The kidney stone hydrangea

Species name: Hydrangea arborescens

Common name: Smooth hydrangea, wild hydrangea

Location: Ontario

This species of hydrangea is native to eastern North America, but just slightly further south from where I am. The native range stretches from New York to Florida, but the plant was spread many, many generations ago by early settlers to North America because of its showy flowers in the late spring and early summer. The flowers, for the most part, are sterile; only a few in a bunch have stamens and stigmas. This seems to be a trade-off of showy flower production: the more flowers the plant produces that are able to be fertilized, the more the plant has to invest in resources for seed production. Here's the part where it's a trade-off; more resources into seed production means less resources into growth and general maintenance. That being said, almost all of the flowers that are sexual flowers do produce seed, so this plant is incredibly effective at reproducing that way. My over-the-back-fence neighbour has this plant growing in their back yard, so I couldn't get as close to the flowers as I wanted to show the difference between fertile and sterile flowers.

Historically this plant was used medicinally, but today this use has all but been forgotten except in historical texts. Ancient Native North Americans used this plant to treat problems with the kidneys and bladder, most likely kidney or bladder stones. They then taught this practice to early settlers of North America, who likely brought the practice back to Europe. How exactly this plant helped kidney or bladder stones to my knowledge is unknown; it could merely be the placebo effect where drinking a warm liquid seems to ease the intense pain of trying to pass a stone. Perhaps there is actually some molecule in the plant extract that helps break down stones; to my knowledge no one has truly done a clinical trial to observe the effects of hydrangea extract, nor has anyone done a full chemical analysis to determine what exactly it is in the extract that might be useful to the body. There was one medical doctor in the 1850s that noted anecdotally that up to 120 calculi (very, very small deposits on the inside of the kidney or bladder that can build and dislodge to become kidney/bladder stones) were passed by a single person taking hydrangea root honey, but you have to wonder considering the technology of 1850!