According to observations of naturalists and beekeepers.
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This plant is present in at least 6 states/provinces in this country.
Richardson's willow is an erect, much-branched shrub usually forming dense clumps 3 to 6 feet (1-2 m) tall, sometimes to 15 feet (4.5 m). Young twigs are stout and densely hairy; older twigs are glabrous. The bark of Richardson's willow is smooth. Shrubs are composed of light wood that becomes brittle with age; a single trunk rarely survives 60 years. In silty loam containing much organic matter, the roots of Richardson's willow are numerous in the top 7.5 inches (19 cm) of soil, but become less abundant at 9 inches (23 cm). In the frozen ground, roots of Richardson's willow do not exceed 9 inches (23 cm), but as the ground thaws roots will grow up to 17 inches (43 cm) deep.
Richardson's willow flowers from May through July or August. The fruit ripens soon after flowering, followed by seed dispersal in early to midsummer.
Allium schoenoprasum (aka: Chives)
Brassica napus (aka: Rapeseed)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Chamaenerion angustifolium (aka: Fireweed, Great willowherb, Rosebay willowherb, Saint Anthony's Laurel, French-willow)
Agastache foeniculum (aka: Giant hyssop, Blue giant hyssop, Anise hyssop, Fragrant giant hyssop, Lavender giant hyssop)
Borago officinalis (aka: Borage, Starflower, Common borage, Cool-tankard, Tailwort)
Cirsium arvense (aka: Creeping Thistle, Canada thistle, Field thistle, California thistle, Lettuce from hell thistle, Corn thistle, Cursed thistle, Green thistle, Hard thistle, Perennial thistle, Prickly thistle, Small-flowered thistle, Way thistle, Stinger-needles)