According to observations of naturalists and beekeepers.
Where are you?
Park willow occurs in the middle and southern Rocky Mountain region from Wyoming to New Mexico.
This plant is present in at least 5 states/provinces in this country.
Park willow is a native, erect shrub 3 to 12 feet (1.5-4 m) tall, and usually forming dense clumps. The trunk of park willow is smooth or slightly cracked. The wood is fine-grained and soft and has no sapwood-heartwood line. Park willow has a remarkable characteristic of plasticity; its growth form adapts readily to a wide variety of habitats. Branching habit and foliage characteristics vary greatly depending on site conditions.
Park willow flowers in May, before the leaves appear, through July. The fruit ripens soon after flowering, followed by seed dispersal in early to midsummer.
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Asclepias tuberosa (aka: Butterflyweed, Butterfly Milkweed, Orange Milkweed, Pleurisy Root, Chigger Flower, Canada root, Fluxroot, Indian paintbrush, Indian posy, Orange root, Orange Swallow-wort, Tuber root, Yellow milkweed, White-root, Windroot, Butterfly love)
Citrullus lanatus (aka: Watermelon)