_Impatiens_—The generic name of the balsam.

_Impervious_—Not to be penetrated by water.

_Insectivorous_—Catching and killing insects, plants that have this power and can absorb the decomposed insects.

_Insoluble_—Substances that do not dissolve in water.

_Intercellular_—Spaces between the cells.

_Internode_—The space between two nodes.

_Involucre_—A whorl of bracts.

_Iodine_—A soluble substance extracted from kelp and used as a test for starch.