As I speculated in my recent blog on Insights into Nitrogen Fixation from Higher Order Taxonomy, there is in fact at least one group of nitrogen fixers in the Cucurbitales order. This was the only standout order in its lineage without a Rhizobia- or Frankia-partnering nitrogen fixer.
The blog was reprinted on the lovely Permaculture Research Institute website, my favorite source for online permaculture news and articles. One commentator pointed out that Coriaria, the only genus in the Coriariaceae, and located in the Cucurbitales, fixes nitrogen.
I’m very glad to hear this and hope that other folks will point out other genera and families I’ve missed, proving or disproving my hypothesis.
Coriaria is an interesting genus, with a wide but spotty distribution in warm regions. Some have edible fruit and poisonous seeds. Apparently among the few native nitrogen fixers of New Zealand.
Coriaria myrtifolia, photo by Michael Wolf via Wikimedia Commons.