Scirpus L.

Volume III (1980) - Flora of New Zealand Adventive Cyperaceous, Petalous & Spathaceous Monocotyledons

SCIRPUS L.

Perennial, occasionally annual, tufted or rhizomatous, stout or slender herbs. Stems terete or 3-angled. Leaves flat or keeled with well-developed laminae, or filiform, reduced to basal sheaths. Inflorescence varying in number of spikelets and degree of branching, from a terminal, much-branched ± umbellate panicle with several leafy bracts, to an apparently lateral single spikelet or small cluster of spikelets, with subterete green bract appearing as a prolongation of the stem. Spikelets usually many-flowered. Glumes spirally imbricate round rhachilla, all floriferous or lower 1- (2) empty; flowers hermaphrodite. Hypogynous bristles c. 6, or often 0. Stamens 3 or fewer. Stigmas 3 or 2. Nut usually obovoid or ellipsoid, trigonous, plano-convex or biconvex. Cosmopolitan genus of c. 300 spp. Native spp. 20, adventive 6.

SYNOPSIS

A
- Robust plants
- 1.
- - Leaves with well-developed laminae. Inflorescence terminal with several leaf-like bracts. Hypogynous bristles present (except in georgianus). (Sect.):
  - 1. *georgianus, 2. *polystachyus, 3. caldwellii, 4. fluviatilis, 5. medianus
- 2.
- - Leaves reduced to basal sheaths or several like stems. Inflorescence apparently lateral, with a bract appearing as a continuation of the stem
  - (a)
  - - Hypogynous bristles present. Nut > 2 mm long. ():
    - 6. lacustris, 8. pungens
  - (b)
  - - Hypogynous bristles 0. Nut ± 1 mm long. ():
    - 7. nodosus
B.
- Slender plants
- 1.
- - Inflorescence of 1-3-several spikelets with a bract appearing as a continuation of the stem. Hypogynous bristles 0. ()
  - (a)
  - - Perennial
    - (i)
    - - Rhizomatous; distinctly leafy, rarely all leaves reduced to basal sheaths:
      - 9. *setaceus, 10. aucklandicus, 11. basilaris, 12. caligenis, 13. cernuus, 16. habrus, 17. pottsii, 18. praetextatus, 19. subtilissimus
    - (ii)
    - - Tufted; few-leaved or leaves all reduced to basal sheaths. Inflorescence often with proliferous off-shoots:
      - 20. inundatus, 21. prolifer, 22. reticularis, 23. sulcatus var. distigmatosus.
  - (b)
  - - Annual, tufted:
    - 24 *antarcticus, 25. *chlorostachyus, 26. *platycarpus
- 2.
- - Inflorescence a solitary spikelet; bract 0 or inconspicuous. Hypogynous bristles 0. ():
  - 14. crassiusculus, 15. fluitans.

Key

Plants robust, tufted with leaves > 2 mm wide or stoutly rhizomatous; or plants aquatic to semi-aquatic with ebracteate inflorescence

Plants slender, tufted with leaves < 1 mm wide or 0, or with slender rhizomes, all terrestrial with bracteate inflorescence

Inflorescence terminal with several wide leaf-like bracts; leaves many, > 2 mm wide, flattened

Inflorescence apparently lateral with a single stem-like bract, or ebracteate; leaves < 1 mm wide, few and ± 3-angled if wider, or reduced to basal sheaths

Plants lacking rhizomes and woody tubers; spikelets < 1 cm long

Plants with rhizomes and woody tubers; spikelets > 1 cm long

Leaves double-folded; hypogynous bristles 0 (in N.Z. plant)

1. *georgianus

Leaves channelled; hypogynous bristles present, much > nut and folded and twisted at maturity

2. *polystachyus

Nut trigonous, equilateral, dorsal angle acute; style-branches invariably 3

4. fluviatilis

Nut lenticular, plano-convex, or trigonous with dorsal angle obtuse; style-branches 2 only, or 2 or 3

Style-branches 2; nut lenticular with concave sides

3. caldwellii

Style-branches 2 and 3; nut plano-convex to trigonous with convex sides

5. medianus

Rhizomes thick, woody, 3-10 mm diam.; inflorescence bracteate; plants terrestrial

Rhizomes slender, 0.5 - 1 mm diam., or plants tufted; inflorescence ebracteate; plants aquatic or semi aquatic

Stems 3-angled; leaves 1-4, channelled, becoming 3-angled like stems

8. pungens

Stems terete; leaves reduced to basal sheaths

Stems > 3 mm diam. with spongy whitish pith; inflorescence an irregular umbel of pedunculate spikelets

6. lacustris

Stems 1-2 mm diam. with dense colourless pith; inflorescence a dense head of sessile spikelets

7. nodosus

Stamens 3; spikelets (2) -3-5 mm wide

14. crassiusculus

Stamens 2; spikelets 1-2 mm wide

15. fluitans

Nut with several well-marked longitudinal ribs and fine transverse bars between ribs

2. *setaceus

Nut not ribbed, or ribbed only on angles, and without transverse bars

Plant rhizomatous

Plant tufted, lacking rhizomes

Style-branches invariably 3

Style-branches 2, or variable 2-3

Stamens 3 per glume, very rarely 1-2 in upper part of spikelet; nut not ribbed on angles

Stamens 1-2 per glume, rarely 3 in lower part of spikelet; nut ribbed on angles

Nut usually red-brown or dark grey; leaves usually < stems

13.cernuus

Nut usually cream; leaves usually > stems

10. aucklandicus

Spikelets usually dark purple-red at base, light green above; stems usually > 0.5 mm diam

18. praetextatus

Spikelets uniformly light green or reddish-black; stems usually < 0.5 mm diam

Nut > 1 mm long; stems usually > 6 cm long

16 habrus

Nut <1 mm long; stems usually < 6 cm long

19. subtilissimus

Inflorescence usually of 3-6 spikelets; leaves usually < stems

17. pottsii

Inflorescence of 1- (2) spikelets; leaves usually > stems

Nut almost black; spikelets < 2 mm wide

11. basilaris

Nut grey; spikelets usually > 3 mm wide

12. caligenis

Stamens 3 per glume, rarely 1-2 in upper part of spikelet

Stamens 1-2 per glume, rarely 3 in lower part of spikelet

Glumes strongly keeled; annual

Glumes not prominently keeled; perennial

Glumes yellowish with a large red patch on each side of keel

24. *antarcticus

Glumes white or grey, tinged with light brown

26. *platycarpus

Inflorescence of many spikelets, often proliferous; stems usually 1-3 mm diam.

21. prolifer

Inflorescence of 1- (2-3) spikelets, not proliferous; stems usually 0.5 mm diam.

13. cernuus

Glumes obtuse, tip flat; stems erect usually 1-1.5 mm diam

Glumes acute, tip constricted beside keel; stems often drooping, < 0.5 mm diam.

Style-branches 3; nut trigonous

20. inundatus

Style-branches 2; nut plano-convex

23. sulcatus

Glumes 1-2 mm long; nut white or cream

22. reticularis

Glumes 0.5-1 mm long; nut grey to black

25. *chlorostachyus

Flowering usually occurs from October to February and fruit is ripe c. 2. months after flowering.

The genus has been variously divided into sections, many of which have been published as separate genera and are accepted as such by several authors.

Two specimens, Molesworth airstrip (CHR 73796), Lake Camp (CHR 92306), match the type of the Australian annual S. australiensis (Maiden and Betche) S. T. Blake in a number of character but the material is too meagre for a firm decision. Both specimens are small, tufted, apparently annual and a fuller description of them is given in Moore and Edgar Fl. N.Z. 2, 1970, 187.

Descriptions of native spp. are abbreviated; additional characters can be extracted from the key and synopsis.

I. Inflorescence terminal with several wide leaf-like bracts.

Fig. 31: SCIRPUS; A: S. setaceus, inflorescence, spikelets with single bract, A 1 nut showing longitudinal ribs. B: S. caldwellii, inflorescence, spikelets with several leaf-like bracts, B 1 nut. © All rights reserved. [Image: 26XI]

Scirpus L.

SYNOPSIS

Key

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