PlantaeDB Logo
Login Sign-up

Genus Blackstonia in Family Gentianaceae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

Do you wish to read more about plant taxonomy? Click here!

Genus Description

Suggest a correction!

Blackstonia (Huds.) is a small annual genus in Gentianaceae, comprising about two species: B. perfoliata and B. officinalis in some treatments, or B. perfoliata and B. grandiflora in others (Flora Europaea, 1972; Rothmaler, 2002; POWO, 2024). Its species range across western and southern Europe, extending eastward to parts of the eastern Mediterranean and north to the British Isles, occupying calcareous grasslands, scrub margins, open woodlands and sea-cliffs, from low elevations to montane zones (Flora Europaea, 1972; Euro+Med, 2006). The generic type is Gentiana perfoliata L., upon which the name Blackstonia was based (POWO, 2024). Individuals are glabrous, erect annual herbs with opposite leaves, often perfoliate or partially connate at the base, small deciduous stipules or interpetiolar membranes, and non-scarious, not keeled sepals (Flora Europaea, 1972). Flowers are in lax cymes; the corolla is rotate to broadly funnel-shaped, deeply lobed, yellow with a contrasting throat, and apically scaled or otherwise specialized at the sinus sinuses; stamens are inserted in the corolla throat with short filaments and anthers that mature later than the stigmas; the ovary is superior with parietal placentation and many ovules; fruit is an oblong, septicidal capsule releasing tiny, wind-dispersed seeds (Flora Europaea, 1972; Nilsson, 2002). The Mediterranean Basin is the main diversity center, with B. perfoliata broadly European and B. grandiflora largely Mediterranean, and B. perfoliata var. lutea recognized by some authors (Flora Europaea, 1972; WFO, 2024). Pollination is generalist insect-mediated by flies and small bees that visit nectar at the corolla base (Möller et al., 2022). The base chromosome number is x = 10; diploids and tetraploids are reported, for example 2n = 38 in B. grandiflora (Charbonnel, 1990; D', 2007).

Within Gentianaceae, Blackstonia belongs to subtribe Chironiinae (Mansion et al., 2005; Fabecki et al., 2023), and recent phylogenetic analyses support its close relationship to Cicendia, from which it is morphologically distinguished by its larger, rotate corollas and perfoliate leaves. Taxonomically, the circumscription of the genus is stable, but the treatment of Mediterranean material differs: B. grandiflora (Asso)B.Schaarschm. is accepted by some and considered conspecific with B. perfoliata by others (Mansion & Struwe, 2004; Rothmaler, 2002). In horticulture, B. perfoliata occasionally appears in wildflower mixes and botanical collections for its ornamental value, while the species is not a major timber, crop or weed and shows no invasive tendencies (Euro+Med, 2006). Populations are declining in parts of western Europe due to habitat loss from agricultural intensification and succession, and accurate taxonomic treatment combined with distribution monitoring remains essential for conservation (IUCN, 2011; Mellor, 2013). As habitat-specific threats intensify, targeted assessments and protective management for calcareous grasslands will be vital to safeguard Blackstonia’s remaining populations.

Pick a Species to see its components: