A more precise lectotypification of Juncus bulbosus L. (Juncaceae)

Abstract

During studies on the bulbous rush, Juncus bulbosus L., 1753 its lectotype sheet (Herb. Linn. No. 449.27 LINN; Snogerup, 1985) was found to be heterogeneous: two specimens are glued to the same sheet (Fig. 1). A detailed morphological examination of both specimens revealed that one of them (that on the left side of the sheet) was certainly not a Juncus. This sterile plant has clearly different leaves. They are triangularly canaliculate (with a deeper groove in the middle and two shallower grooves on the sides) and linear. Their margins are narrowly upturned. The apical parts of the leaves in cross-section are oval, with sharp, narrow, elongate ridges. Slightly below the apices the cross-section becomes triangular, and then, from about 1/4 way down from the apex, flat, linear (grass-like), ca. 1.3-1.4 mm wide, gradually widening toward the base. The sheath is typical of sedges (Carex)-membranous. There are no auricles. The shoot grows from an elongate, thin, rhizome/stolon (yellowish-orange, with pale orange medulla). Based on this description, the sterile specimen resembles one of the narrow-leaved species of Carex and cannot be regarded as J. bulbosus. Besides, J. bulbosus does not form rhizomes (e.g., Snogerup, 1980), nor subterranean stolons, which are distinctly developed in the specimen described. The other, right-hand, specimen represents Juncus bulbosus as this name is currently applied. It matches the protologue of the name (Linnaeus, 1753: 327), the flowering specimen showing the slight basal bulb-like swelling that provides the epithet (bulbifer). The leaves are terete and imperfectly septate, therefore not articulate (foliis teretibus non articulosis). They are also linear and canaliculate (foliis linearibus canaliculatis). The capsules are obtuse (capsulis obtusis), triangular (c. triangularibus) and ovate (c. ovatis), but the inflorescence lacks proliferating flowers (panicula prolifera), probably because the specimen was growing in a moderately humid place. Since only one plant on the lectotype sheet corresponds to the protologue, according to the Code (Greuter & al., 2000: Art. 9.12 & Art. 9.14) Snogerup's (1985) lectotypification must be made more precise and limited to only one specimen: Juncus bulbosus L., Sp. PI.: 327. 1 May 1753. Lectotype (designated by Snogerup, 1985: 20; confirmed pro parte here): Herb. Linn. No. 449.27, right-hand specimen (LINN). The flowers of the lectotype plant have three stamens and obtuse inner perianth-segments. The capsule is oblo g, obtuse at apex, and with a short mucro. The m ture capsule exceeds the perianth. Therefore, the lectotype plant represents Juncus bulbosus s.str. as generally understood [i.e., it is not J. bulbosus subsp. kochii (F. W. Schultz) Reichg.].