Flora of North America species comparison

Genera 29, species ca. 1200 (6 genera, 53 species in the flora).

B. Eriksen and C. Persson (2007) provided a good synthesis of the taxonomic history of Polygalaceae, with modern phylogenetic hypotheses presented by Persson (2001), F. Forest et al. (2007), and J. R. Abbott (2009). All but one of the North American species have traditionally been treated within a broadly defined Polygala. At least six major clades within Polygala (in the traditional broad sense) are represented natively in North America (Abbott). These clades correspond to morphological differences and traditional infrageneric groups, in many cases correlated with geographic distribution. A seventh clade, represented by the type group and based on P. vulgaris, is native to Eurasia and is represented by one sparsely naturalized species. Multiple lines of robust evidence support that four of these native clades are so distant phylogenetically from the type group of Polygala that they can no longer be maintained within Polygala: the groups here recognized as the genera Asemeia, Hebecarpa, Polygaloides, and Rhinotropis, all of which correspond to traditional subgenera.

Much cytological and karyological variation has been documented in the small percentage of Polygalaceae that have been studied cytologically. Some species, including a few North American taxa, have different chromosome numbers, with discrepancies and uncertainties as to the base number for many groups. Even if some reports are in error, evidence of polyploid and aneuploid series is clear, as well as widespread hybridization in a few species, although few reports of hybridization are documented (T. L. Wendt 1978; A. J. Lack 1995). The taxa represented here generally do not intergrade.

The diversity of reported chromosome numbers for North American taxa shows several ploidy shifts, even within some taxa. The exact patterns cannot be fully tracked, given the number of taxa with undocumented chromosome numbers and the absence of solid hypotheses of sister taxa relationships. Despite the shortcomings of current cytological data, further investigations should be useful for illuminating relationships among North American Polygalaceae. There may still be diagnostic value, and even phylogenetic information, in the cytological and karyological data (T. L. Wendt 1978; J. A. R. Paiva 1998).

B. Eriksen and C. Persson (2007) noted Polygalaceae have little economic importance except in herbal medicine (for example, A. Freire-Fierro 1995). The North American Polygala senega is perhaps the most economically important taxon, with some commercial usage globally for various medicinal purposes (J. M. Gillett 1968b; C. J. Briggs 1988). Many species of Polygalaceae are showy in flower and are sometimes cultivated as ornamentals. Most commonly encountered in North America are P. myrtifolia, P. virgata Thunberg, P. ×\dalmasiana L. H. Bailey (perhaps a form of P. myrtifolia), and Polygaloides chamaebuxus (Linnaeus) O. Schwarz.

Use of the term subshrub refers to a low, multi-stemmed, suffrutescent perennial herb; the herbaceous branches may be erect or decumbent, but they are woody above ground proximally. The term subsessile refers leaves with a petiole to 0.5 mm. Measurements of raceme length refer to the flowering and/or fruiting portion (including attachment scars), while width refers to the broadest portion with open (or nearly so) flowers. Raceme shape refers to the flowering and fruiting portion only; with age, there is often an elongated basal portion with scars left by the deciduous fruits. In descriptions of flower color, the outer sepals are not included, and it should be understood that the wings and petals are almost always paler in the proximal portion. The outer sepals are usually green, unless otherwise stated, although it is relatively common for some sepals to be whitish, pinkish, or purplish red marginally. It is also very common for the tips of the upper petals to be darker and for the apex of the keel to be greenish or yellowish. On drying, colors can become darker or paler, with whites often taking on a bluish or pinkish purple tinge, but, unless otherwise stated, the colors do not change dramatically. In key leads and descriptions for Polygalaceae, lower sepals refers to abaxial sepals and upper sepals refers to adaxial sepals; the two lateral (inner, often petaloid) sepals are referred to as wings. In reference to petals, the abaxial (lower) petal is referred to as the keel. Unless otherwise stated, if the sepals are deciduous, so are the wings and corolla; conversely, if the sepals are persistent (unless only the upper one is specified), then so are the wings and corolla. Descriptions of pubescence do not refer to marginal cilia; even a glabrous structure may be marginally ciliate. Measurements of seed length include aril and pubescence; the body itself is usually 0.3–0.7 mm shorter.

(Discussion copyrighted by Flora of North America; reprinted with permission.)