Love for rampancy

Post here the most violently spreading biomass factory plants you planted and love in your home garden.
I've got knotweed, both japanese and giant, clover, fertile comfrey and jerusalem artichoke. I also propagate cattails.

Living in a city struggling to remove knotweed not sure how I feel about that one. But going along the line of "scary invasives" that are biomass factories, I would have to say I have found Paulownia tomentosa (empress tree) to be quite fascinating. These trees grow in size so quickly and can appear quite impressive. I think there has been signs of potential in it's use of quickly collecting biomass in a controlled setting, and I prefer it over Ailanthus altissima (tree of heaven), which is just a STINKER.

Though Hibiscus cannabinu (kenaf) a plant I haven't encountered personally yet, seems like a real winner for quickly growing plant matter with uses beyond simply being "biomass", (i.e. paper and oils).

Fun topic!

My most rampant guild has to be my sunchoke/groundnut guild - which I very carefully contain in a raised bed between the street and sidewalk in front of my house. I harvest most of it every fall, and the next summer it gets way out of hand again. It's only May right now, and the groundnuts are already reaching for the linden nearby!

Well, really many plants that succeeded have become biomass producers, but one that I liked was the mint I planted on my greywater canal in 2018. Last summer in 2020 it was a nice stand of the stuff, much more than I could use, so before it could flower I cut it all and used it to mulch garden vegetables. It was a nice orderly mulch, nicely locked together so the wind wouldn't take it away (important in my location). Recently in May 2021, I was surprised to see the stand that I cut last summer doesn't seem to have sent up any shoots at all this year, although of course there's still mint popping up here and there nearby.

probably cup plant, Silphium perfoliatum. grows to 7 or 8 feet, though i’ll generally chop it back for chop’n’drop 3 or 4 times a season when it gets in the way or i need the green mulch. you can apparently press the seeds for an edible oil, but i haven’t gotten around to really collecting them in the needed quantity (late summer already being a busy time of year).

For us it's pumpkin! It took a long time to get going, even longer to start producing, but now it has naturalized and covers over 50 square meters after 3 years. It would be much larger but we (try to) keep it trained to stay out of the yard and the neighboring property or it would be hundreds of meters.

We get about 100 pumpkins a year, with the last pumpkins from one year lasting until the first pumpkins of the new year. All this from one plant. It covers most small weeds. Every week or two we spend maybe 5 minutes taking out a few tall weeds and re-directing growth. Not only do we get pumpkins but the flowers and shoot tips are edible too.