Vascular Plants of North Carolina

Account for Weakleaf Yucca - Yucca flaccida Haworth

Section 5 » Order Liliales » Family Agavaceae

Author	Haworth
Distribution	Primarily in the southwestern Piedmont, and to a lesser extent the southern Mountains. A few records farther east in the Piedmont and Coastal Plain and from the northern Mountains, but these might be of non-natural populations. As this is a recent split from Y. filamentosa, it is likely that the species is under-collected/reported. Weakley (2018) suggests that records from NC and SC are not native occurrences. Poorly known, especially for the native range. Apparently from NC to northern FL, and west to TN and LA. Weakley (2018) considers records from GA, FL, AL, and MS as native, but is uncertain about whether it is native as far north as SC and NC. Obviously much is to be learned about this taxon.
Abundance	Apparently rare to uncommon in the southwestern Piedmont, rare in the southern tier of Mountain counties, and extremely rare elsewhere in the state. It is considered as an NC Watch List species. With collection records from at least 12 counties, scattered across much of the state, the State Rank is certainly not as rare as the NC NHP's rank of S1?. This website considers a rank of [S2?] to be more in line with the information available.
Habitat	This is a taxon of dry and somewhat open woodlands, as is Y. filamentosa. It occurs around granitic flatrocks and perhaps domes, and in other types of partly sunny sites. More information is needed on whether habitats differ from those of the much more common Y. filamentosa.
Phenology	Probably blooms mostly from late April into July, and fruits in September and October.
Identification	This is a yucca that is quite similar to Y. filamentosa, being a basal rosette of long and quite slender evergreen leaves to 1.5-2 feet long. However, the leaves are mostly around 1 inch wide, narrower than on Common Yucca, and they are considerably more pliable than the relatively stiff leaves of Common Yucca. The other main distinction is that Weakleaf Yucca has rough, strongly pubescent branches in the inflorescence, as opposed to smooth/glabrous branches in the inflorescence in the common species. As mentioned above, this is a poorly known taxon in NC and other Southeastern states, perhaps not really rare at least in the southwestern Piedmont; closer scrutiny and collections of yuccas (at least the leaves) in the Piedmont and mountains is warranted to further document its range and abundance, plus whether it might be native in the state.
Taxonomic Comments	This is a fairly recent, and still controversial, split. Weakley (2018) expresses some question about whether this is a good species. It was formerly considered as a variety – Y. filamentosa var. smalliana – of the widespread Common Yucca. NatureServe does not list a “Q” on the Global Rank and thus considers this as a good species.
Other Common Name(s)	None specifically for this taxon, but the usual Adam’s-needle, Spoonleaf Yucca, etc., for the combined two species.
State Rank	S1? [S2?]
Global Rank	G5
State Status	W7
US Status
USACE-agcp
USACE-emp

County Map - click on a county to view source of record.