What's the noun for willowiest? Here's the word you're looking for.
willow
Any of various deciduoustrees or shrubs in the genus Salix, in the willow family Salicaceae, found primarily on moist soils in cooler zones in the northern hemisphere.
“This successful woodenware and willowware merchant was a dedicated philanthropist.”
“Not unless there's a mortgage company that takes down payments in sixties Superhero comic books and Great Aunt Martha's willowware.”
“They make a nice antidote to the Anglophobia of the breakfast rooms, where a persuasive case is made for polished mahogany, willowware and crustless toast.”