Grass has tiny silica "teeth" on it called phytoliths:
I have trouble understanding how can a plant possibly extract silica from soil and form anything out of it. Silicon dioxide is used for chemistry glassware and can survive nearly anything.
I found that what the plants use is actually monosilicic acid in the form of $Si(OH)_4$, but I have not been able to find how that comes to be in the soil in the first place. Clearly, silicon dioxide does not hydrate in water readily the way potassium oxide does, for example, otherwise glassware would not be a thing.
And even if I knew how does the hydrated form of the oxide form, I still do not understand how do the plants manage to dehydrate it in order to prevent it from being water soluble.
Can someone explain the whole chain from $SiO_2$ through $Si(OH)_4$ back to $SiO_2$ that can be seen in the picture above?