Behind the stillness of desert landscapes, cacti appear to be changing in unexpected ways.
The cactus on your windowsill may not seem like a fast mover, but new research suggests cacti are remarkably quick when it comes to producing new species.
For years, biologists have argued that pollinators and specialized flowers are the main forces behind the rise of new plant species. Researchers at the University of Reading found a different pattern in cacti. Their results show that the key factor is not flower size or the animal doing the pollinating, but how quickly flower shape changes over time.
The team analyzed flower length data from more than 750 cactus species, with blooms ranging from just 2 mm (0.08 inches) to 37 cm (14.6 inches), a 185-fold difference. Even with that huge range, flower length was barely linked to how often a species gave rise to new ones. Instead, the strongest pattern was tied to speed of change. Cactus species with flowers evolving most rapidly were also the ones most likely to diversify, and that pattern appeared in both recent and long-term evolutionary history.
Published today in Biology Letters, the study pushes back on ideas that trace back to Charles Darwin. Based on his work on orchids, Darwin proposed that specialized flower forms helped drive the origin of new plant species.
What the researchers found
Jamie Thompson, lead author at the University of Reading, said: “People may think of cacti as tough, slow-growing plants, but our research shows that the cactus family is one of the fastest-evolving plant groups on Earth. Knowing how fast cacti evolve reveals that deserts, often seen as harsh and unchanging, are actually hotbeds of rapid natural change.
“We expected cacti with longer, more specialised flowers to be the ones creating the most new species. Instead, flower size made almost no difference. What matters is how quickly flowers change shape. Cacti whose flowers evolve rapidly are far more likely to split into new species than those whose flowers stay the same, however elaborate they are.
“This result has real implications for conservation. Since flower evolution has helped generate cactus species over millions of years, evolutionary pace should become part of conservation efforts. Although being able to rapidly evolve does not guarantee resilience, especially as the planet is changing faster than most cacti can keep up, it could help predict which species need the most help. Rather than searching for a single trait that predicts which cacti are most at risk, conservationists may need to look at how fast a species is evolving instead.”
Mapping the cactus family tree
The cactus family includes about 1,850 species and ranks among the fastest-expanding plant groups on Earth. Over the past 20 to 35 million years, it has spread across the Americas.
The study was supported by a new Open Access database called CactEcoDB. It was created by lead author Jamie Thompson and developed with ten coauthors from three continents, including six from the University of Reading. Published in Nature Scientific Data, the database combines seven years of work on cactus traits, habitats, and evolutionary relationships. With nearly one-third of cacti threatened with extinction, it gives scientists around the world a shared resource to study their biodiversity, conservation, and future under climate change for the first time.
References:
‘”Faster speciating cacti have faster evolving flowers ” by Jamie B. Thompson and Chris Venditti, 18 March 2026, Biology Letters.
DOI: 10.1098/rsbl.2025.0834
“CactEcoDB: Trait, spatial, environmental, phylogenetic and diversification data for the cactus family” by Jamie B. Thompson, Catherine Martinez, Jorge Avaria-Llautureo, Santiago Ramírez-Barahona, Gerardo Manzanarez-Villasana, Alastair Culham, Andrew Gdaniec, George Ryan, Chris Venditti, Georgia Keeling and Nicholas K. Priest, 7 March 2026, Scientific Data.
DOI: 10.1038/s41597-026-06936-7
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.