Berberis canadensis Mill.

Berberis canadensis Mill. View in CoL [ Berberidaceae ] American Barberry

This species was previously known from four counties in Alabama through historical collections (Jefferson County in 1944, Lee County in 1968, Shelby County in 1944, and Tuscaloosa County in 1933), so the present Bibb County collection marks the first collections of this rare S1 ( ALNHP 2023; Keener et al. 2023) taxon for Alabama in 55 years [Lee Co., 20 Apr 1968, Carr 75 (AUA)]. Many directed searches at each previously known collection site were unproductive in relocating the taxon.

The rarity of B. canadensis is often attributed to a widespread eradication program in the early 20th century due to its ability to vector the black stem rust, Puccinia graminis Pers. , a fungus that disastrously affects cereal crops ( Strausbaugh & Core 1978). These efforts resulted in the destruction of an estimated 150 million American barberry shrubs between the years 1935–1950 across its range ( Strausbaugh & Core 1978). However, southeastern United States populations of the species likely did not experience as severe eradication pressure due to the low survivability of black stem rust in the climate of the deeper South. Perhaps loss of primary fire-maintained woodlands has instead or also played a significant role in the decline of B. canadensis ( Hill 2003) .

Voucher Specimens: ALABAMA. Bibb Co.: Thin soils overlain on west facing Ketona Dolomite outcrop; small population of (possibly clonal) shrubs totaling ca. 300 stems; dried pedicels observed, 3 Jul 2020; with Echinacea purpurea (L.) Moench, Thalictrum amphibolum Greene , Myriopteris lanosa (Michx.) Grusz.& Windham , Clematis glaucophylla Small , under Juniperus virginiana L., 3 Jul 2020, Noah D. Yawn 53 & Alan Cressler (ALNHS 6942); 23 Jul 2020, T. Wayne Barger 5301 & Noah D.Yawn (ALNHS 6942).