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Idioblast - a special cell in a tissue which differs markedly in form, size or contents from other cells in the same tissue.
Imbricate - with overlapping edges.
Imperfect - flowers lacking either pistils or stamens.
Incumbent - resting or leaning upon. Also applied to a pair of cotyledons curving back down the hypocotyl so that the back of one is turned towards the hypocotyl and the back of the other is turned away from it.
Incurvispinus - with inwardly curved spines.
Indigenous - occurring naturally in an area. Not introduced.
Indehiscent - failing to split open at maturity.
i. capable of continuing to grow at an apex or tip.
ii. of sequential flowering from lateral or basal buds to the central or apical bud.
See also: determinate
Inermis - (Latin: unarmed) of a plant or plant part without spines of thorns.
Inferior - below another organ or part.
Inflorescence - a flower cluster, including bracts, on a stalk.
See also: catkin, corymb, cyathium, cyme, fascicle, panicle, raceme, spadix, spike, thyrse umbel
Inorganic - of molecules or chemistry based mainly on elements other than carbon.
See also: Organic.
Insectivorous - trapping and obtaining nutrients from insects.
Integument - the covering of an ovule or other structure.
Intergrading - merging from one form to another by a continuous series of intermediate forms rather than divided into discrete sets.
Internode - part of a stem between two nodes.
Intertextus - interwoven.
Introse - facing inwards.
Involucre - a whorl of small leaves close underneath a flower or flower cluster.
Irradiance - the amount of light energy illuminating the Earth per unit area.
Irregular flower - a flower in which similar parts are unequal in size, form or extent of fusion as in e.g. Leguminosae (pea family). Often bilaterally symmetrical.
Isotropic - having the same property in all directions.