Smallest terrestrial plant genome

No other plant on land has a smaller genome (an organism's total genetic material) than the carnivorous Genlisea tuberosa, a corkscrew plant endemic to Brazil. According to a study published in the journal Annals of Botany in December 2014, this plant has a mere 61 megabase pairs (or 61 million base pairs), which are the basic building blocks of DNA. The human genome, by contrast, is comprised of c. 3.2 billion base pairs.

This also means it has the smallest genome for an angiosperm (flowering plant).

A small genome is a common feature to several members of the corkscrew plant family (Genlisea), native to South America, Central America and Africa. These carnivorous plants use modified subterranean leaves (which bear a resemblance to roots owing to their lack of chlorophyll) to trap micro-organisms such as protozoans living in the soil. A tiny aperture (c. 400 micrometres in diameter) in the tip of the "root" allows the unwitting tiny creatures access but then backwards-facing hairs prevent it from leaving once it has ventured too far inside.

Prior to genetic analysis of corkscrew plants, the smallest-known plant genome (and indeed the first to ever be studied) was that of mouse-ear cress (Arabidopsis thaliana, part of the mustard family) found in Africa and Eurasia, with around 135 million base pairs. Nowadays, the title of smallest known genome for a plant overall often goes to the unicellular marine alga Ostreococcus tauri with a tiny genetic makeup of just 12.56 million base pairs, as documented in the journal Proceedings of the National Academy of Sciences on 1 August 2006. However while once classified under the kingdom Plantae (plants), algae are now placed in the Protista kingdom; while photosynthetic, they are not truly plants. The smallest eukaryotic genome belongs to Encephalitozoon intestinalis, a microsporidian (that is, a unicellular fungus or fungal ally) with a genome of only 2.6 Mbp (Fernandez et al., 2024).

Meanwhile, the largest plant genome (and indeed the largest known genome of any organism assessed to date) is that of the Tmesipteris oblanceolata fork fern of the Pacific territory of New Caledonia and nearby islands; it has a staggering 160.45 billion base pairs as reported in iScience on 31 May 2024.