Vascular Plants of North Carolina
Account for Spreading Rockcress - Arabis patens   Sullivant
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Section 6 » Order Capparales » Family Brassicaceae
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AuthorSullivant
DistributionFound only at scattered montane sites in the central and southern mountains, though this is a Northern species.

This is an uncommon Eastern species, ranging from PA and IN south to central AL and eastern MS.
AbundanceFound at a handful of sites in the Hot Springs portion of Madison County, but found only at a few other sites, in Swain and Rutherford counties. Very rare in the mountains as a whole. This is a Significantly Rare species.
HabitatThis is a rock based species, limited to high pH soils in NC. The sites in Madison County are calcareous, whereas ones in other counties are over mafic rocks -- marble and amphibolite. It grows in thin soil around the margins of such outcrops, as well as in cracks and crevices in cliffs, rocky summits, and other similar places.
See also Habitat Account for General Montane Basic Barrens and Glades
PhenologyBlooms in May and June, and fruits from June to August.
IdentificationThis species has erect branches (usually more than one from the base) that grow to about 1.5' tall. The stem and leaves are quite hairy. The scattered, alternate stem leaves are lanceolate to ovate, about 1.5" long and 1/3 as wide, with a rounded, generally clasping base; lower leaves are usually somewhat serrate on the margins. The upper several inches of the branches contain the racemes of white flowers, each with 4 petals and spread of about 1/2-2/3" across. The siliques are very narrow but flat, about 2-3" long, ascending or spreading, but not stiffly erect as in A. adpressipilis. One other native and rare mustard can grow with or near it -- Draba ramosissima -- but that species is somewhat sprawling or mat-forming, sending up numerous but much shorter (to about 6-9" tall) flowering stems, and has small branches from the upper stem; the siliques are twisted. Both are striking with numerous white flowers, but the Arabis is moderately tall and somewhat elegant, with no basal rosette; the Draba is "clumpier" with numerous and much shorter stems, and basal leaves that are short and pinnately divided.
Taxonomic CommentsNone

Other Common Name(s)None
State RankS1
Global RankG3
State StatusSR-T
US Status
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