| Author | (L.) Dumortier | |
| Distribution | Throughout the Coastal Plain and Piedmont, and present over most of the Mountains. May well occur in all 100 counties.
This is a widespread species of eastern North America, found from eastern Canada south to the Gulf of Mexico. It is rather scarce in the mountains and westward, but is found in practically every county in the Coastal Plain and Piedmont provinces. | |
| Abundance | Very common to abundant over nearly all of the Coastal Plain and Piedmont, but not common in the far eastern Coastal Plain, except the Outer Banks. Uncommon in the central and southern Mountains. | |
| Habitat | This is a ubiquitous species of weedy places, especially abundant in fallow fields, the first year after being left fallow. It also grows on roadsides, overgrown fields, powerline clearings, around rock outcrops, and other sunny and grassy places. Perhaps it was originally a species of outcrop margins, but it is now considered a "native weed". | |
| Phenology | Blooms mostly in spring, from March to May, rarely into summer perhaps in areas where mowed recently. Fruits shortly after flowering. | |
| Identification | This species is so familiar it needs no introduction. It has a slender, unbranched stem to about 1 foot tall. Though there are a few small basal leaves that lie along the ground, in general it has alternate, scattered, and small linear leaves up the stem, with each leaf only about 2/3-inch long and very narrow, mainly erect to ascending. At the top of the stem is the short raceme, of often 10 or more flowers, each flower like a miniature snapdragon, light (Carolina) blue in color, with white in the center. The lips extend past the upper petals, and there is a narrow spur in back; the flower is roughly 1/2-inch long, including the spur. Many a fallow field in the Piedmont and Coastal Plain glows light blue with thousands upon thousands of individuals of this species. In some areas, these fields are also rosy pink to reddish and blue in color, with one or two species of Rumex also growing with it, adding in the reddish color. | |
| Taxonomic Comments | Though long known as Linaria canadensis, it was transferred to the genus Nuttallanthus -- as N. canadensis -- by some references. Weakley (2018) retains it in Linaria.
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| Other Common Name(s) | Blue Toadflax, Common Toadflax, Oldfield Toadflax. Often simply just called "Toadflax".
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| State Rank | S5 | |
| Global Rank | G5 | |
| State Status | | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
