According to observations of naturalists and beekeepers.
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Hyssop is a perennial plant that is native to the Mediterranean region and has been imported and naturalized in the US and Canada. It grows along roadsides and is sometimes found as a garden herb. Hyssop is quite similar in appearance to other members of the mint family. Its volatile oil possesses a highly aromatic camphor-like smell.
It should be noted that there are a number of other common plants found in North America that go by a variation of the name "hyssop." These include giant hyssop (Agastache sp.), hedge hyssop (Gratiola officinalis), and water hyssop (Bacopa sp.). None of these plants are members of the genus Hyssopus.
This plant is present in at least 17 states/provinces in this country.
Hyssop is a brightly colored shrub or subshrub that ranges from 30 to 60 cm (12 to 24 in) in height. The stem is woody at the base, from which grows a number of upright branches. Its leaves are lanceolate, dark green, and from 2 to 2.5 cm (0.79 to 0.98 in) long.
During the summer, hyssop produces pink, blue, or, more rarely, white fragrant flowers. These give rise to small oblong achenes.
The plant blooms from July to September. The fruits ripen in August.
The plant is commonly used by beekeepers to produce nectar from which Western Honey Bees make a rich and aromatic honey.
Cercis canadensis (aka: Eastern redbud, Redbud, Cersis Reniformis)
Acer saccharinum (aka: Silver maple, Soft maple)
Ulmus americana (aka: American elm, White elm, Water elm, Soft elm, Florida elm)
Salix nigra (aka: Black willow, Swamp willow, Southwestern black willow, Gulf black willow, Scythe-leaved willow)
Pyrus communis (aka: European pear, Common pear)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Salix discolor (aka: Pussy willow, American pussy willow, Glaucous willow, Large pussy willow)