A new subgenus in Luzula (Juncaceae)

The name Luzula purpurea is well known to those familiar with the literature of cytogeneties. Since the discovery that this species has relatively large chromosomes with diffuse centromeres, it has been the subject of much cytological study. Unfortunately, however, the name L. purpurea has no valid standing under the International Code of Botanical Nomenclature. The specific epithet was originally published, without a description, as JunUow purpureus by Buch (1816). Link, in a publication by Buch (1825) transferred this epithet to Luzula, but again without description. In both of the above citations, the name was attributed to Masson, but patient search has failed to turn up any publication by this worker in which Luzula (or Juncus) p?trpurea was described. The first time the name L. purpurea was published with a description was by Meyer (1849), who attributed the name to Buch and listed "Juncts purpureus Masson mser." as a synonym. The publication of the binomial L. piurptrea by Meyer is, however, antedated by L. elegans Lowe (1838), which is unquestionably the same species. Two other names have been applied to this species. The first, L. berthelotii Nees ex Kunth (1841), is clearly a synonym of L. elegans and the second, L. gracilis, is an herbarium name published by Trimen (1872) in a discussion of the distribution of L. purpurea (L. elegans). The nomenclature of this species has been complicated not only by the nomina nuda that have been applied to it, but also by confusion with another species. As pointed out above, the name Luzula purpurea has been in general use for this species up to the present time. It was taken up by Buchenau (1906) in his comprehensive monograph of the Juneaceae. In this same monograph L. elegans Lowe was listed as a synonym of L. purpurea, and a previously unvalidated herbarium name, "Luzula elegans Guthnick in Sched. hb. azor. Hochsffitetteri (1838) n. 126" was taken up for species currently known as L. purpureosplendens Seubert (1844). It is clear that the name L. elegans Guthnick cannot replace L. elegans' Lowe, as Buchenau evidently intended; Guthnick's name was not published until 1843 (Seubert & Hochstetter 1843), and then as a nomen nudumni. The species Luzula elegans Lowe, up to the present time, has beeni considered a member of the subgenus AntlJielaea. Although it resembles this subgenus superficially, it differs in three major morphological characters that were noticed by Buchenau (1906). First, the main infloreseence axis is actually a pseudorachis, formed by an overtopping of the main rachis by one of the major branches of the inflorescence. At each successive level this "rachis" is again overtopped by another major branch. This can easily be verified by observing the position of the brachts that subtend the major branches and the pedicels of the infloreseence (Fig. 1). In L. elegans each bract surrounds the base of an internode of the upright "rachis" (pseudorachis), indicating that this main axis is actually formed from a series of major infloreseence branches that successively overtop and crowd aside the morphologically terminal rachis. In all other species of