Asplenium ruta-muraria Linnaeus var. cryptolepis (Fernald) Wherry. American Wall-rue. Phen: May-Oct. Hab: Moist to dry outcrops of calcareous sedimentary or metamorphic rocks, such as limestone, dolostone, or marble, at low to moderate elevations. Dist: A. ruta-muraria is a circumboreal species of Europe, Asia, and North America; in North America it ranges as var. cryptolepis from VT, s. ON and n. MI south to n. NJ, w. NC, nw. GA (Jones & Coile 1988), n. AL, TN, and AR (Peck 2011).

Origin/Endemic status: Native

Other Comments: Var. ohionis is very likely only a form. The relationship of North American A. ruta-muraria (here distinguished as var. cryptolepis), a tetraploid, to the diploid and tetraploid taxa of the A. ruta-muraria complex present in Europe and e. Asia is uncertain. Given the prevalence of allopolyploidy in Asplenium and slight morphologic differences between American and European material, I prefer not to assume its identity to the European plants. In Europe A. ruta-muraria is an abundant plant of masonry, such as the defensive walls of towns and cities; it is very rarely seen on walls in North America, presumably because they are not old enough.

Synonymy ⓘ: = Il, Va, WV; = Asplenium cryptolepis Fernald; > Asplenium cryptolepis Fernald var. cryptolepis – F, Sf; > Asplenium cryptolepis Fernald var. ohionis Fernald – F, Sf; < Asplenium ruta-muraria L. – C, FNA2, K4, Mo1, NE, NY, Pa, RAB, S13, Tn, W; > Asplenium ruta-muraria L. var. cryptolepis (Fernald) Wherry – G, K1, K3; > Asplenium ruta-muraria L. var. lanceolum Christ – K1, K3; > Asplenium ruta-muraria L. var. ohionis (Fernald) Wherry – G

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Heliophily ⓘ: 5