Flora of the Southeastern United States

Senega Spach. Common name: American-milkwort.

Contributed by Alan S. Weakley and Scott G. Ward

Key to Senega

A genus of about 229 species, herbs (less typically subshrubs), of North America, central America, n. and c. South America, the West Indies, and sub-Saharan Africa. Senega is phylogenetically, morphologically, and geographically separated from Polygala, which is Old World (Pastore et al. 2023). All our members of Senega are in subgenus Senega; two other subgenera occur in sw. United States/Mexico and s. South America. Pastore et al. (2023) divided Senega subgenus Senega into 16 sections, of which nine are represented in our region (one section, Trichospermae, only by an introduced, historic waif, S. longicaulis). Many of the sections have long been recognized as natural groups, and some were previously given taxonomic status, sometimes at genus rank (as by Small); they are shown in the key and text.

ID notes: Flowers of Senega consist of an outer calyx whorl of 5 sepals (two of which are petaloid, aka "wings"), and an inner corolla whorl of 3 petals (the two dorsal petals comprising the floral tube). The "keel" refers to the lower petal that bears a fringed crest, acting as a landing platform for pollinators.

References: Abbott (2021) In Flora of North America Editorial Committee (2021); Barger et al. (2023); Eriksen & Persson In Kubitzki, Bayer, & Stevens (2007); Haines (2010); Neubig & Abbott (2020); Pastore (2013); Pastore et al. (2019); Pastore et al. (2023); Smith & Ward (1976); Sorrie & Weakley (2017a); Trauth-Nare & Naczi (1998). Show full citations.

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