gorse, a plant with "blood" & mechanically-activated pollen shotguns
Gorse is so cool. You may know it as Scotch Broom, Furze, Whin ... Ulex is the genus.
Ulex europaeus Gorse has bright-yellow flowers. The flowers are quite tightly closed. A suitably strong bee will go to an unactivated (closed) flower and press up on one petal and down on another, to try and reach the juicy bits. Pulling these petals away from one another causes a mechanical release within the flower which basically shotguns the bee right in the face with pollen. If you find an unactivated gorse flower, which can be really hard to do because bees are little busybodies, you can (gently) activate the flower by finding the innermost petals and pressing them apart with your fingertips.
but, as alluded to in the title, it's more than just the pollen-shotgun that's a Weird Gorse Thing. Gorse has haemoglobin, which is a protein making up the large majority of human blood. Not all animals have haemoglobin, but a whole lot do, and a plant having haemoglobin feels a bit weird because of that.
It’s convergent evolution here, and it's used for the same purpose we use haemoglobin: oxygen transport. Gorse brings oxygen to the nitrogen fixing bacteria at its roots.
If you're not familiar with the term "nitrogen fixing", nitrogen is a super important element for life (used to make proteins, DNA, so on...!) but the way it occurs in the atmosphere (dinitrogen, N2) is two nitrogens bonded together very strongly, strongly enough that most critters can't break it to get access to the nitrogen they need. Some organisms, though, are "nitrogen fixers", specializing in converting dinitrogen into things like ammonia which are more accessible for life. Gorse is a legume, many of which have warty-looking roots, with the bumps serving as little houses for nitrogen-fixing bacteria. The bacteria gets oxygen (and other stuff) from the gorse, and in exchange the gorse gets nitrogen right from the source.
Nitrogen-fixing plants (plants w/ this kind of relationship with bacteria) are really important in agriculture. They can be grown mixed in with other plants (polyculture/intercropping), or grown in an alternating pattern with other plants in the same field over a long time (crop rotation), and dead legume plants can be left on the ground for other life to access their nitrogen. but: Probably don’t use gorse for that, it’s far too aggressive.
...
That is a problem with gorse, it’s tenacious. In the past in its native range it would be healthily suppressed by human use. Its flowers can be brewed into alcohol and its thorny branches would be crushed down into nutritional animal food. Across the UK, there are old millstones left behind, remnants of time spent crushing whin-shoots under the stones to flatten the spikes enough for animals to eat it1. Now humans don’t do that, & it grows unchecked.
its growth results in gorse outcompeting rare ecosystems that would normally be too disturbed (by harvesting, being walked on, etc) for gorse to grow. In areas around the world, to different degrees, humans have been too protective ... usually, there is a degree of disturbance in the environment, from animals walking around and grazing, from wildfire, so on. In some cases, we disturbed a place way too much, and seeing how it endangered many species, we reflexively put an embargo on all disturbances. Biomes naturally go through "succession", where certain conditions allow certain things to live there, and those things alter the conditions enough that eventually that new things can grow. Marram grass grows well in loose sand, but when it grows it stabilizes the sand with its stems and roots, meaning that the sand is no longer too loose for other plants to move in and take over. That sort of thing. Disturbance can pull succession backwards2, for example, tearing up a bunch of plants back to bare sand, so we're back at the loose-sand environment. When we stopped disturbance entirely, succession continued, the species that live in the earlier stages getting pushed out by new ones ... getting swallowed by a wave of gorse. Now, we're having to go in with backhoes to tear the plants off the top of sandy ground, carving out a place for those early-stage creatures to live in. The fact gorse is aggressive & spiky (not pleasant to try and remove!) doesn't make this easier.
and also it’s invasive in places like New Zealand where Scottish colonizers brought it over because they were homesick , allegedly. You can imagine that the problems around gorse's aggression and toughness don't make dealing with invasive gorse very easy.
There is another problem with so much gorse. Gorse is a "pyrophile" plant: it has adaptations that let it bounce back quickly after a fire, in that its tough seedpods are opened by the heat of fire so it's the first plant to get its foot back in the door. It is highly flammable as well, which makes sense from the perspective that if there isn't enough fire then other plants could take over the gorse. So when it's growing unchecked and/or invasively, it is a huge fire hazard. in soggy places like the UK, that's not such a problem, but when it's invasive in a dry climate ... uh oh!
...
I do love it though, I'm in its native range and I like to get scratched up by it when exploring. I do wish we still used it for things like brewing and livestock feed, especially since it grows well in poor-quality soil that wouldn't be useful for food crops (the ideal use-case for animal agriculture!). but we have bigger fish to fry from a conservation standpoint, at least for now.
thanks for reading!🪱🦀
Atom feed ; RSS feed
...
1 ) Bishop, P. Whin Millstones in Baldernock, Western Central Belt.
2 ) Brunbjerg, A. K., et al. Disturbance drives phylogenetic community structure in coastal dune vegetation. Journal of Vegetation Science, 2012 23(6):1082-1094.