Pinguicula brendae: The Butterwort That Blushes Wet or Dry

A carnivorous plant that changes color with the weather has been described as new to science from a single cliff in Mexico. Botanists named the butterwort Pinguicula brendae after Brenda Muñoz-Vazquez, the researcher who first noticed its leaves were the wrong shade of purple. The plant lives on one north-facing limestone wall in a cloud forest in the state of Hidalgo, and nowhere else anyone has looked. Fewer than two hundred fifty mature plants exist, counted by hand. The species is already considered Critically Endangered, according to the study describing it.

A team of botanists was surveying butterworts in the montane cloud forest of San Bartolo Tutotepec when Muñoz-Vazquez stopped at a cliff wall and looked closer, botanical writer Alun Salt reported. Some of the plants on the rock were an unusual ruby-purple, unlike the green overwintering rosettes of the similar species Pinguicula crassifolia. The researchers walked the whole wall, tallying every plant they could reach. Then they asked people living nearby whether the plant grew anywhere else. The answer was no.

The formal description of Pinguicula brendae, published by Rodríguez-Ramírez, Shimai and Andrés-Hernández, sets out how the new plant differs from its relatives. Its overwintering rosettes are compact and ruby-colored, measuring 3 to 10 mm across. Each flower rises on a violet-brown stalk 38 to 60 mm tall, densely covered in tiny non-glandular hairs. The blossom itself is ruby with a white throat, and the curved spur at its back is 8.6 to 10.5 mm long. The plant grows at about 1985 m above sea level among mosses and ferns on vertical limestone, and the tally of mature individuals came to fewer than 250.

A color shift tied to wet and dry

Wet weather rewrites the plant's look. The ruby or purple foliage turns green when it rains, then blushes purple again as it dries. Other butterworts blush too, but the color switch on this wall is what tipped off the team: the plants were the wrong shade for what they were supposed to be. The species flowers from late February into early March, its ruby blossoms held well above the cliff face. The ruby winter rosettes are a seasonal costume, traded in for summer leaves that rarely stay green.

Butterworts earn their keep by eating. Their leaves are coated in sticky glands that trap small insects like flypaper and then digest them, a trick that lets the plants survive on bare rock where roots can do little more than hold on. The Hidalgo species, now formally Pinguicula brendae, joins a crowded Mexican roster of butterworts, but its combination of ruby overwintering rosettes and a violet-brown, hair-covered flower stalk sets it apart in the genus, the paper notes.

Named for the woman who spotted it

Plants named after women are uncommon enough that botanists take notice. The species name Pinguicula brendae honors Muñoz-Vazquez, the woman who discovered it, a distinction the botany press has singled out because eponyms so often go to mythological figures or relatives of the author. Salt wrote that the name could act as a lifeline, giving a plant almost nobody has heard of a fighting chance at formal protection. In taxonomy, a name is the handle that every later conservation listing grabs onto.

One cliff, and the threats to it

The paper provisionally assesses the species as Critically Endangered, citing an extremely small population and ongoing pressure from people and grazing animals. Goats roam the slopes and fire sweeps the dry forest, and a species that lives on one wall has no backup population. Local residents told the team the plant grows nowhere else, and fieldwork has not turned up a second site. Further surveys and seed collection would be the obvious next steps, but for now the entire known world of Pinguicula brendae is that single limestone face.

Cloud forests in this part of Mexico hold more endemic species than most botanists can survey in a season, and this butterwort went unnoticed until someone stopped at the right wall at the right time. The formal description now sits in the journal Phytotaxa, and the plant it describes is still exactly where it was found.