The genus with the smallest known genome among flowering plants is Genlisea.
The record is associated especially with Genlisea tuberosa, a small carnivorous plant from Brazil. Its genome has been measured at about 61 megabase pairs, or roughly 61 million base pairs—remarkably compact for an angiosperm. That figure is why the genus is used as the answer rather than a larger, more familiar pitcher-plant genus such as Nepenthes.
Genlisea belongs to the bladderwort family Lentibulariaceae. Its unusual subterranean structures are modified leaves rather than true roots. These pale, rootlike organs form narrow traps that capture tiny organisms, including protozoans.
The record is easy to misstate as a claim about all plants or all living organisms. It concerns the smallest known genome reported for a flowering plant, and genome records can change as more species are sequenced. The genus is also notable for its rapid molecular evolution across nuclear, chloroplast, and mitochondrial genomes.