Sage flowers use a hinged lever to slap pollen onto bees
Push into a sage flower for nectar and a tiny lever swings down, dabbing pollen on your back. That trick defines Salvia, the biggest genus in the mint family, which now includes rosemary. DNA later revealed a surprise: the lever evolved separately at least twice, and the genus had been drawn wrong for nearly two centuries.
Salvia holds just under 1,000 species of shrubs, perennials and annuals, making it the largest genus in the Lamiaceae. Around 600 of them grow in Central and South America, about 250 in Central Asia and the Mediterranean, and some 90 in eastern Asia. The name comes from Latin salvus, meaning safe or healthy, and Pliny the Elder is the first writer known to describe a plant the Romans called salvia. English sage came by way of Old French sauge.
Where most of its relatives carry four stamens, Salvia has two. On each, the two pollen sacs sit at opposite ends of a long connecting arm that works as a lever. A visiting insect pushes the lower end and the upper, pollen-bearing end swings onto its back; when the visitor leaves, the lever springs back. Many species also carry glandular hairs that burst when brushed, releasing aromatic oils that deter grazing animals.
George Bentham wrote the first full account of the genus between 1832 and 1836. He admitted he probably ought to have split it into five or six genera, but decided renaming more than two hundred species was not worth it, and grouped it into twelve sections instead. More than 500 species have been found since. Gabriel Alziar's 1989 world catalogue trimmed as many as 2,000 names down to fewer than 700 distinct species and subspecies.
Molecular work showed Salvia was not one lineage but three clades, each evolving the lever independently, an elegant case of convergent evolution. Walker and Sytsma worked this out in 2007. Keeping the genus intact meant absorbing five small genera, among them Rosmarinus and Perovskia, which Drew and colleagues proposed in 2017; rosemary is now Salvia rosmarinus. Chia, grown for its seeds, belongs here too, and one Lebanese endemic is named after the singer Fairuz.
Source: Salvia
