It's an active area of research but there's no consensus on why this happens other than hand wavy evolutionary biology stuff. The most interesting mechanism is paleopolyploidy [1] where the whole genome of the organism is doubled due to hybridization or DNA replication errors and from that point on the duplicates start diverging. It has occurred at least once in most flowering plants and it must have happened several times with this fern. Normally after this kind of event, the genome is paired down and duplicate genes are "silenced" in a process called diploidization [2] but if there are a bunch of transposable element, they might differentiate the copies enough to keep them before the process completes.

[1] https://en.wikipedia.org/wiki/Paleopolyploidy

[2] https://en.wikipedia.org/wiki/Diploidization

Interestingly, warm-blooded animals (including humans!) tend to have simple genomes compared to cold-blooded ones or similar complexity. It's just much easier to get repeatable results during development when you can do all the trickiest parts at fixed temperature, a human can use a single gene to achieve what a frog needs half a dozen for.

Plants are tolerant of gene duplication, possibly related to the fact that their stem cells are permanently active (which is why you can take a branch tip and get it to grow into a whole plant, quite unlike the efforts needed to clone Dolly the sheep). Their development is thus remarkably plastic (so you can get trees at the snowline that look like small shrubs, while the same species grows into tall straight trees a few thousand feet lower). In contrast, gene duplication at a large scale in any animal would probably fundamentally mess up body plan development in non-survivable ways.

Plants might be under active selection for gene duplication since it does allow rapid evolution and facilitates spread into new environments:

Evolution of Gene Duplication in Plants (2016) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4972278/

We touched on polyploidy in genetics of course but I don't recall anything that was particularly salient insofar as resistances. In humans xploidy typically results in either excessive protein expression or compromised (≤50%) protein expression - in many cases this is fatal or seriously damaging in terms of fertility/development. There are exceptions, for instance the mammalian liver has polyploidal cells.

But plants are way different in terms of habit, think about evolving to sit in the same place for a hundred years...

These for example could have epigenetic crosstalk between their environment (epiphytic nature) and their hosts. E.g. a special chromosome for birch vs oak. Or drought vs monsoon. Given the endpoint of the species is purportedly 350mn years it stands to reason that a highly specialized and nuanced system of regulatory pathways may have emerged. Sequence data and genomics would be revelatory.

It wouldn't surprise me if there was specialized information per-host which was regulated by signal produced by the host, I think this would explain redundancy pretty well. Different epigenetic pathways operating on different x¹ chromosomes yielding differential response to discrete small molecules/proteins/hormones produced by host species which prove beneficial in the looong run. This could have a whole cascade of effects or just subtle SNP differences which yield fitness enhancements. Essentially each one being a subroutine for each host case producing local optimums.

But I'm just a scrubby undergrad so with a grain of salt. There's probably many other more reasonable explanations, it's biology, biology seeks to find exceptions to every rule by its nature.

Weird, since ferns’ fractal growth plan lends itself so well to simple recursion.

Maybe most of the genome is just a long comment explaining why they can’t use recursion.

Until a better story emerges, I'm imagining that fern mode is just what we see when it is dormant. Perhaps if we prod it in the right way it will wake up and show us its true colors.

This is like template metaprogramming :)

You're confusing the difference between macros and functions, only functions fully avoid duplication (except when they are inlined!)

Macros are expanded into text by the preprocessor. Templates are expanded by the compiler instead.

If we count evolution as amount of genes evolved in the genotype, onions are five times more evolved than us.

But lot of this consists into redundant copies of the same information and another big chunk is included garbage borrowed from attackers. This fern could have a lot of things trying to finish it, an a lot of time to think about the problem. And of course could be also an hybrid or an hybrid of several hybrids.

Plants are considerably simpler than animals so they tolerate a lot more genetic nonsense. Crazy things like duplications which would simply result in non viable animals most often don’t have nearly the harmful effects in some plants so they survive and aren’t nearly so aggressively pruned out by evolution.

It makes sense to me. If you can't move (or can't move much) there'll be less variety in what you can take in, and some simple strategies for dealing with stressor don't work, so there is more need to be able to synthesise a wider variety of things.

one theory is it is anti-viral. can't infect a gene you can't find because it is a needle in haystack

Without plant based life, there are no humans, so we are technically using those genes.

Perhaps they need that code to deal with the extreme environmental changes day to day due to being in a fixed location.