gamosepalous

Gamosepalous describes a floral calyx in which the sepals are united (connate) by their bases, forming a tube, cup, or ring around the developing bud. The term comes from Greek roots meaning “united sepals.” It is used to distinguish calyces with fused sepals from those with sepals that are free, or schizocarpous, referred to as disepalous.

The degree of fusion in gamosepalous species can vary. In some taxa the sepals are completely fused along most or all of their length, producing a tubular calyx that encloses the corolla or bud. In others, fusion is limited to the bases, resulting in a shallow cup or inflated calyx while the apices remain free. The presence of a gamosepalous calyx is a characteristic that can help in the identification and description of species or genera, often alongside other floral traits such as corolla form and leaf arrangement.

In taxonomy and systematic botany, gamosepalousness is treated as a morphological character. While it can aid in distinguishing groups, it is one of many traits and may be subject to variation within lineages or convergent evolution in unrelated taxa. The term is commonly paired with its opposite, disepalous, to contrast fused versus free sepals.

See also: gamopetalous, disepalous, connate.