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Volume II (1970) - Flora of New Zealand Indigenous Tracheophyta - Monocotyledons except Graminae
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Scirpus L.

SCIRPUS L., 1753

Type sp.: S. sylvaticus L. from Europe and N. America.

Infl. terminal or apparently lateral, corymbose, capitate, paniculate, spicate, or reduced to a single spikelet; subtending bracts several, lf-like, or 1 only, glume-like or culm-like, continuous with the culm. Spikelets 1-∞, us. many-fld. Glumes spirally imbricate round the rhachilla, all floriferous or the lowest 1, or rarely 2, empty; fls hermaphrodite. Hypog. bristles 2–8–(12), or 0. Stamens 3 or fewer. Styles 2- or 3-fid, not swollen at base. Nut us. obovoid, ellipsoid, trigonous, plano-convex or biconvex, us. apiculate. Glab., annual or perennial herbs, small and tufted, or slender and floating, or with a creeping rhizome and then often tall and stout. Culms terete or 3-angled. Lvs few to ∞ at base of culm, double-folded, terete or trigonous, or very slender and grasslike, or reduced to sheathing bracts. Cosmopolitan with c. 300 spp. Of the 23 N.Z. spp. only 6 are endemic; almost all the remaining spp. are recorded from Australia and many of these are cosmopolitan or widespread in the N. or S. Hemispheres.

SYNOPSIS

  • A. Sect. SCIRPUS. 
    • Robust, summer-green perennial. Rhizomes forming globose ligneous tubers. Lvs ∞, with well-developed laminae. Infl. a terminal, irregular umbel or cluster of spikelets subtended by several lf-like bracts. Hypog. bristles present. Nut > 3 mm. long:
    • 1. fluviatilis, 2. medianus, 3. caldwellii
  • B. Sect. ACTAEOGETON, series Lacustres (sect. SCHOENOPLECTUS auct.) 
    • Robust perennial. Lvs reduced to sheaths, or a few like the culms. Infl. an apparently lateral, irregular umbel or cluster of spikelets subtended by a single bract appearing as a continuation of the culm. Hypog. bristles present. Nut > 2 mm. long:
    • 4. lacustris, 5. americanus
  • C. Sect. HOLOSCHOENUS. 
    • Robust perennial. Rhizome short. Infl. an apparently lateral, hemispherical head of densely crowded spikelets, subtended by a semiterete bract appearing as a continuation of the culm. Hypog. bristles 0. Nut c. 1 mm. long:
    • 6. nodosus
  • D. Sect. ISOLEPIS. 
  • E. Sect. ELEOGITON. 
    • Perennial aquatic or semi-aquatic plants with elongate, slender, branched lfy culms. Spikelets solitary; subtending bract 0 or inconspicuous. Hypog. bristles 0. Nut c. 1.5 mm. long:
    • 22. crassiusculus, 23. fluitans

Key

1
Lvs several per culm, plant conspicuously lfy
2
Lvs 1–(3) per culm, or 0, plant not noticeably lfy
14
2
Lvs > 2 mm. wide
3
Lvs < 1 mm. wide
5
3
Nut trigonous, equilateral, dorsal angle acute; style-branches invariably 3
1. fluviatilis
Nut lenticular, plano-convex, or trigonous with dorsal angle obtuse; style-branches 2 only, or 2 and 3
4
4
Style-branches 2; nut lenticular with concave sides
3. caldwellii
Style-branches 2 and 3; nut plano-convex to trigonous with convex sides
2. medianus
5
Style-branches invariably 3
6
Style-branches 2, or variable 2–3
10
6
Stamens 3 per glume, very rarely 1–2 in upper part of spikelet; nut trigonous or plano-convex, angles not ribbed
7
Stamens 1–2 per glume, rarely 3 in lower part of spikelet; nut trigonous, angles slightly ribbed
8
7
Glume-margins and nut tapered towards the tip; nut us. cream; plants us. < 6 cm. tall; lvs us. > culms
16. aucklandicus
Glume-margins and nut rounded towards the tip; nut red-brown or dark grey; plants us. > 6 cm. tall; lvs us. < culms
15. cernuus
8
Culms us. > 0.5 mm. diam.; spikelets us. dark purple-red at base, light green above
11. praetextatus
Culms us. < 0.5 mm. diam.; spikelets uniformly light green or reddish black
9
9
Culms us. < 6 cm. long; nut < 1 mm. long; stamen 1, rarely 2–3 in lowermost glumes of spikelet
14. subtilissimus
Culms us. > 6 cm. long; nut > 1 mm. long; stamens varying within spikelet from 3, to us. 2, to 1 above, very rarely 1 in all glumes
13. habrus
10
Infl. subtended by lf-like bract (bract occ. deciduous when nuts are ripe); nuts c. 1 mm. long or less
11
Infl. without subtending bract (aquatic plants occ. with setaceous bract); nuts c. 1.5 mm. long
13
11
Infl. of 3–6, rarely 1–2 spikelets; bract subtending infl. < 1/6 length of culm; lvs us. < culms
12. pottsii
Infl. of 1–(2) spikelets; bract subtending infl. from ¼–2 × length of culm; lvs us. > culms
12
12
Nut almost black, dorsally rounded; culms us. < 2 cm. tall; spikelets <2 mm. wide
18. basilaris
Nut pearl-grey, compressed; culms us. > 2 cm. tall; spikelets us. > 3 mm. wide
17. caligenis
13
Stamens 3; spikelets (2)–3–5 mm. wide
22. crassiusculus
Stamens 2; spikelets 1–2 mm. wide
23. fluitans
14
Glumes with entire margins, lateral veins conspicuous
15
Glumes with fimbriate margins, lateral veins 0
23
15
Stamens 3 per glume, very rarely 1–2 in upper part of spikelet
16
Stamens 1–2 per glume, rarely 3 in lower part of spikelet
20
16
Spikelets ∞
17
Spikelets 1–(4)
18
17
Rhizomatous; culms rigid; infl. not proliferous
6. nodosus
Tufted; culms soft; infl. often proliferous
7. prolifer
18
Glumes only slightly concave, keel not prominent; perennial, ± rhizomatous
15. cernuus
Glumes strongly keeled; annual, tufted
19
19
Glumes yellowish with a large red patch on each side of keel
21. antarcticus
Glumes white or grey, tinged with light brown
20. platycarpus
20
Spikelets > 1.5 mm. wide; glumes obtuse, margins flattened at tip beside keel; culms erect, us. c. 1–1.5 mm. diam.
21
Spikelets < 1.5 mm. wide; glumes acute, margins pinched in at tip beside keel; culms often drooping, < 0.5 mm. diam.
22
21
Style-branches 3; nut trigonous
9. inundatus
Style-branches 2; nut plano-convex
8. sulcatus var. distigmatosus
22
Glumes 1–2 mm. long; nut white or cream; spikelets often proliferous
10. reticularis
Glumes 0.5–1 mm. long; nut grey to black; spikelets not proliferous
19. chlorostachyus
23
Culms terete; spikelets ∞
4. lacustris
Culms trigonous; spikelets 1–4
5. americanus

The introduced sp. S. setaceus L. may be distinguished from all indigenous spp. by its longitudinally ribbed nut.

The genus has been variously divided into sections, many of which have been published as separate genera and are accepted as such by many authors. Koyama (J. Fac. Sci. Tokyo Univ. (Bot.) 7, 1958, 271) has divided the genus into 17 sections, one of which, Desmoschoenus, is here treated as a separate genus. In the following synopsis Koyama's sections are used but the characters given for each are those of N.Z. representatives only.

Van der Veken (Bull. Jard. bot. État Brux. 35, 1965, 285–354) distinguished several types of embryo within Scirpus sens. lat. and considers that the genus can be subdivided into 6 groups on the basis of embryo type. The N.Z. spp. would fall into 3 of his groups (op. cit. p. 346), i.e. Sect. Scirpus in group 3, sect. Actaeogeton (Schoenoplectus) in group 6 and sects Holoschoenus, Isolepis and Eleogiton in group 5. Van der Veken also included Desmoschoenus in group 5 but noted that Desmoschoenus had such a special type of embryo and habit that it would be better classed as a separate genus (op. cit. p. 347).

Flowering us. occurs from October to February and fr. is ripe c. 2 months after flowering.

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