imbricate

adjective

(L. imbricarus: tiled) Having parts overlapping each other like tiles or shingles on a roof. Overlapping, either vertically or spirally, where the lower piece covers the base of the next higher, or laterally, as in the aestivation of a calyx or corolla, where at least one piece must be wholly external and one internal. Lying lapped over each other in regular order. Of perianth parts, having the edges overlapping in the bud. Cf. valvate.