Flora of New Zealand Series

Infl. a many-fld cyme, much-branched or condensed into a compact nead, or fls rarely few or solitary. Fls hermaphrodite, rarely unisexual, sessile or pedicellate, bractlets 2 or 0. Tepals lanceolate, acute, the outer us. longer, slightly more rigid, with narrow membr. margin, the inner occ. almost obtuse, with broader membr. margin. Stamens 6, 3, or variable 3–6. Ovary unilocular, or triseptate, or trilocular. Seeds ∞, often tailed at one or both ends, testa us. finely sculptured. Annual or perennial herbs, tufted or rhizomatous, glab. Lvs flat and grasslike, or tubular or laterally compressed with internal septa, or channelled, or terete like the stems, or reduced to bladeless sheaths; sheath often produced above into 2 obtuse auricles. A cosmopolitan genus of c. 300 spp. Of the 16 N.Z. spp., 12 are found also in Australia and two of these have been recorded from elsewhere in the Pacific; one is an austral circumpolar sp. Three N.Z. spp. are endemic.

SYNOPSIS

• A. Sect. GENUINI: 
• • Plant with horizontal rhizome; infl. apparently lateral; flowering stems with no true lvs and only sheathing bracts at base
  • (a)
  • • Stems light, bright or dark green, or red-brown, us. shining, outline smooth in section:
    • 1, pallidus, 2. pauciflorus, 3. gregiflorus, 4. distegus
  • (b)
  • • Stems blue-green or light green, dull, outline ridged in section:
    • 5. australis, 6. usitatus, 7. sarophorus
• B. Sect. THALASSII: 
• • Plant with horizontal rhizome; infl. apparently lateral; flowering stems with 1–2 terete, green lvs as well as sheathing bracts at base:
  • 8. maritimus var. australiensis
• C. Sect. SEPTATI: 
• • Plant tufted, or with an ascending rhizome; infl. terminal: flowering stems with ∞, transversely septate lvs, both basal and cauline; lf-sheaths with 2 obtuse auricles:
  • 9. prismatocarpus, 10. holoschoenus, 11. novae-zelandiae, 12. pusillus, 13. scheuchzerioides
• D. Sect. GRAMINIFOLII: 
• • Plant tufted; infl. terminal: flowering stems with ∞, basal, non-septate lvs; lf-sheaths without auricles:
  • 14. planifolius, 15. caespiticius, 16. antarcticus

Most spp. flower between November and January, and seed is set from January to February.

The Maori name for rushes and rush-like plants is Wiwi.

Buchenau in Abh. naturw. Ver. Bremen 4, 1875, 393, and in later publications, divided the genus into 8 subgenera now us. treated as sections. Only 4 of these sections are represented in the indigenous flora of N.Z.: sect. Genuini, sect. Thalassii, sect. Septati and sect. Graminifolii.

Many spp. of Juncus have been introduced into N.Z. and J. bufonius, J. plebeius, J. tenuis and J. lampocarpus (= J. articulatus), regarded by Cheeseman in Man. N.Z. Fl. 1925, 295–6, 299, as doubtfully indigenous are now considered to be introduced. J. effusus L. and J. articulatus L. are the most widespread of the introduced rushes. J. effusus, which is most commonly confused with the indigenous J. gregiflorus, may be distinguished by its soft stems with pith continuous in longitudinal section, and by the drooping branchlets of the infl. The septate-lvd J. articulatus may be confused with the indigenous J. holoschoenus, but in J. articulatus the fls are c. 3 mm. long and the black capsules are contracted above to a sharp point, while in J. holoschoenus the fls are 3–4 mm. long and the capsules light brown and gradually tapered towards the tip. Two other introduced septate-lvd spp. which are fairly widespread may also be confused with J. holoschoenus. These are J. acuminatus Michx. with 3 stamens and stiff sharp tepals and J. microcephalus H. B. K. which has 6 stamens and rounded tepals. Edgar in N.Z. J. Bot. 2, 1964, 177–204, gave an account of the N.Z. members of sect. Genuini both indigenous and introduced. Two spp., J. procerus Meyer and J. filicaulis Buch., which were treated in that paper as indigenous, are now considered to be introduced, as also is J. amabilis Edgar which is now recognised as an Australian sp.

Several spp., both native and introduced, are prevalent weeds of damp pastures, swampy ground and drains.

The infl. in Juncus is terminal but appears lateral in spp. of sect. Genuini. In these spp. the infl. is subtended by an erect cylindrical bract which seems to be continuous with the stem below. All shoots produced in summer and autumn are fertile. In winter and early spring, however, the shoot apex aborts and the stem below the apex does not elongate. Instead the uppermost cylindrical lf elongates until it is almost as long as a flowering stem, while the aborted shoot apex may still be found in a small cavity at the base of this elongated, terete, stem-like lf. These lvs have been erroneously referred to as "sterile stems" but Irmisch (Bot. Ztg 13, 1855, 57) showed their true nature. They are, in fact, equivalent to the bract above the infl. of flowering stems.

All spp. known in N.Z. have hermaphrodite fls.

Fig. 12. JUNCUS. Examples of four Sections. Graminifolii : non-flowering plant; leaf-sheath without auricles. Septati : non-flowering plant; portions of leaves seen from the side, showing two different kinds of internal septa and one auricle of each sheath. Genuini : plant-base, showing stems with sheathing scale-leaves. Thalassii : plant-base, showing stems and stem-like leaves. © All rights reserved. [Image: 4X23]

Fig. 13. JUNCUS. Section Genuini. Inflorescence-branchlets: J. gregiflorus, flowers clustered; J. usitatus, flowers evenly spaced. Stems with pith exposed: J. pallidus, pith continuous; J. australis, pith almost wanting; J. sarophorus, pith irregularly interrupted; J. distegus, pith regularly interrupted. © All rights reserved. [Image: 4X24]