Generally it is thought that silicon is taken by plants up as soluble
monosilicic acid, a neutral species. This quite unusual as most
elements are taken up as cations or anions. The other element thought
to be taken up as a neutral species is boron. Si is thought to be
transported through to plant mostly as monomeric silica, but I think in
some species the xylem sap may get so concentrated that polymers form.
The soluble silica is then concentrated in certain cells- often, but
not exclusively at the end of the xylem stream. Above a certain
concentration it comes out of solution, and forms solid deposits of
amorphous silica (phytoliths). These are not really a "store" as the
process seems irreversible. The phytoliths take the shape of the cells
etc., and have uses in archaeology and palaeoecology as markers.
Functions? Defence against herbivores and pathogens. Helps keep plants
upright (particularly grasses). In soluble form it seems to reduce Al
and heavy metal toxicity.
Hope that helps!
"Jo Schaper" <firstname.lastname@example.org> wrote in
message news:[Only registered users see links. ]...
Thanks Jo. AFAYK, is , such a high Si uptake, common to
all such primitive plants (Fern, Lichen etc)? If yes, then there's
here an interesting link to the origin of multi-cellular plant life.
In marine plankton, the radiolarians, all do have skeletons made
of beautiful microscopic SiO2 structures.
What Si chemistry and physics is involved in their existence &
growth? -- How & in what form do they extract Si from sea water?
What chemical Si-reactions are involved in this transport?
What soluble silicates are there in ocean water?
I have no problems with  presence at all, not even with 
using the rigid SiO2 networks as a the basic inorganic frame
around which the "living" CHNO networks grow and harden
(a bit like in a fiber-glass analogy)... But what I have not seen
a good/elegnat explanation yet for in what form this Si4+ or
H4SiO4 is transported into and through the plant.
<[Only registered users see links. ].uk> wrote in message
Thanks Martin. I too would love to think that  monosilicic acid,
Si(OH)4 or H4SiO4  is the transporting agent for phyto-Si and
I have neither any problems with the rest of your assertions.
Tell me more about the chem and physics of  from rocks like
(polyvalent Me-silicates) granite or feldspar  into the phytoliths
deposits, for it doesn't seem to be a very well known thing.
IIRC, mono  is stable in water and in rather high concentrations
under near freezing conditions, but polymerizes (polycondensates
with water loss) quickly to become immediately insoluble as meta-
silicate, especially with electrolytes (salt) or higher temps present.
Also  is disassociates so weakly that even the H2CO3 from
dissolved CO2 in water will liberate it out of the rocks .
So the explanation for the origin of the necessary  for the phyto-Si
in nature is an "acceptable" one to me. But now the info available to
me for 's next step into the bio domains of the plant gets sparser.
What other events/processes do play a role? Does the root system
alone do the job or are there symbiotic interplays required?
Does the possible presence of Fluoride and Mg / Zn factor in
to form these highly soluble Fluosilicates, SiF6--. compounds?...
Or do heavy metals like tungsten, W, facilitate the H4SiO4 
transport by forming the highly soluble Silico Tungsten acid,
H4[SiO4(W3O9)4], .... and/or Mo & V, who in similar fashion
together with phosphates do form soluble  complexes?
..... or on the organic front does  form those soluble 5-ligand
coordinates (instead of the usual 4) in the presence of your
Xylem-sap, it presumably being mostly a 2-6 C (ring or chain)
keto/aldo carbohydrate agglomerate. Is there a known possibility
that these sugars can substitute, be or use Si(OH)4 as an ligand
and transport this insoluble item  in a "clatherated" soluble
form thru the system until conditions arise inside the plant where
 gets "expelled"/precipitated or exchanged and forms your
Tell me more, Martin, dudes and dudettes. Gimme some urls.
This  chem and physics is fascinating, from its mechanism of
eroding mountain ranges, influencing climate change, being a
necessary building block in the global food chain all the way to
GE-plant modification improvement, and the preparation of hi-tech
electronic nano sized electronic components. Thanks.
"Edward Hennessey" <[Only registered users see links. ]> wrote in message
news:r41Rf.2869$[Only registered users see links. ].pas.earthl ink.net...
ahahaha... yeah, yeah, I bet... ahaha... So, what do the Ruskies
say?... Even if you don't know, Hennessey, your 2 liner still was
good for a chuckle, unless you plagiarized it from the National
Inquirer... well.. even then it would be funny and VERY helpful.
Thanks for the laugh....ahahaha... ahahanson
In article <Y9rRf.41547$CI6.33560@trnddc07>, Hanson wrote:
Don't *know* the answer to that one, but seeing lichens and
ferns happily growing on clean limestones with 2/10th of damn-all
percent silica in their composition, I don't think that all of them
*require* appreciable environmental silicon.
Radiolarians ... yes, many produce siliceous skeletons. Some
produce strontium sulphate skeletons. some produce no skeletons. But
radiolaria are only a relatively small part of the general planktonic
fauna and flora.
Well, having had to work with silicate-based drilling muds (pH
12.3 and higher - keep those face shields on! And they're an absolute
bitch to wash samples in.) I'd suspect that solution-load silicate is
moved as a range of complexes with organic compounds for 2 reasons : as
you point out, in simple inorganic systems the pH required to keep
silicate in solution is high (very alkaline); and the rate of
weathering of rocks (and the *style* of weathering) increases rapidly
as the plant cover increases, and by implication as the quantities of
organic acids and complexing agents increases. But I don't have the
chemistry to put any detail on that.
Seawater silicate concentrations are (generally) appreciably
lower than temperate runoff (river water, essentially), suggesting that
there are some organisms or processes in the ocean that are very
efficient at removing silicate from the oceans.
Come to think of it - ISTR that the effluvia of mid-ocean
hydrothermal systems also have a significant silicate input to the
oceans, which something is removing. Now where did I read that ... it's
Aidan Karley FGS
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
"hanson" <[Only registered users see links. ]> skrev i en meddelelse
I cann't answer your questions, but I've googled something from the
I havn't read this ... it looks promising [Only registered users see links. ]
My own comment. quote
Si++++ makes a geometrically favorably
binding with O in the sense that it perfectly fits the dimple between 4O
atoms stacked as a pyramid. Al+++ is a small ion too and has exchange with
Si. In silicates the SiO4---- tetraedron are considered a building-block,
and it has any imaginary crystaline combination with metals, from pairs of
tetraeder sharing one O and saturates other bindings with Fe++ or Mg++
through to chains, rings, sheets and frameworks sharing more corners
depending of availabillity of Si.
Halfway down the page is an electron microscopic image of opal [Only registered users see links. ]
I don't think that anyone knows why these tiny puff-balls of silica forms in
such an ordered way. It is basically this mystery and that it could be
biologically mediated that cause me to ponder and respond.
This beetle knows how [Only registered users see links. ]
Opal (disordered hydrated silica) [Only registered users see links. ]
Although there is no crystal structure, (meaning a regular arrangement of
atoms) opal does possess a structure nonetheless. Random chains of silicon
and oxygen are packed into extraordinarily tiny spheres. These spheres in
most Opals are irregular in size and inconsistent in concentration. Yet in
Precious Opal, the variety used most often in jewelry, there are many
organized pockets of the spheres. These pockets contain spheres of
approximately equal size and have a regular concentration, or structure, of
General info on flint and chert [Only registered users see links. ]
Cryptocrystalline quartz is simply quartz whose crystals are so small that
they can only be seen with the aid of a high-power microscope. It is formed
geologically from silica that has dissolved from silicate materials. Over
geological time, this amorphous silica gel dehydrates to form microscopic
crystals and eventually becomes what we know physically as rock.
Cryptocrystalline quartz occurs in many varieties. These varieties have been
named based on their color, opacity, banding and other observable physical
features. Technically speaking, the two varieties that account for the vast
majority of "flint" artifact materials are chalcedony and chert.
Other varieties encountered in the artifact world are agate, jasper and
petrified wood. Interestingly, petrified wood is usually wood that has becn
replaced by agate. This same process also occurs with coral, hence the term
Chalcedony Chert and Flint
Chalcedony is a variety of cryptocrystalline quartz with extremely small
crystals and a specific gravity (weight under water, a measure of a
rock/mineral's purity) nearly identical to that of pure quartz. Due to its
very high quartz content and super fine particle matrix, chalcedony has a
very waxy luster.
Chert is composed of larger crystal particles and has a specific gravity
similar that of pure quartz. Due to impurities and larger particle sizes,
chert is somewhat less "quartz-like" than chalcedony. Chert is duller and
more opaque than chalcedony and its luster ranges from non-existant to very
waxy, depending on the individual rock formation.
So what is flint? By mineralogical definition, flint is simply black chert.
It appears that the term "flint" was originally applied to the high quality
black cherts found in England. Over the years names have evolved for local
chert formations/deposits that may include the word "flint" and technically
speaking these would be incorrect more oflen than not. The reality of the
flint verses chert debate is that in most cases it is something like
"splitting hairs", there really is very little difference, chemically
speaking. Artifact collectors tend to call materials that have a more waxy
luster "flints" and those which have less luster to no luster "cherts". The
difference between them lyes in their purity relative to pure quartz and
their matrix particle size. The smaller the particle size and the purer the
material, the more likely we collectors would be to call the material flint.
To a purist, we would be wrong. A generalist would say "close enough".
Note: Some examples of Flint Ridge Flint are known to be 98.93 % pure
ahahaha.... AHAHAHA... a new pinko emerged, a Gennady:
"Michael Hearne" <[Only registered users see links. ]> who wrote in message
news:_zzRf.3939$[Only registered users see links. ].atl.earthl ink.net...
[Pinko-Mikey, the commie]
ahahaha... Hey, Gennady-Mike , don't be so fanatic. I am glad
that you finally see politics for what it is, but you must be full of
Vodka  to have concluded what you typed from what you've
read... ... BTW, we are talking plant chemistry here, my dear
russophile: *** So, what do the Ruskies say? *** comrade Mickey.
Thanks for the laughs.... ahahaha... ahahanson
PS:  Gennady = Russian Toon Superman, ---  Vodka =
Russian Volks-tonic to become like Gennady
The use of the words chert vs flint in the States to describe
cryptocrystalline quartz is based on regional speech variation and state
of manufacture, not color, luster, or any objective standards.
Archeologists and those referring to human worked rock generally use
flint or flints.
Therefore, chert nodules can be worked into flint arrowheads.
Nobody said it had to make sense.
I am not a botanist, nor a botanic chemist. I would suggest you go to
a local botanical garden, or the botany section of a college library and
look up such things as 'natural terrestrial communities' 'acidic soil
ecosystems''alkaline soil ecosystem'(to see how the other half lives)
'sandstone glade' 'chert glade' 'igneous glade' and any other
combination of silic rock name plus landform (prairie, forest, savanna,
fen, bog, etc.)
As a generalization, more primitive plants do tend to populate more
silic environments, (pines on sandstone, deciduous trees on limestone)
but these are generalizations, with many exceptions as some trees and
plants (blackjack oak, post oak) do adapt to silic environments.
A good naturalist can walk through an area and accurately predict either
the rock or the plants if they know the other, plus the amount of
retained moisture and sun which an area gets.
I had to look up all this stuff when I did my thesis--in order to relate
water chemistry to some of the plants, and their possible interaction
with travertine deposition (i.e., was the water, the slope or the plants
controlling deposition) and I found more info than I could absorb or use
by just browsing in ecology,agronomy and silviculture texts.
"Michael Hearne" <[Only registered users see links. ]> wrote in message
news:_zzRf.3939$[Only registered users see links. ].atl.earthl ink.net...
Whatever that missing link was saying, I didn't see until your
kind post because its prior incursions on our group had already
merited the killfile.
I do have a bit of that indicated Russian literature here and, if
someday, perhaps it will serve as grist for posting.