Digitalis minor is a species of flowering plant in family Plantaginaceae, which has been called dwarf Spanish foxglove. It is a biennial or short-lived perennial species of foxglove which is endemic to the Balearic islands with large, pendulous, pink or purple flowers. Closely related to the common purple foxglove, it is best distinguished by its small fruits. It is one of the only foxgloves to grow in calciferous, alkaline soils.
Local vernacular names in the Catalan language are: didalera, didals, didals de la Mare de Déu, boca de llop and herba de Santa Maria.
Taxonomy
For a long time this species was known under the name of Digitalis dubia, now considered a synonym of D. minor, but until recently this name was still considered to be the correct name of this species outside of Spain (i.e. in the Flora Europaea (1976), and the Euro+Med Plantbase (2011)).
The present name is indeed older and has priority, that is, should both names describe the same taxon; Linnaeus first described a taxon under the name D. minor in 1771, only writing "habitat in Hispania" regarding its origin. Only recently have foreign institutions such as the Plants of the World Online (2017) accepted the priority of Linnaeus, although Spanish botanists had been using the name as early as the 1990s.
Linnaeus was actually not the first to describe this species; in his 1771 work he cites Joseph Pitton de Tournefort's 1700 Institutiones rei herbariae, first published in 1694 as Eléments de botanique, ou Méthode pour reconnaître les Plantes, as the source of the taxon. Tournefort calls the taxon Digitalis Hispanica, purpurea, minor. Tournefort was not the first to describe the plant either, in his book he cites two older botanical works for this taxon, Paolo Boccone's 1697 Mvseo di fisica e di esperienze variato and Jacques Barrelier's Plantae per Galliam, Hispaniam et aliam observatae, at the time an unpublished manuscript composed in 1697, but eventually published in Leiden in 1714. Both Barrelier and Boccone described the plant as having the leaves of a Verbena and having collected it in Spain.
D. dubia was first described by the Spanish botanist Juan Joaquín Rodríguez y Femenías in 1874, who states that the name D. minor, as applied to the flora of Menorca by Pierre André Pourret (it had also been identified as D. thapsi in other 19th century works), was not the same species as D. minor as it was originally used by Linnaeus, which he did not believe occurred on Menorca. According to the table provided by Rodríguez, D. dubia was distinguished from D. minor, at least in the herbarium, by having secondary leaf veins which run straight as opposed to bending towards the apex; non-swelling, downturned pedicels twice the length than the calyx as opposed to patent, swelling in size at their apex, and shorter than the calyx; and the calyx segments being oval and rounded with blunt apexes, as opposed to lanceolate and lanceolate-oval with sharp apexes.
In 1881, in his book series attempting to list all the plants of Europe, the Conspectus Florae Europaeae, Carl Fredrik Nyman (assisted by Eugène Bourgeau in this part) followed Rodríguez, listing both his name D. dubia (and following his synonymy) and Linnaeus's D. minor, which according to them had been collected in Cordova.
Varieties
This species is highly polymorphic; it is phenotypically diverse with individuals being quite different from each other. Until recently there were two varieties recognised, although the Flora Iberica no longer does so: Digitalis minor var. minor which is covered with pubescent hairs (trichomes). Digitalis minor var. palaui which is hairless (glabrous). Such plants occur on both Minorca and Majorca.
In 1914 Carlos Pau y Español published Digitalis dubia var. longipendunculata described by Pius Font i Quer in a letter from Menorca to him. This variety supposedly had pedicels twice the length than the calyx and green leaves weakly tomentose on their undersides. Pau expressed doubt as to the validity of the taxon. A pharmacist and botanist from Mallorca, Llorenç Garcías i Font, described another two varieties from his island in 1958, both named after local botanical friends: subsp. dubia var. marcosii and subsp. palaui. According to him, subsp. palaui had much larger, green, glabrous, leaves which were more lanceolate and more attenuated. The pedicels, branches, bracts and sepals were puberulent and purplish. The variety marcosii was supposedly intermediate between the two.
Angel María Romo Díez promoted the taxa to the rank of subspecies in his 1994 book Flores silvestres de Baleares.