 130 species, most of them tropical, but at least some
extending into temperate regions. Hutchinson did no more than mention the
family because he was restricting himself to plants that grow in lakes. If
you can get your sample plant to grow in the aquarium, that would be very
interesting.
Paul Krombholz in steamy Jackson, Mississippi where much needed rains
finally arrived.