[irn: 13786]

  • Authority

    Balslev, Henrik. 1996. Juncaceae. Fl. Neotrop. Monogr. 68: 1-167. (Published by NYBG Press)

  • Family

    Juncaceae

  • Scientific Name

    Rostkovia

  • Type

    Type species. Rostkovia magellanica (Lamarck) J. D. Hooker.

  • Description

    Genus Description - Erect, glabrous, perennial herbs. Culms without leaves. Leaves all basal, spirally arranged, linear or with reduced blade, stomata restricted to 2 narrow bands of lighter color, one on each side of the midrib. Flower terminal, single on the culm, large, perfect. Stamens 6, with linear, mucronate anthers. Ovary sessile. Style with 3 tapering, twining stigmas. Capsule suborbicular, unilocular or slightly 3-septate, sessile. Seeds many. The name Rostkovia honours F. W. G. Rostkov (1770-1848), a student of Willdenow and a medical counsellor in Stettin, in present-day Poland, and author of a monograph of Juncus in 1801.

  • Discussion

    Taxonomic History of Rostkovia

    Rostkovia was erected as a genus by Desvaux (1809) to accommodate one species, Juncus magellanicus, which Lamarck (1789) had described. Desvaux gave it the new name Rostkovia sphaerocarpa. The most important diagnostic features mentioned were the globose, unilocular, and non-dehiscing capsule. Rostkovia was not immediately accepted, and several authors retained the name Juncus magellanicus (e.g., E. Meyer, 1822; Laharpe, 1825; Gaudichaud, 1825; Dumont d’Urville, 1826; Schultes & Schultes, 1829; Kunth, 1841). J. D. Hooker (1844) used the name Rostkovia again and made the combination with the original Lamarckian specific epithet. He also included in Rostkovia the species that are now referred to Marsippospermum, because they also have ‘singularly large and solitary flowers . . . together with the elongated style and the disproportionate size of the stigmata [which are] characters peculiar to all of these, and appear of sufficient importance to warrant the retaining them under a separate generic name.’ Buchenau (1879, 1890, 1906) treated Rostkovia as a monotypic genus, as it was originally described. He distinguished it from Marsippospermum on the basis of its long leaf-like (vs. small and scariose) inflorescence bracts, 1 cm (vs. 1.5-4 cm) long flower, obovate (vs. scobiform) seeds, and canaliculate (vs. terete) leaf blade. To the characters peculiar to Rostkovia can now be added that the stomata are restricted to two narrow bands, one on each side of the midrib, which is unique in the family. Christophersen (1944) described a second species, R. tristaniensis, from the island of Tristan da Cunha in the Atlantic Ocean (Type. Mejland 1516. holotype, 0!, photo NY!; isotypes, BM!, GH!, K!, O!). Only one species occurs in the neotropical area.

  • Distribution

    Rostkovia includes two species; one (R. tristaniensis) is endemic to Tristan da Cunha, and the other (R. magellanica) occurs on the sub-Antarctic islands from New Zealand to South Georgia and on the mainland of South America, disjunctly between Patagonia and Ecuador.

    Ecuador South America| Peru South America| Bolivia South America| Paraguay South America| Argentina South America| Chile South America| New Zealand