Do not confuse with unrelated
🇦🇺 Australian rainforest laurel tree Endiandra globosa
which is also sometimes called black walnut.
Part of
butternut/walnut genus Juglans
in
butternut/hickory/pecan/walnut family Juglandaceae
in
bayberry / beech / birch / oak / walnut order Fagales.
Native to 🇨🇦 🇺🇸 Canada and USA, east of the 🏔 Rocky Mountains.
🗺 Map by county (🇺🇸 USA-48),
🗺 map (North America, Central America), 
🗺 today + with climate change (eastern 🇺🇸 USA).
🏛🌰︎🌳︎ State nut tree of Missouri.
Uses by native peoples
(Ethnobotany database)
A 🪵 superdense hardwood, very durable, with a dark grain. In WWI, the wood from American walnut was highly valued for making airplane propellers and gunstocks. Its 🪵 wood is currently valued for furniture and cabinets.
Juglans hosts caterpillars of 130 species
of butterflies and moths, in some areas.
This plant is also known to be a host for (in areas where invasive)
🐝︎ spotted lanternfly (SLF) Lycorma delicatula.
This tree produces a
☠︎ toxic[?] substance juglone that prevents many plants from growing under or near them.
Our neighbors still cannot get 🍅︎ tomatoes to bear fruit in soil beneath their mature black walnut tree, after they cut it down!
✋︎ On the other hand, 🌾︎ turf grass lawn still seems to grow underneath.
Plants native to North America that are resistant to juglone (scroll down).
✋︎ On the third hand, back when my yard contained a walnut tree, before mowing or playing ⚽︎ football-soccer / 🥍 lacrosse
/ whatever, this author had to walk the lawn and kick any walnuts off to the side.