A panicle is a compound raceme, a loose, much-branched indeterminate inflorescence with pedicellate flowers (and fruit) attached along the secondary branches (in other words, a branched cluster of flowers in which the branches are racemes).
This type of inflorescence is largely characteristic of grasses like oat and crabgrass[1], as well as other plants such as pistachio and mamoncillo. Botanists use the term paniculate in two ways: "having a true panicle inflorescence" as well as "having an inflorescence with the form but not necessarily the structure of a panicle".
A corymb is similar to a panicle with the same branching structure, but with the lower flowers having longer stems, thus giving a flattish top superficially resembling an umbel. Many species in the Maloideae, such as hawthorns and rowans, produce their flowers in corymbs.
A thyrse is a compact panicle having an obscured main axis and cymose subaxes, making its paniculate nature hard to discern. Many Ceanothus species have thyrsiform inflorescences, notably Ceanothus thyrsiflorus.