Arabis pycnocarpa M. Hopkins. Slender Rockcress. Phen: May-Jun. Hab: Thin soils near outcrops of calcareous soils. Dist: QC west to AK, south to e. and sw. PA (Rhoads & Block 2007), AR, and AZ, primarily west of the Blue Ridge. Reports of this taxon from GA (Fernald 1950, Kartesz 1999, Hopkins 1937) are based on material collected by A.W. Chapman near Rome, and later described as Arabis georgiana. See discussion under A. adpressipilis.

Origin/Endemic status: Native

Taxonomy Comments: See Al-Shehbaz (2017) for discussion of the rationale for treating A. pycnocarpa and A. adpressipilis at species rank and also as distinct at species rank from the European A. hirsuta.

Synonymy: = K4, Al-Shehbaz (2017); = Arabis hirsuta (L.) Scop. var. pycnocarpa (M.Hopkins) Rollins – C, F, G, GrPl, Pa, Al-Shehbaz (1988a), Rollins (1993); = Arabis pycnocarpa M.Hopkins var. pycnocarpa – FNA7, Il, K3, Mi, NE, NY; = Arabis pycnocarpa M.Hopkins var. typica – Hopkins (1937); < Arabis hirsuta (L.) Scop. – S13; < Arabis hirsuta (L.) Scop. var. pycnocarpa (M.Hopkins) Rollins – K1

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Wetland Indicator Status:

• Eastern Mountains and Piedmont: FACU
• Great Plains: FACU
• Midwest: FACU
• Northcentral & Northeast: FACU

Heliophily: 6