Tail-flower or raceme refers to a type of inflorescence where the flowers are arranged along a long, unbranched stem. It is typically found in plants such as the orchid, lily and pea families. There are a few different synonyms to describe this type of flower arrangement, such as spike, spadix, and panicle. A spike is a type of raceme where the flowers are attached directly to the main stem, while a spadix is a more condensed version of the raceme where the flowers are tightly packed on a fleshy stem. A panicle is similar to a raceme, but instead of a single unbranched stem, it has multiple branching stems with flower clusters.