I'm not sure what to call this yucca. All the yuccas of this type that I saw on the Independence Creek Preserve had leaves no more than 5 to 6 mm wide.

Based on the keys in Michael Powell's "Trees and Shrubs of the Trans-Pecos", there are only two short yuccas with stringy-edged leaves like this, Y. campestris (leaves up to 7 mm wide) in loose sand dune areas in the northern Trans-Pecos and Y. constricta in the T-P in Crockett County, but the latter species purportedly has leaves at least 8 mm wide. So neither of those species matches by leave size and range. Another related species is Y. angustifolia/glauca which ranges to the north. Yet neither BONAP nor the PLANTS database show any of these three species occurring in Terrell County.

I suspect these are just narrow-leaved forms of Y. constricta, the closest in both form, habitat, and range. Opinions are welcomed.

ADDENDUM (2/26): I'm adding four more images of this same yucca showing the largest/oldest cluster I documented. This particular clump showed several longish stems up to a meter long, but this was exceptional. Most clusters were shorter or stemless.