Mexican Sunflower is not a legume, but I've read on some websites that they can increase the nitrogen in the soil. But I've been unable to find a credible source of information stating that diversifolia has a symbiotic relationship with diazotrophs.
I have read that Mexican Sunflower is a nutrient accumulator. Does that mean that they just accumulate nitrogen from other nitrogen fixers? Or do they actually fix nitrogen?
Is Tithonia diversifolia (Mexican sunflower) a nitrogen fixer?