Inflorescence : the arrangement of flowers on the floral axis : a flower - cluster. 

Imbricate: overlapping; usually of arrangement of sepals and petals. 

Imparipinnate: a condition in a compound leaf with an odd terminal leaf-let. 

Induplicate: with edges folded inwards. 

Indusiate: with a protective membrane on the sori in ferns. 

Inferior: position of a floral part at a lower level (usually of ovary). 

Involucre: a ring of bracts surrounding a single flower or an inflorescence. 

Involute: rolled inwards along both margins.