2c. var. mobilense (Regel) Ownbey

A. mutabile Michx.

Aerial stems 10–30(–50) cm long. Leaves 1.0–2.5 mm wide. Bulblets absent. Flower stalks usually very slender, 2–4 times as long as the perianth at flowering. Fruits usually produced. 2n=14. April–June.

Uncommon in the Unglaciated Plains and Ozark Divisions in southwestern Missouri; also disjunct and probably introduced in St. Louis County (Kansas to Texas east to Georgia and Florida, mostly along the Coastal Plain). Prairies and openings of dry to mesic upland forests, in sandy or cherty soils; also along railroads.

This is the least common and least understood phase of the A. canadense complex in Missouri. When seen on some of the prairies of southwestern Missouri, it appears strikingly different, as short plants with dense umbels of relatively short-stalked flowers. However, collections from the Ozarks are less distinct from var. lavendulare morphologically. Steyermark (1963) considered this taxon a potential hybrid between his A. mutabile (treated here as var. lavendulare) and A. canadense (var. canadense), but this is unlikely on morphological grounds and because plants of var. mobilense are the only Missouri diploids in an otherwise polyploid complex (Ownbey and Aase, 1955). A more plausible hypothesis is that var. lavendulare was formed following hybridization and polyploidy between var. mobilense and one of the other diploid, floriferous taxa, perhaps var. fraseri Ownbey, which is widespread in the Great Plains (Ownbey and Aase, 1955).