U

U-29: This World War I German submarine was the venue for most of the action in H.P. Lovecraft's short story "The Temple." There was, in fact, a German Imperial Navy submarine with this name active during the Great War, but there is no indication that Lovecraft based his vessel on the historic submarine.

For one thing, the U-29 is unequivocally known to have been sunk early in the war, on March 18, 1915, when it was struck by the battleship HMS Dreadnought (the only submarine known to have ever had such a dubious distinction). It is certainly possible that Lovecraft's submarine had the same characteristics as the U-29, a U-27-type vessel (pictured here), which was a diesel-powered torpedo attack craft that had a crew of 35 and was armed with a 105 mm deck gun.

upas tree: An actual sort of flora, the Antiaris toxicaria, that H.P. Lovecraft mentions in the prose poem "Memory": "In the valley of Nis the accursed waning moon shines thinly, tearing a path for its light with feeble horns through the lethal foliage of a great upas-tree." The upas tree is native to savannas and coastal plateaus in parts of Africa, Asia, and the South Pacific and the sap from its leaves and bark is used by native peoples to manufacture a deadly, heart-stopping poison for spears and arrows. It has a thick canopy of long, wide leaves, bears small edible red or purple fruit, and can grow to heights of greater than 100 feet.