Poplar
The poplar in the UPDV is a leafy tree that turns up at two opposite ends of Israel's life — once as a peeled rod in Jacob's flock-breeding scheme, once as a shade-giver beneath which the high-place worship of Hosea's day is conducted.
Jacob's Rods
When Jacob is engineering his wages out of Laban's flocks, he chooses the wood deliberately: "And Jacob took for himself rods of fresh poplar, and of the almond and of the plane-tree. And peeled white streaks in them, and made the white appear which was in the rods" (Gen 30:37). The poplar heads the list of three rod-woods used to expose pale stripes against dark bark.
Under Poplars at the High Places
Hosea pairs the poplar with the trees of forbidden worship: "They sacrifice on the tops of the mountains, and burn incense on the hills, under oaks and poplars and terebinths, because their shadow is good: therefore your⁺ daughters go whoring, and your⁺ brides commit adultery" (Hos 4:13). The grouping with oaks and terebinths, and the rationale "their shadow is good," fix the poplar in the picture of hilltop sacrifice the prophet condemns.