What is a green plant supported by so it can stand up? water osmotic pressure cell walls

Cell walls

Explanation:

Water is not it, as liquids usually serve no supportive value.

Osmotic pressure is, "the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis, often used to express the concentration of the solution." (Google Dictionary)

Cell walls are rigid shells on the outside of most plants which helps them stay rigid.

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