Drimia


Drimia is a genus of African, south European and south Asian flowering plants. In the APG IV classification system, it is placed in the family Asparagaceae, subfamily Scilloideae. When broadly circumscribed, the genus includes a number of other genera previously treated separately, including Litanthus, Rhodocodon, Schizobasis and Urginea.
One of the best-known species is the sea squill, Drimia maritima. Drimia intricata is sometimes cultivated as a bulbous or succulent plant.

Description

Drimia species are usually deciduous, more rarely evergreen, growing from bulbs. The bulbs may be underground or occur on or near the surface. Each bulb has one to several leaves that are often dry by the time the flowers open. The inflorescence is in the form of a raceme, with one to many flowers. At least the lower inflorescence bracts have spurs. The individual flowers generally last for only one to two days and have white to yellowish green or brown tepals that are either free or joined into a basal tube. The tepals often have a darker central keel. After fertilization, an ovoid capsule forms with several seeds in each locule. The seeds are black and winged.

Taxonomy

A formal description of genus Drimia first appeared in the fourth edition of Species Plantarum, published in 1799, authored by Carl Ludwig Willdenow. The name was attributed to Nikolaus Joseph von Jacquin. When describing Drimia elata in a work published in 1797, Jacquin said that he was unable to assign it to one of the known genera, and so constructed a new one. The name is derived from the Greek δριμεῖα drimeia, the feminine form of the adjective δριμύς drimys meaning "bitter" or "acrid", referring to the root.
The boundaries between genera within the Scilloideae are not completely settled. The situation has been described as being in a "state of flux". As early as 1977, it was suggested that Urginea be merged into Drimia, although other small genera continued to be kept separate. In 2000, Peter Goldblatt and John Charles Manning proposed including other related genera, including Litanthus, Rhadamanthus and Schizobasis, a position supported later by some molecular phylogenetic studies. This broad circumscription of Drimia is accepted by the World Checklist of [Selected Plant Families]. Other sources prefer to maintain a larger number of segregated genera. Regardless of whether a broad or strict view is taken of Drimia, it is placed in the tribe Urgineeae of the subfamily Scilloideae.

''Litanthus'' group

The genus Litanthus was for a long time monotypic, with the sole species L. pusillus, before in 2000 Goldblatt and Manning included it in Drimia. A further species, Drimia stenocarpa, was added to the group in 2014. The Litanthus group is characterized by one- or occasionally two-flowered inflorescences with drooping tubular flowers whose tepals are united at the base for more than half their length.

''Rhodocodon'' group

The genus Rhodocodon was included in Drimia by Goldblatt and Manning in 2000. The species of Rhodocodon, or the Rhodocodon group within Drimia, including D. cryptopoda, form a well supported clade endemic to Madagascar. They appear to be the product of a single invasion of Madagascar by an African species. A total of 13 species are recognized by those who separate the genus from Drimia.

''Schizobasis'' group

The genus Schizobasis was included in Drimia by Goldblatt and Manning in 2000. As many as eight species have been described, but in 2014 these were reduced to two: Drimia intricata, including all the previously described species, and the new species Drimia sigmoidea. The Schizobasis group is distinguished by its well branched, thin-stemmed inflorescence and small, filiform leaves that are found only in seedlings, disappearing in mature plants.

Species

, Plants of [the World Online] accepts 130 species.
In addition, 10 species described in 2015, and placed by the authors in Rhodocodon, are, as of 2017, treated as "unplaced" in the World Checklist of Selected Plant Families, which does not recognize the genus; none have names in Drimia:
  • Rhodocodon apiculatus H.Perrier ex Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon calcicola Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon campanulatus Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon cyathiformis H.Perrier ex Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon floribundus H.Perrier ex Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon graciliscapus Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon intermedius H.Perrier ex Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon linearifolius Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon monophyllus Knirsch, Mart.-Azorín & Wetschnig
  • Rhodocodon rotundus H.Perrier ex Knirsch, Mart.-Azorín & Wetschnig

    Distribution and habitat

The broadly defined genus has about 130 species found in Africa, including Madagascar, the Mediterranean region and southern Asia. About half of all the species occur in southern Africa, where species diversity is greatest in semi-arid regions with winter rainfall. Drimia generally is found in regions with seasonal dryness.