Senega officinalis

Pastore et al. (2023) transfer Polygala senega to Senega officinalis but do not publish combinations for infrataxa in the species. FNA (vol. 10, 2021) also did not distinguish infrataxa. In contrast, Weakley (2025) recognizes two unnamed varieties var. 1 [=officinalis] and var. 2 [=latifolia] which correspond to the two varieties recognized by Kartesz (1994) in Polygala senega (typical variety and variety latifolia).

Polygala senega is very widespread in the eastern United States and southern Canada, although unevenly distributed, and it has fairly often been reported as locally frequent or common. The species occurs in a range of habitats, some of which (e.g. mesic or dry woodlands) are widespread and plentiful. However, the ecological requirements of the species do not seem to be well understood. Also, there may be two biological entities (e.g. varieties or species) within Polygala senega as presently understood; if so, the conservation status of each taxon should be assessed independently.

The roots of Polygala senega have long been used medicinally as the product "Senega Snakeroot" (or similar names). The extent and intensity of collecting for the medicinal trade may be affecting significant populations or portions of its range, so that perhaps Polygala senega is being seriously changed genetically and in decline as a truly wild-functioning species. As well, there are a considerable number of states and provinces that have recognized vulnerability or even loss of populations within their areas of geographical expertise.

Canada from Quebec and New Brunswick to British Columbia; southward in the U.S. east of the Rocky Mountains (except Montana) to Wyoming and Oklahoma, eastward (except Alabama) to Georgia, and northward through New England (except New Hampshire) to Maine (Kartesz 1999, Fernald 1970).

Hinds (1986) reported that the species is uncommon and scattered in New Brunswick, but can be locally common in the western counties of the province. Manitoba Agriculture and Food (2000) state that it is found quite commonly throughout the southern part of their province. Voss (1985) said it is surprisingly spotty in its distribution in Michigan, although locally frequent. In a northern Illinois county, Fell (1955) reported that the species was common in two quite different situations: wooded streambanks, and low prairies. Cusick and Silberhorn (1977) considered it to be rare in unglaciated Ohio.

Medley (1993) reports that Polygala senega var. latifolia is frequent in mesic woodlands in several of the floristic regions in eastern and central Kentucky, whereas P. senega var. senega is rare in prairie patches in two of the central regions. Strausbaugh and Core (1978) stated that in West Virginia P. s. var. senega is mostly in 14 mountain counties, whereas P. s. var. latifolia had been found in just one county.

There is evidence, acquired from reliable sources, of wild-collection of this plant for trade.

Over 90% of wild senega roots exported from Canada originates in Manitoba (Elsasser 1999; Parkland Botanicals 1998). The Saskatchewan Herb and Spice Association (2000) states that most [wild] senega presently harvested comes from Manitoba and eastern Saskatchewan (although it is not clear whether this statement is intended to apply to Canada alone or includes the United States). Manitoba Agriculture and Food (2000) state that wild populations in Manitoba and Saskatchewan are currently the major sources of supply for the North American market, and that a large tonnage is also being exported to Europe. Demand is estimated to have an annual growth rate of 5%. Because of overharvesting in past years, they state that there is a great need to cultivate the species.

Felter and Lloyd (1898-1900) mentioned that in commerce a distinction was sometimes made between Southern and Northern Senega. The former came from North Carolina, Virginia, Tennessee, Kentucky, Ohio, Indiana, Illinois, Missouri and Arkansas; the latter, with a larger root crown and root [and which they thought might be a botanical variety], was bought (since about 1871) from Minnesota and Wisconsin.

Historically over 90% of the wild senega roots exported from Canada has originated in Manitoba, which is said to also be the current situation. Elsasser (1999) of Parkland Botanicals (in Togo, Saskatchewan) reports that the export records of Canada's Dominion Bureau of Statistics for 1919 to 1957 show that root collection (as fresh weight) varied from a high of 1,820,000 pounds in 1930 to lows of 455,000 pounds in 1955 and 1923. Parkland Botanicals (1998) gives the peak year as 1931 (citing the same source), with an export of 2,000,000 pounds fresh (equals 781,000 pounds of dry roots). These records do not include domestic sales. The trade was much diminished in the 1960s-1980s because of a shift to synthetic chemical compounds.

Recent resurgence of interest in use of natural chemical compounds obtained from raw plant materials has sparked a renewal in the industrial herb trade (Elsasser 1999, Parkland Botanicals 1998). Elsasser (1999) considers the present harvests to be about 10-20% of historic levels, stating that the current annual collection of wild roots in Canada is 100,000 pounds fresh (40,000 pounds dry), with over 90% as usual from Manitoba.

The roots are utilized medicinally, after they have been removed from the knotty crown of the rootstock (Veninga and Zaricor 1976). Root extracts are considered effective for several medicinal uses (e.g. Tierra 1988) since they contain methyl salicylate (Foster and Duke 1990), glycosides, and several other drug compounds (e.g. polygalic acid, senegins, saponins) (Saskatchewan Herb and Spice Association 2000, Kako et al. 1996, Hill 1952). The Saskatchewan Herb and Spice Association (2000) states that senega is an official drug in Germany and France, and is valued for its stimulating and expectorant properties, and that the root also has an essential oil (yield 4.5%). Manitoba Agriculture and Food (2000) state that senega snakeroot is officially recognized as a medicinal herb in Canada (Health Canada-registered 'Herb and Natural Product') (cf. Briggs 1988), Germany (Commission E) and the United Kingdom (General Sales List).

The Saskatchewan Herb and Spice Association (2000) indicates that the flowers are also used [although it appears that this is only to a minor extent].

Michael McGuffin (pers. comm.) said that the American Herbal Products Association fairly recently surveyed its members regarding their trade in various species. He stated that their figures should be considered preliminary, and in general might include some double counting (if one company supplied another), resulting in over-reporting by as much as twice the actual amount. Those members who responded reported that about 600, 2000 and 6000 pounds of dried [presumably wild] roots were supplied respectively in 1990, 1991 and 1992; these might be the maximum totals and the actual totals perhaps only half the above (McGuffin pers. comm.). Although these figures might indicate their trade is going up, he considers senega snakeroot in a long-standing traditional and minor trade, but is not personally familiar with seeing it in the market.

Elsasser (1999) of Parkland Botanicals (in Togo, Saskatchewan) states the current annual harvest of wild roots in Canada to be 40,000 pounds dry weight (100,000 pounds fresh weight). He considers this about 10-20% of historic levels. He stated that most of the 1919-1957 exported production was shipped to England and the U.S., with smaller amounts sold to importers in France, Germany and Italy. Manitoba Agriculture and Food (2000) state that in 1995, most of the 10 tons of wild-harvested root product went to Japan, Europe, and the U.S.

Donais (1997) says that other species like senega root have been very hard hit by habitat loss and overgrazing in agricultural areas [his focus is Canada]. In Maine (and some other states) the species is known to have lost range and habitats to general land conversion (agriculture, urbanization).

Donais (1997) says that the species is not endangered over its entire [Canadian] range; "in parts of northern Alberta, Saskatchewan and especially Manitoba, where rocky native habitat has not been invaded by cattle or destroyed by cultivation, vast stands of senega roots can still be found". Elsasser (1999) also states that Polygala senega is distributed extensively in Manitoba [cf. Scoggan 1957], and that much of the province is rough limestone land that remains uncultivated, ungrazed, and unsuitable for forestry.