Ferns are the second-most successful clade of vascular plants, outnumbered only by their flowering kin. Yet genomic resources for the group have remained scarce, with no whole genome sequences for any of the 10,000 or so homosporous ferns—species with only one kind of spore—that account for more than 99 percent of fern diversity. That changed this year with the publication of three fern genomes in Nature Plants.
Researchers have long struggled to construct fern genomes due to their immense size and complexity. In general, the plants boast genomes that are 12 Gb long on average—larger than most flowering plants and nearly four times the length of the human genome. And these massive genomes are split into dozens of chromosomes. For instance, it’s estimated that the adder’s-tongue fern (Ophioglossum reticulatum) has 720 pairs of chromosomes. While ferns in general average about 40 pairs, that still considerably exceeds our mere 23.
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