A clade is one complete branch of an evolutionary tree: an ancestor and every lineage descended from it. A group that leaves out some descendants, or mixes two branches, is not a clade. Biologists call a clade monophyletic.
The idea drives many recent name changes. The 2009 committee report on Psilocybe describes Deconica as the name for the “non-hallucinogenic clade” once DNA showed the old genus held two branches (Norvell, 2009). A 2026 study found the older limits of Strophariaceae and Hymenogastraceae were not monophyletic and proposed a new family, Agrocybaceae, for the clade holding Agrocybe and Psilocybe (Niskanen et al., 2026).
A 2024 genome study found two different gene orders in the psilocybin cluster that match a deep split inside Psilocybe (Bradshaw et al., 2024). In the laughing gym group, a 2020 DNA study by a Canadian-led team showed that several species had been sharing one name (Thorn et al., 2020). Clades are inferred from data, so a group called a clade today can be redrawn tomorrow.
Sources
- Norvell, 2009, Mycotaxon 110
- Niskanen et al., 2026 (PMC)
- Bradshaw et al., 2024, PNAS
- Thorn et al., 2020, Canadian Journal of Botany
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