While encyclopedias direct readers of the "upas tree" entry to mulberry, the Bohun Upas tree was supposed to be a poisonous tree growing near Cathay, according to the first medieval Europeans there. It was said to produce narcotic and toxic fumes which killed plants and animals for miles around; Malaysians supposedly executed prisoners by tying them to its trunk. The actual bausor tree, which did grow there, produced a poisonous latex used by native Malaysians on their arrow tips.
The myth inspired a poem by the Russian Aleksandr Pushkin in 1830; the title is also translated as "The Poison Tree," "Anchar, the Poison Tree," or simply "The Upas." One translation follows:
Deep in the desert's misery,
far in the fury of the sand,
there stands the awesome Upas Tree
lone watchman of a lifeless land.
The wilderness, a world of thirst,
in wrath engendered it and filled
its every root, every accursed
grey leafstalk with a sap that killed.
Dissolving in the midday sun
the poison oozes through its bark,
and freezing when the day is done
gleams thick and gem-like in the dark.
No bird flies near, no tiger creeps;
alone the whirlwind, wild and black,
assails the tree of death and sweeps
away with death upon its back.
And though some roving cloud may stain
with glancing drops those leaden leaves,
the dripping of a poisoned rain
is all the burning sand receives.
But man sent man with one proud look
towards the tree, and he was gone,
the humble one, and there he took
the poison and returned at dawn.
He brought the deadly gum; with it
he brought some leaves, a withered bough,
while rivulets of icy sweat
ran slowly down his livid brow.
He came, he fell upon a mat,
and reaping a poor slave's reward,
died near the painted hut where sat
his now unconquerable lord.
The king, he soaked his arrows true
in poison, and beyond the plains
dispatched those messengers and slew
his neighbors in their own domains.