Vascular Plants of North Carolina
Account for Grooved Yellow Flax - Linum sulcatum   Riddell
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Section 6 » Order Linales » Family Linaceae
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AuthorRiddell
DistributionKnown only from a single county (Granville) in the northern Piedmont [specimen at DUKE and mapped by Rogers (1963)]. A specimen at NCU for Buncombe County in the Mountains is misidentified, as a specimen at BAYLU from Dare County. NCNHP reports it as historical from Durham County, but we have not seen documentation.

This is a mainly Midwestern species, ranging eastward to NH and western FL. Most Atlantic Coast states have only a few records each.
AbundanceOf historical occurrence, with a single collection -- August 11, 1951. The species has been repeatedly surveyed for at the handful of mafic glades in Granville County and neighboring Durham County, over the past few decades, without success. In fact, with all of the VA records being in the Mountains, there are no nearby Piedmont populations from which the species might re-colonize NC. This is a Special Concern - Historical species.
HabitatThis is a "prairie plant" -- growing on dry, high pH soil, over mafic, ultramafic, or calcareous rocks. It grows in mafic glades and barrens, dry wooded borders and openings, and other similar places.
PhenologyBlooms and fruits from May to August.
IdentificationThe Linum species are quite difficult to identify, especially as many of the former varieties and subspecies have now been elevated to full species. All are erect herbs to 1-2 feet tall, with slender branches that are usually ascending, small and narrow leaves, and numerous scattered small yellow flowers (with 5 petals) along the upper portions of the branches. This very rare species, historical now in NC, can be separated from all others by having "leaves with 2 red or brown stipular glands flanking the attachment to the stem" (Weakley 2018). The other species lack such colored glands at the leaf bases. Also, this species has the "Inner and outer sepals all very conspicuously glandular-toothed", as opposed to "Outer sepals entire .." (Weakley 2018). To identify this plant, you may need a hand lens in the field, to see the dark glands.
Taxonomic CommentsNone

Website editors have received much help in species boundaries and in identification from Rogers (1963, 1984).
Other Common Name(s)Grooved Flax, Furrowed Flax
State RankSH
Global RankG5
State StatusSC-H
US Status
USACE-agcp
USACE-emp
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B.A. SorriePhoto taken 2000, prairie in Jackson County, IA. Photo_non_NCPhoto_non_NC
B.A. SorriePhoto taken 1986, Soldiers Delight serpentine area, MD. Photo_non_NCPhoto_non_NC
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