Isoëtes piedmontana

Isoëtes piedmontana (N. Pfeiff.) C.F. Reed
(Latin: pes, pedis, a foot, and montanus, pertaining to the mountains, = between the mountains and the coastal plain, the naming author saying, “It is apparently of fairly wide distribution in the piedmont”)

Local names: piedmont quillwort

Leaves usually 7–15(–20) cm long, brownish at base, not shiny, rarely with phyllopods; velum covering less than 1⁄3 of sporangium; megaspores white, not cobwebby, the surfaces microscopically tuberculate to echinate; 2n = 22, 33, 44 (Heafner & Bray 2005). Granite outcrops in temporary pools or shallow depressions; Mason (L.L. Sanchez & J.D. Stanford 2364, BRIT, BAYLU; Holmes et al. 2005), Burnet (Correll & Johnston 17332, TEX-LL, annotated Holmes & Singhurst, SEM at TEX-LL), and Llano (Carr 10569, 11625, TEX-LL, annotated Holmes & Singhurst; Holmes et al. 2005) cos. in Llano Uplift area (Central Mineral Region) of c TX; se U.S., VA to AL, disjunct w to TX. [I. virginica var. piedmontana N. Pfeiff.] Sporulating at least in Apr–May. This disjunct species was first recognized for TX by Holmes et al. (2005); see Fig. 32 and page 31 for a discussion of the disjunction. They noted that it is the only Isoëtes species in the TX flora with megaspores having “a tuberculate to echinate ornamentation pattern not obscured by perine projections.” They also pointed out that it was possible that the species was a hybrid between I. lithophila and I. melanopoda but stated that their detailed study did not support that conclusion. Heafner and Bray (2005) suggested that based on their evidence, “I. piedmontana is best recognized as a complex of cryptic species that [has] evolutionarily distinct origins in their respective geographic ranges” and that ongoing studies will be needed to determine the relatedness of the TX populations to those in the e U.S. It is thus quite possible that the TX populations represent a separate species that will eventually be recognized as distinct. Because of its rareness and limited distribution in the state, we consider this species to be of conservation concern in TX.

: Back to List :