Flora of New Zealand Series

Annual, or perennial, often rhizomatous herbs. Stems leafy at base or leaves reduced to basal sheaths. Inflorescence umbellate or capitate, surrounded by 1-several leaf-like involucral bracts. Spikelets compressed or subterete, 1-many-flowered, usually clustered in spikes at tips of rays or in a sessile spike. Flowers hermaphrodite. Glumes distichous, usually all fertile. Hypogynous bristles 0. Stamens 2-3, or 1. Style 2-3-fid, continuous with ovary, not thickened at base. Nut trigonous or biconvex. A tropical and warm temperate genus of c. 550 spp., one endemic in N.Z.; 13 adventive.

Spp. in N.Z. may be referred to the following subgenera -

• A. Subgenus CYPERUS. 
• • Style-branches 3, nuts trigonous; spikelets with deciduous glumes but rhachilla persistent on rhachis of spike:
  • 1. *albostriatus, 4. *eragrostis, 5. *esculentus, 7. *involucratus, 9. *longus, 11. *rotundus, 13. *tenellus
• B. Subgenus MARISCUS. 
• • Style-branches 3, nuts trigonous; spikelets occasionally with deciduous glumes and rhachilla deciduous from rhachis of spike just above an elevated scar-like base:
  • 3. *congestus, 6. *gunnii, 14. ustulatus
• C. Subgenus KYLLINGA. 
• • Style-branches 2, nuts biconvex; spikelets 1-flowered, deciduous intact from rhachis of spike:
  • 2. *brevifolius, 8. *kyllingia
• D. subgenus PYCREUS. 
• • Style-branches 2, nuts biconvex; spikelets several-flowered with deciduous glumes but rhachilla persistent on rhachis of spike:
  • 10. *polystachyos, 12. *sanguinolentus

Key

1

Rhizomes evident, spreading, tubers present or absent

2

Rhizomes absent, or very short and thick, tubers absent but stem bases often ± swollen

7

2

Inflorescence a single globose whitish-green head

3

Inflorescence umbellate, green- or yellow-brown to red-purple

4

3

Keel of glumes winged

8. *kyllingia

Keel of glumes not winged

2. *brevifolius

4

Rhizomes with tubers, slender

5

Rhizomes without tubers, thick, ± 5-10 mm diam

6

5

Tubers along rhizomes; spikelets red-to purple-brown

11. *rotundus

Tubers terminal on rhizomes; spikelets yellowish-brown

5. *esculentus

6.

Leaves with conspicuous white veins; involucral bracts ± equal

1. *albostriatus

Leaves lacking white veins, involucral bracts dissimilar in length

9. * longus

7

Leaf-laminae with evident minute transverse septa between veins

8

Leaf-laminae lacking minute transverse septa; or leaves reduced to basal sheaths

9

8

Leaf-margins and midrib below, harshly serrate; spikelets in dense oblong spike 3-5cm long

14. * ustulatus

Leaf-margins and midrib sparsely scabrid; spikelets in ± loose hemispherical spikes to 2 cm long

6. *gunnii

9

Spikelets narrow-linear (8)-10-20 × 1-2 mm, chestnut-brown to red-purple

10

Spikelets ovoid to oblong, 3-8-(12) × 2-3 mm, green, yellow-green, brownish-green or red-purple to black

11

10

Spikelets reddish-purple; minute transverse septa evident on leaf-sheaths; style-branches 3

3. *congestus

Spikelets chestnut-brown; minute transverse septa few or absent on leaf-sheaths; style-branches 2

10. *polystachyos

11

Plants obviously leafy; involucral bracts several, foliaceous, unequal in length

12

Plants with few filiform leaves or with leaves reduced to sheaths; involucral bracts 1-(2), setaceous or several foliaceous and ± equal

13

12

Leaves broad, 4-8 mm wide, margins finely serrate; spikelets light green to yellow-green

4. *eragrostis

Leaves narrow, to 2.5 mm wide, margins smooth except near tip; spikelets dark red-purple to black

12. *sanguinolentus

13

Inflorescence with solitary (rarely 2) setaceous bracts; plants small, stems and leaves filiform

13. *tenellus

Inflorescence with many foliaceous bracts; plants large, stems stout, leaves reduced to basal sheaths

7. * involucratus

The best known sp. is C. papyrus (Egyptian paper plant or papyrus), occasionally planted about ponds and water garden in N.Z., but not yet found wild here. A limited range of others are used here and overseas, as horticultural subjects, planted about aquaria and ponds, several often erroneously sold and planted as papyrus. A number of spp. with rhizomes and tubers are serious weeds of cultivation in tropical and temperate regions. The characteristic inflorescences with foliaceous bracts radiate below the umbels are responsible for the several common names applied in horticulture - star grass, star sedge, umbrella grass, umbrella palm, umbrella plant, and umbrella sedge.

Fig. 30. CYPERUS. inflorescence; A: C. tenellus, showing distichous arrangement of glumes (characteristic of Cyperus) and a single bract, × 4. B: C. involucratus, showing several ± equal involucral bracts × 2/5. C: C. congestus, × ⅔. D: C. eragrostis, × ⅔. © All rights reserved. [Image: 26XH]