Vascular Plants of North Carolina
Account for Hoary Frostweed - Crocanthemum bicknellii   (Fernald) Janchen
Members of Cistaceae:
Members of Crocanthemum with account distribution info or public map:
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Section 6 » Family Cistaceae
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Author(Fernald) Janchen
DistributionStrictly in the Mountains, and mainly in the southern counties.

This Midwestern and Northern species ranges from ME and ND, south to western NC and OK.
AbundanceVery rare, with only four of the eight records in the NCNHP database still considered to be current. Probably has declined over the past few decades, with few recent discoveries. This is a State Species Concern species.
HabitatThis is a species of the higher elevations in NC. It grows mostly in sunny places and dry to mesic soils, such as on rocky summits, grassy balds, glades and barrens, and open woodlands.
PhenologyBlooms in June and July and fruits from August to October.
IdentificationThis is a slender and erect herb, with a few branches, growing to about 8-20 inches tall, typically about 1 foot tall. It has 10-20 alternate stem leaves, typically ascending, narrowly elliptic to oblanceolate, about 1-inch long and 1/4-inch wide, with entire margins. The plants are quite pubescent overall, with the leaves tomentose below. The flowers (those with petals) grow in small terminal clusters, usually 5-12 such flowers. Each is a typical one for the genus, with 5 yellow petals, and a spread of about 4/5-inch across. This species must be separated from the also-rare H. propinquum, which also grows at high elevations in similar habitats. That species grows only to an average height of 10-30 cm (4-12 inches), averaging about 8 inches tall. Also, that species has a scattered growth as opposed to clustered in H. bicknellii. Among other separation characters, the base of the leaf in H. bicknellii is broadly cuneate, whereas that in H. propinquum is narrowly cuneate to attenuate. You may need to turn to one or more keys to be sure which is which, but either is a good find.
Taxonomic CommentsNone

All NC species of Crocanthemum were formerly placed in the genus Helianthemum.
Other Common Name(s)Plains Sunrose, Plains Frostweed
State RankS1
Global RankG5
State StatusSC-V
US Status
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