Trifolium L.

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

TRIFOLIUM L.

Annual to perennial, procumbent to erect herbs. Lvs palmately or pinnately 3-foliolate (rarely 5-9-foliolate, but not in N.Z. spp.); principal lateral veins terminating at leaflet margin often in a tooth; stipules adnate to petiole. Infls axillary or terminal, racemose, umbellate, or spicate, few- to many-flowered (if many-flowered then fls usually forming dense heads); bracts present, 0, or reduced to glandular hairs. Calyx teeth 5, usually subequal or the lower longer. Corolla usually persistent after flowering. Vexillary filament free, the others united into a sheath split adaxially; anthers uniform. Style glabrous; stigma capitate or hooked. Pod 2-valved, ± straight, usually indehiscent, very rarely dehiscent, not armed, 1-2-(10)-seeded; seeds estrophiolate, smooth and rounded.

SYNOPSIS

The synopsis is based on Zohary, M. and Heller, D., The Genus Trifolium (1984).

A. Sect. CHRONOSEMIUM
- Fls ebracteate or with minute bracts or bracts reduced to glandular hairs, all with corollas and mostly fertile. Calyx 5-veined, unchanged at fruiting; throat glabrous and open at fruiting. Pod 1-2-seeded:
- 3. * aureum4. * campestre6. * dubium13. * micranthum
B. Sect. LOTOIDEA.
- Fls mostly bracteate, all with corollas and mostly fertile. Calyx usually 10-veined, not or slightly changed at fruiting; throat glabrous and open at fruiting. Pod 1-10-seeded:
- 5. * cernuum8. * glomeratum10. * hybridum15. * ornithopodioides17. * repens19. * retusum23. * suffocatum
C. Sect. TRICHOCEPHALUM.
- Fls ebracteate, mostly without corollas and sterile, a few outer fls with corollas and fertile. Calyx of sterile fls of a solid tube and long bristly teeth, concealing fertile fls at maturity. Pod 1-seeded:
- 22. * subterraneum
D. Sect. TRIFOLIUM.
- Fls ebracteate, all with corollas and mostly fertile. Calyx 10-20-veined, not or slightly changed at fruiting; throat usually closed by a ring of hairs or callosity at fruiting. Pod 1-(2)-seeded:
- 1. * angustifolium2. * arvense9. * hirtum11. * incarnatum12. * medium14. * ochroleucon16. * pratense20. * scabrum* squarmosum21. * striatum
E. Sect. VESICARIA.
- Fls bracteate, all with corollas and mostly fertile. Calyx 10-veined, greatly inflated, and hairy and veined on one side at fruiting; throat narrowed or closed at fruiting. Pod 1-2-seeded:
- 7. * fragiferum18. * resupinatum24. * tomentosum

Key

Corolla white, pink, red or purple, 2-18 mm long, if yellowish then > 10 mm long; bracts subtending fls present or 0 but not reduced to glandular hairs

Corolla yellow and < 7 mm long; bracts subtending fls reduced to glandular hairs

Lvs glabrous or occasionally sparsely hairy about petiolules and on undersurface of leaflets; leaflets never linear-lanceolate; bracts subtending fls present, sometimes connate at base of infl.

Lvs moderately to densely hairy (particularly on petiole and undersurface of leaflets), if only sparsely hairy then leaflets long linear-lanceolate; bracts subtending fls 0, but in some spp. infl. subtended by connate bracts or stipules of subtending lvs at base

Calyx glabrous or sparsely hairy at flowering, not inflated at fruiting

Calyx densely hairy on upper side at flowering, greatly inflated on upper side at fruiting

Corolla 5-12 mm long; perennial with numerous fls per infl. or if annual then infls 1-5-flowered; calyx teeth spreading to erect at fruiting

Corolla 2-5 mm long; annual with usually numerous fls per infl., rarely as few as 6; calyx teeth recurved at fruiting

Leaflets usually obtriangular, rarely obovate; infls 1-3-(5)-flowered

15. *ornithopodioides

Leaflets elliptic to obovate or suborbicular; infls with numerous fls

Calyx teeth < tube, and sinuses acute; stems rooting at nodes; corolla usually white, occasionally pink to reddish

17. *repens

Calyx teeth > tube, and sinuses obtuse; stems not rooting at nodes; corolla usually pink

10. *hybridum

Fls becoming recurved at fruiting; heads mostly pedunculate

Fls remaining ± erect at fruiting; heads usually sessile, sometimes pedunculate

Pedicels c. 2 mm long; peduncles < 0.5 mm diam.

5. *cernuum

Pedicels up to 1 mm long at fruiting but fls usually subsessile; peduncles 0.75-1 mm diam.

19. *retusum

Infls densely crowded on short stems; calyx teeth < corolla, slightly recurved at fruiting

23. *suffocatum

Infls mostly remote; calyx teeth < corolla, strongly recurved at fruiting

8. *glomeratum

Perennial; stems rooting at nodes; calyx teeth unequal at flowering; lvs usually elliptic, sometimes ovate or obovate; petioles up to 100 mm long

7. *fragiferum

Annual; stems not rooting at nodes; calyx teeth ± equal at flowering; lvs obovate to obtriangular; petioles 5-30 mm long

Corolla 3-4 mm long; 2 upper calyx teeth inconspicuous on the inflated, lanate calyx at fruiting

24. *tomentosum

Corolla (4)-5-7 mm long; 2 upper calyx teeth conspicuous on the inflated, moderately hairy calyx at fruiting

18. *resupinatum

Infl. with 2-5-(7) fertile fls, and central sterile fls with enlarged calyx at fruiting

22 *subterraneum

Infl. with 7-numerous fls and all fertile

Infls all terminal; corolla 5-18 mm long

Infls axillary, or axillary and terminal; corolla 3-5 mm long

Infls ovoid, globose or shortly cylindric

Infls mostly long-cylindric, sometimes ovoid or short- cylindric when immature

Corolla 5-9 mm long

*squamosum ζ

Corolla 10-18 mm long

Corolla white, cream or pale yellow

Corolla pink to reddish purple

Lowermost calyx tooth 2-3× as long as other 4; lvs moderately to densely hairy on both surfaces

14. *ochroleucon

Lowermost calyx tooth 11/2-2× as long as other 4; lvs moderately hairy on lower surface but almost glabrous or sparsely hairy on upper

16. *pratense

Calyx 20-veined; calyx teeth subequal; annual

9. *hirtum

Calyx 10-veined; lowermost calyx tooth distinctly longer than other 4; perennial

Infls usually sessile; calyx teeth triangular with linear apex

16. *pratense

Infls pedunculate, particularly at fruiting; calyx teeth linear

12. *medium

Leaflets linear-lanceolate, acute to acuminate; lowest calyx tooth longer than other 4 and just < or ± = corolla

1. *angustifolium

Leaflets obovate, obtuse to slightly emarginate or slightly acute; lowest calyx tooth ± = other 4 and < corolla

11. *incarnatum

Infls pedunculate

2. *arvense

Infls sessile

Lateral veins of leaflets recurved and thickened toward leaflet margin; corolla white; calyx teeth spreading at fruiting

20. *scabrum

Lateral veins of leaflets thin and straight to leaflet margin; corolla pink; calyx teeth erect at fruiting

21. *striatum

Petiolules distinctly unequal, terminal much > lateral; lvs glabrous to moderately hairy

Petiolules all ± equal; lvs ± glabrous

Infls 5-20-(25)-flowered; lower calyx teeth ± = or somewhat > tube; corolla 2.5-4 mm long .

6. *dubium

Infls 20-40-flowered; lower calyx teeth much > tube; corolla 3.5-5 mm long

4. *campestre

Corolla 6-7 mm long; infls with numerous fls; pedicels c. 0.5 mm long

3. *aureum

Corolla 2-3 mm long; infls 1-7-flowered; pedicels 0.5-1.5 mm long

13. *micranthum

237 spp., Eurasia, Africa, N. and S. America. Naturalised spp. 25.

Several Trifolium spp. are important as pasture plants, and some are also important in honey production. Most naturalised spp. are escapes from cultivation or are weeds often established from seed impurities. Plate 13 illustrates flowering or fruiting heads for spp. from all sections of the genus. Almost all naturalised N.Z. spp. are illustrated in Healy, A. J., Identification of Weeds and Clovers ed. 3 (1982).

A number of clover spp. are reported to be poisonous (Connor 1977), in particular the effect of hydrocyanic acid poisoning from T. repens has been closely investigated.

Trifolium L.

SYNOPSIS

Key

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