Acaena Mutis ex L.

Volume IV (1988) - Flora of New Zealand Naturalised Pteridophytes, Gymnosperms, Dicotyledons

ACAENA L.

(B.H.M.)

Perennial herbs or dwarf shrubs, often prostrate and forming large mats. Lvs imparipinnate; leaflets toothed; stipules adnate to petiole, persistent. Infl. terminal or axillary, capitate or spicate. Fls 3-5-merous, small, ⚥ or ♀. Hypanthium deeply concave, contracted at mouth. Epicalyx 0. Calyx of 3-5 sepals. Petals 0. Stamens 1-10. Ovary superior, surrounded by the hypanthium. Styles 1-2. Ovules 1-2. Fr. of 1-2 achenes enclosed in dry hypanthium bearing 4 or more, often barbed, spines, or without spines.

SYNOPSIS

A. Sect. ACROSTACHYA.
- Erect, forming clonal clumps. Infl. spicate. Fr. 20-70, ovoid; spines 10-55, covering fr., barbed. Styles and seeds 1-2:
- 1. * agnipila* echinata
B. Sect. PTERACAENA.
- Ascending or decumbent, not stoloniferous. Infl. a globular capitulum. Fr. > 100, compressed; spines 2, enclosed in wings, not barbed. Style and seed 1:
- 7. glabra
C. Sect. ANCISTRUM.
- Prostrate, stoloniferous. Infl. a globular capitulum. Fr. 40-130, obconic; spines 4, at apex of fr. (occasionally subsidiary spines below), barbed. Style and seed 1:
- 2. anserinifolia4. caesiiglauca5. dumicola6. fissistipula9. magellanica11. minor12. novae-zelandiae13. pallida14. profundeincisa15. saccaticupula
D. Sect. MICROPHYLLAE.
- Prostrate, rhizomatous. Infl. a globular capitulum, sometimes sessile. Fr. 2-20, turbinate; spines 0-4, at apex of fr., not barbed. Styles and seeds 2:
- 3. buchananii8. inermis10. microphylla

Key

Plant with main stems erect, forming tight clonal clumps, occasionally prostrate at base; fls in short spikes; infructescences elongating to interrupted spikes 10-30 cm long

Plant creeping with epigeal stolons, or with short decumbent branches, or of mat-forming tufts; fls and fr. arranged in globular, terminal heads

Spines of fr. ± equal, all lacking thickened conic bases; plant pilose to glabrate

1. *agnipila

Spines of fr. very unequal, the larger with thickened conic bases; plant glabrate with few appressed hairs

*echinata ζ

Plant glabrous, with slender, woody branches, spreading or erect; foliage bright green above, with reddish secondary colour; fr. compressed, with 2 wings, each enclosing a spine

7. glabra

Plant hairy, creeping with above ground stolons and ascending shoots terminating in scape or of mat-forming tufts; foliage green, glaucous, purplish, olive or bronze; fr. obconic or turbinate, with 4 protruding spines, or lacking spines

Plant stoloniferous with ascending shoots terminating in scapes; scapes usually > 5 cm long; stigma and ovule 1; fr. 40-130, obconic, with 4 spines; spines with retrorse barbs at tips

Plant of mat-forming tufts, with short prostrate branches quickly rooting; heads ± sessile, or scapes usually < 5 cm long; stigmas and ovules 2; fr. 2-20, turbinate, lacking spines, or with spines lacking retrorse barbs at tips

Leaflets green or brownish green above, paler or glaucescent below

Leaflets glaucous or dark purplish green on both surfaces

Distal leaflet length distinctly > width, with 7-15-(21) teeth; most stipules deeply divided; anthers and stigma white, or rarely rose, especially in subalpine plants

Distal leaflet length just > width, with (5)-9-11-(14) teeth; stipules little divided, with broad central lobe; anthers and stigma red

Upper leaflet surface dull; teeth obviously penicillate; florets c. 50-60; spines of fr. 4-9 mm long, rose or yellow-green when immature

2. anserinifolia

Upper leaflet surface shining; margins of teeth curved back to obscure hairs and give leaflet a crenate appearance; florets c. 80 or more; spines of fr. 7-20 mm long, red when immature

Stem 1-2 mm diam.; distal leaflet 4-20 mm long; leaflets smooth on upper surface, paler green, or occasionally subglaucous on lower surface; spine of fr. 7-12 mm long

12. novae-zelandiae

Stem 2-3 mm diam.; distal leaflet 6-30 mm long; leaflets with thick wrinkled cuticle on upper surface, pale with uneven wax layer on lower surface; spine of fr. 10-20 mm long

13. pallida

Plant slender, with stolon 1-1.5 mm diam.; leaflets 7-13, with teeth and lower leaflets red; fr. pilose, obconic; plant of subalpine to alpine E. South Is

14. profundeincisa

Plant robust, with stolon 2-4 mm diam.; leaflets 11-17, with purplish secondary colour; fr. glabrate, with dilated ribs; Macquarie Id

9. magellanica

Leaflets wedge-shaped; stigma and anthers red; fr. glabrous or sparsely hairy, with dilated ribs; spines < 4 mm long

15. saccaticupula

Leaflets suborbicular, oblong, or obovate; stigma and anthers white or red; fr. pilose; ribs not dilated; spines > 4 mm long

Distal leaflets suborbicular

Distal leaflets oblong or obovate, or at least with length > width

Three distal leaflets distinctly larger than lower leaflets; leaflets with silky appressed hairs below, the teeth slightly penicillate and red-brown when coloured; stipules entire or 2-3-(5)-fid; scapes 7-10 cm long, pale red-brown; stigma and anthers white

5. dumicola

Leaflets ± evenly reduced in size towards base of lf; leaflets sparsely pilose below, the teeth distinctly penicillate and grey-brown when coloured; stipules deeply (3)-4-5-fid; scapes 12-20 cm long, often purplish; stigma and anthers red

6. fissistipula

Leaflets glabrous above, with marginal hairs of lower surface conspicuous giving leaflet a white-fringed appearance, lacking red secondary colour; scapes 0.5-7 cm long; stigma white; anthers red; Subantarctic Is

11. minor

Stems 10-50 cm long; lvs 5-15 cm long; leaflets 9-15; spines of fr. yellow

var. antarctica

Stems < 5 cm long; lvs < 2 cm long; leaflets 7-9; spines of fr. red

var. minor

Leaflets moderately to densely pilose above and below, often with red secondary colour; scapes (2)-4-20 cm long; stigma white, rose or red; anthers white or red; mainland N.Z.

Leaflets glaucous above and below, with upper surface rugose; lower ⅓ of margin of most leaflets entire; scapes (7)-20 cm long; stigma and anthers white

4. caesiiglauca

Leaflets subglaucous or grey above, glaucous below, with upper surface smooth; margin of most leaflets toothed to base; scapes (2)-4-12 cm long; stigma rose; anthers red

14. profundeincisa

Lvs 0.5-3 cm long; leaflets green or bronze above, with cuticle shining

10. microphylla

Fruiting heads held above foliage on scapes < 2 cm long; fr. c. 20, usually with crimson spines radiating to form a conspicuous ball; spines without barbs or hairs

var microphylla

Fruiting heads hidden among lvs; fr. 2-4, with pale red spines bearing a few stiff hairs at tip or naked

var pauciglochidiata

Lvs 1.5-9 cm long; leaflets glaucous, purplish, pale to dark olive-grey, or milky green, not shining

Leaflets glaucous, purplish, or olive-brown; scapes 1-5-(7) cm long; fr. c. 20, not armed, or bearing 4 red spines without barbs

8. inermis

Leaflets milky green or olive-grey; capitula sessile; fr. c. 10, bearing 4 yellow or red spines with soft hairs at tips

3. buchananii

c. 100 spp., mostly S. Hemisphere, extending to Hawaii and California. Native spp. 14, naturalised 2.

The most comprehensive monograph of the genus is that of Bitter, G., Biblioth. Bot. (Stuttgart) 74: 1-336 (1910-11). Allan (1961) recognised 15 native spp. in N.Z. The N.Z. spp. are currently under revision. Orchard, A. E., Trans. Roy. Soc. South Aust. 93: 91-109 (1969) and Rec. Auck. Inst. Mus. 10: 97-107 (1973), has revised the A. ovina group, but there has been no overall revision of the Australian spp. A prominent feature of many Acaena spp. is the presence of barbed spines on the mature hypanthium. These aid in dispersal as the individual frs easily become detached when animals brush against them. Not only does this allow Acaena to disperse readily but also the fr. are retained in wool and clothing. In N.Z. the native spp. are commonly called piripiri (piri means to stick, cling) corrupted to bidibid.

Acaena Mutis ex L.

SYNOPSIS

Key

Volume contents

Share