Imbricate
Overlapping structures like shingles on a roof; e.g. scales on an imbricate bud.
Impressed Venation
Veins sunken or below the surface of a leaf.
Incised
Cut sharply, deeply, and irregularly into angular serrations along the leaf margin.
Indehiscent
An organ, e.g. a fruit, that does not split open at maturity (See also Dehiscent).
Internode
Part of the stem between two growing points or nodes.
Involucre
Multiple bracts beneath a flower sometimes holding on into the fruiting stage as in acorn caps on oaks (Quercus).
Involute
Margins rolled towards the top of the leaf.