Flora of New Zealand Series

Bulbous Rush

Low-growing perennial, very variable, densely tufted, 5-15- (25) cm high, or with prostrate rooting stems with leafy tufts at nodes, often mat-forming, usually reddish-tinged, or submersed. Stems slender, ± swollen at nodes, rooting. Leaves setaceous, short, (very narrow and grass-like in some floating plants), transverse and longitudinal septa present but scarcely visible externally. Inflorescence very variable, unbranched, and few-flowered, or branched and open, with flowers only, or tufts of setaceous leaves with or without flowers. Flowers 2-6 in each cluster. Tepals c.2 mm long, acute, green to brown. Stamens 3-6. Capsule 2-3 mm long, ± = or > tepals, yellowish-brown, oblong to obovate, obtuse, subacute or ± retuse.

N. North Auckland - Kerikeri Inlet, near Dargaville; South Auckland; Wellington - Tararua Range, upper Hutt Valley, Summit Railway settlement (Rimutaka Range). S. Nelson - locally abundant over large area in Buller; Westland; Canterbury - near summit of Arthur' s Pass, Lake Pearson, near Waimakariri River mouth; Fiordland - Lake Manapouri, Lake Orbell; Southland - Waitutu River mouth, near Colac, Awarua Plain. St. In swampy situations in higher rainfall districts. (Eurasia, N. Africa)

First record: Allan 1940: 308, as J. supinus Moench.

First collection: Taheke, D. Petrie, Jan. 1896 (AK 3051).

J. bulbosus is distinguished by the mat-like growth of setaceous leaves which may also occur in tufts at each flower-cluster and at times entirely replace the flowers, and by the yellowish-brown capsules ± = tepals. In aquatic places leaves may be longer and grass-like, and the plant confused with forms of J. bufonius, but the leaf septa, and slender, ± swollen, rooting stems distinguish J. bulbosus from J. bufonius.

"Bulbous rush" is a widely occurring and abundant element in wet pastures on the west coast of S. Id, and especially widespread in pakihi. It is common in swards it wet valley bottoms of streams entering the upper Hutt Valley, and on wet hillsides, western slopes of the Rimutaka Range, - north from old Summit Railway Station. Essentially a plant of higher rainfall areas, but, as the Waimakariri River mouth occurrence indicates, it could be found in swampy sites in low rainfall districts.

Mason (N.Z. Weed & Pest Control Conf. Proc.17, 1964, 244) recorded that "J. bulbosus var. kochii with 6 stamens also occurs." Specimens with 6 stamens have been collected from near Dargaville and in the Buller County, Nelson Land District. In Europe, plants with 6 stamens have been treated as a distinct sp. J. kochii F.W. Schultz but Stace (Hybridization Fl. Brit. Is 1975, 467) noted "There is a disagreement as to whether or not these two species are distinct and on the characters which should be used to separate them."Benoit and Allen (Proc. Bot. Soc. Brit. Is 7, 1968, 504) discussed characters distinguishing the two taxa in Britain; N.Z. plants with 6 stamens have anthers much < filaments, usually dark brown tepals and ± obovate, retuse capsules, but all these features can be found in various combinations in plants with 3 stamens.

Juncus uliginosus, lesser bog rush, was recorded by Dalgleish (N.Z. J. Agric. 28, 1924, 29) as rapidly covering unlimed heavy pasture soils in Westland. This may refer to J. bulbosus, as J. uliginosus Roth is a synonym of J. bulbosus, but no specimen has been found.