Juncus L.

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

JUNCUS L.

Annual or perennial herbs, tufted or rhizomatous, glabrous. Leaves flat and grass-like, or tubular or laterally compressed with internal septa, or channelled, or terete and stem-like, or reduced to basal sheaths. Inflorescence a many-flowered cyme, much-branched or condensed to a compact head, or flowers rarely few or solitary. Flowers usually hermaphrodite, sessile or pedicellate. Tepals 6, rarely 4, lanceolate, the outer usually longer, slightly more rigid with narrow membranous margin, inner with broader membranous margin. Stamens 6, 3, or variable 3-6. Ovary unilocular, or triseptate, or trilocular. Seeds numerous, often tailed at one or both ends. A cosmopolitan genus of c. 300 spp. Native spp. 16, adventive 31.

SYNOPSIS

A. Sect. POIOPHYLLI:
- Plant tufted or rhizomatous; stems usually leafy, rarely only basal sheaths present; leaves flat or channelled, rarely cylindrical; inflorescence terminal:
- 1. *ambiguus, 2. *bufonius, 3. *dichotomus, 4. *gerardii, 5. *homalocaulis, 6. *imbricatus var. chamissonis, 7. *squarrosus, 8. *tenuis
B. Sect. GENUINI:
- Plant rhizomatous; stems with no true leaves and only basal sheaths; inflorescence apparently lateral
- (a)
- - Stems light-, bright- or dark green, or red-brown, usually shining, smooth:
  - 10. *conglomeratus, 11. *continuus, 12. *effusus, 14. *flavidus, 16. *procerus, 18. australis, 19. distegus, 20. gregiflorus, 21. pallidus, 22. pauciflorus
- (b)
- - Stems blue-green or light green, dull, ridged:
  - 9. *amabilis, 13. *filicaulis, 15. *inflexus, 17. *subsecundus, 23. sarophorus, 24. usitatus
C. Sect. THALASSII:
- Plant rhizomatous; stems with 1-2 terete, green leaves as well as basal sheaths; inflorescence apparently lateral:
- 25. *acutus, 26. maritimus var. australiensis
D. Sect. SEPTATI:
- Plant tufted or rhizomatous; stems with transversely-septate leaves, both basal and cauline, sheaths with obtuse auricles; inflorescence terminal:
- 27. *acuminatus, 28. *acutiflorus, 29. *articulatus, 30. *brachycarpus, 31. *bulbosus, 32. *canadensis, 33. *ensifolius, 34. *fockei, 35. *microcephalus, 36. *subnodulosus, 37. holoschoenus, 38. novae-zelandiae, 39. prismatocarpus, 40. pusillus, 41. scheuchzerioides
E. Sect. GRAMINIFOLII:
- Plant tufted; stems with many basal non-septate leaves, sheaths without auricles; inflorescence terminal:
- 42. *capitatus, 43. *dregeanus, 44. *lomatophyllus, 45. antarcticus, 46. caespiticius, 47. planifolius

Key

Leaves many, flattened, channelled, tubular or filiform; inflorescence terminal and appearing so

Leaves 1-2 cylindrical like the stem, or all reduced to basal sheaths; inflorescence apparently lateral

Leaves ± compressed, hollow with internal septa; plant usually rhizomatous

§ SEPTATI

Leaves solid, without internal septa; plant usually tufted

Capsule distinctly > tepals

Capsule ± = or < tepals

Leaves hollow, ± compressed, not setaceous, or flat and ensiform

Leaves setaceous, or flat and ensiform

Flower-clusters dark brown c. 5 × 4 mm or smaller

Flower-clusters reddish-green from 7 × 5 mm to 10 × 10 mm

Plants loosely or densely tufted with slender rhizomes; capsules dark brown to nearly black

29. *articulatus

Plants with stout, far-extending rhizomes, not tufted; capsules red-brown

28. *acutiflorus

Leaves unitubular, with transverse septa extending across whole leaf-width; stamens 6

34. *fockei

Leaves multitubular, with transverse septa extending across individual tubes; stamens 3

39. *prismatocarpus

Plants to 70 cm high; leaves ensiform, ± flat

33. *ensifolius

Plants low-growing, 2.5-15- (25) cm high; leaves setaceous, very narrow

Capsule black, shining; inflorescence without tufts or setaceous leaves

38. novae-zelandiae

Capsule yellow-brown; inflorescence usually with tufts of setaceous leaves

31. *bulbosus

Leaves hollow, ± compressed, not setaceous, septa clearly visible externally

Leaves setaceous, septa scarcely visible externally

Upper part of stems below inflorescence with obvious internal transverse septa; stamens usually 3

Upper part of stems below inflorescence without transverse septa; stamens 6

Individual flower-clusters with 2 subtending bracts > flowers

30. *brachycarpus

Individual flower-clusters without longer subtending bracts

Seeds with distinct tails at each end

32. *canadensis

Seeds without tails

27. *acuminatus

Capsule 2.5-3.5 mm long, broad, depressed at top, minutely mucronate

35. *microcephalus

Capsule c. 4.5 mm or < 2.5 mm long, slightly tapered or acuminate

Rhizome slender, short; tepals acuminate, not incurved; capsule c. 4.5 mm long

37. holoschoenus

Rhizome stout, far-extending; tepals blunt, incurved; capsule < 2.5 mm long

36. *subnodulosus

Inflorescence frequently with tufts of setaceous leaves; stems slender, rooting, nodes swollen; plants occasionally aquatic

31. *bulbosus

Inflorescence without tufts of setaceous leaves; stems thick, rooting, nodes not swollen, or long rhizomes present; plant terrestrial

Capsule c. 2 mm long; leaves filiform, < 0.5 mm wide

40. pusillus

Capsule c. 4 mm long; leaves > 0.5 mm wide

41. scheuchzerioides

Flowers in many-flowered globose clusters or a single ovoid head

§ GRAMINIFOLII

Flowers borne singly and evenly along inflorescence-branches or grouped in small clusters of (1) -2-3- (7), not in a single head

§ POIOPHYLLI24

Inflorescence umbel-like, with few to numerous flower-clusters at tips of spreading branches; leaves ± flat

Inflorescence a single flower-cluster (occasionally a second or third cluster above it); leaves setaceous or channelled

Flower-clusters c. 5 mm diam.; capsules c. 2 mm long

47. planifolius

Flower-clusters c. 10 mm diam.; capsules 2.5-3 mm long

Leaves 6-15 mm wide; inflorescence with many spreading branches

44. *lomatophyllus

Leaves 1.5-4 mm wide; inflorescence sparingly branched

43. *dregeanus

Plant 15-30 cm high

46. caespiticius

Plant 2.5-8-(15) cm high

Tepals usually black, c. 3 mm long, ± = capsules

45. antarcticus

Tepals reddish, 4-5 mm long, much > capsules

42. *capitatus

Leaves soft, setaceous; inflorescence usually ⅔ length of whole plant, or composed of 1- (2) flowers; plant annual, readily pulled from soil

Leaves ± wiry, channelled, or tough and flat; inflorescence c. ¼ length of whole plant, not single-flowered; plant perennial, difficult to pull from soil

Plant > 2.5 cm high; inflorescence few- to many-flowered

2. *bufonius

Plant < 2 cm high; inflorescence a solitary flower, rarely a second flower present

1 *ambiguus

Auricles large, tongue-like, 2-4 times as long as broad; leaves flat

8. *tenuis

Auricles short, gradually rounded and following curve of top of sheath; leaves rolled or channelled

Plants with black, far-extending rhizomes, of saline soils; outer tepals hooded at tip

4. *gerardii

Plants tufted, sometimes with short rhizomes, of acid bogs and non-saline swampy to drier soils; outer tepals subulate, or acute to acuminate

Leaves noticeably crowded at stem-base, abruptly reflexed from just above wide sheath; plants of acid bogs

7. *squarrosus

Leaves not obviously crowded at stem-base, erect or ± drooping but not abruptly reflexed, sheath scarcely wider than lamina; plants or various situations, not acid bogs

Capsule 6-6.5 mm long, much > tepals; tepals appressed to mature capsule

6. *imbricatus var. chamissonis

Capsule 3-5 mm long, ± = or < tepals; tepals spreading from mature capsule

Flowers evenly dispersed along inflorescence-branches; capsules ± 3mm long

3. *dichotomus

Flowers in clusters of 2-6, c. 3 clusters in one inflorescence; capsules ± 5 mm long

5. *homalocaulis

Leaves 1-2, cylindrical like stem; plant usually of coastal saline flats

§ THALASSII

Leaves all reduced to sheathing bracts at base of stem; plant of non-saline soils

§ GENUINI33

Inflorescence open, flowers in small clusters; capsules dark brown, ± = tepals

26. maritimus var. australiensis

Inflorescence dense, large, clusters a compact mass; capsules red-brown, much > tepals

25. *acutus

Flowers in clusters at ends of inflorescence-branches or in a single dense cluster

Flowers evenly dispersed along inflorescence-branches

Inflorescence open, much-branched, many-flowered, or condensed but wider than 1.5 cm

Inflorescence a single congested cluster c. 1 cm wide, often with 1-2-(4) few-flowered lateral clusters

Capsules 1.5-2-(2.3) mm long; stems bright green

Capsules 2-3.5 mm long; stems dull blue-green, or yellow-, grey-, or light green

Pith interrupted, rarely continuous, bright white, dense; capsule < or ± = tepals

20. gregiflorus

Pith continuous, greyish-white, cobwebby; capsule > tepals

11. *continuus

Stamens 6; stems light green, pith continuous

21. pallidus

Stamens 3-4, rarely more in occasional flowers; stems yellow-green or blue-green, pith interrupted, rarely continuous

Basal sheaths shining red-brown below; capsules with obtuse top

Basal sheaths either very dark purple-red or dull brown below; capsules with either subacute or flattened top

stems blue-green, pith almost completely lacking, occasionally continuous

18. australis

Stems yellow-green, pith interrupted by ± regular cavities

14. *flavidus

Stems 3.5-8 mm diam., yellow-green, soft; basal sheaths very loose, dull brown to dark reddish

16. *procerus

Stems (1) -1.5-2.5 mm diam., hard; basal sheaths closely appressed, dark red-purple

9. *amabilis

Pith continuous, or interrupted in an irregular pattern by rather large cavities; stems usually > 1.5 mm diam.

Pith interrupted in a regular pattern by small cavities; stems < 1.5 mm diam.

Stems wiry, difficult to break; pith interrupted or continuous but not cobwebby

20. gregiflorus

Stems soft, easily broken; pith continuous, cobwebby

Sheathing base of bract subtending inflorescence narrow, green; stems not ridged, bright green

12. *effusus

Sheathing base of bract subtending inflorescence widely expanded, red-tinged; stems ridged above, dull blue-green

10. *conglomeratus

Inflorescence of 2- (4) clusters, the upper stalked, lower sessile; capsules usually > tepals; stems 0.75-1.5 mm diam., dull- or red-green

19. distegus

Inflorescence usually a single cluster; capsules ± = tepals; stems 0.5-1 mm diam., blue- or grey-green

13. *filicaulis

Lower branchlets of inflorescence curved downwards; stems soft, easily broken

12. *effusus

Lowers branchlets of inflorescence erect or spreading but not down-curved; stems wiry or soft

Basal sheaths dark red-purple almost black below; inflorescence dense, fan-shaped, appressed to subtending bract, or diffuse with dark purple-brown capsules

Basal sheaths light green to pinkish-brown or reddish-brown; inflorescence diffuse, capsules greenish-brown or light brown to red-brown

Inflorescence dense, fan-shaped, appressed to subtending bract; capsules light brown, 1.5-2 mm long

23. sarophorus

Inflorescence diffuse, not appressed; capsules dark purple-brown, 2.5-3.5 mm long

15. *inflexus

Pith continuous; stamens 6

Pith usually interrupted, occasionally continuous; stamens usually 3

Stems 3-8 mm wide, light green, soft

21. pallidus

Stems < 2mm wide, dark green, wiry

22. pauciflorus

Capsule < 2 mm long; stems light green

24. usitatus

Capsule > 2 mm long; stems blue-green

17. *subsecundus

Most spp. flower between November and January, and seed is set from January to February.

The leafless species (sect. Genuini) with their easily recognised habit - woody rhizomes, dense clumps of erect, rigid, ± cylindrical, acute-tipped stems with mucronate basal sheaths, and apparently lateral heads - are known by the Maori name "wiwi" and the standard common name "rushes".

In the field, the name "rushes" is applied in a broad sense to include a number of plants with this characteristic habit, which belong to related families. Many such plants are commonly confused, especially in the non-flowering state, with the true rushes, and include spp. of Baumea, Eleocharis, Lepidosperma, Schoenus, Scirpus and Tetraria (Cyperaceae), and Empodisma (Calorophus) and Leptocarpus (Restionaceae). These have been keyed out, on vegetative characters, in Healy, Identification Weeds & Clovers 1976, 130-137.

The septate-leaved spp. (sect. Septati) are distinctive, and cannot be confused with plants of any other monocotyledonous group. The non-septate and grassy-leaved spp. (sect. Poiophylli, sect. Graminifolii) may be, and are often confused with grasses (Gramineae) and sedges (Cyperaceae - Carex, Scirpus); the tabulation should assist in differentiating members of the three families:

Spp.of Juncus have a preference for, and are often characteristic of damp to swampy habitats, but this is not invariable. Both leafy and leafless spp. can establish successfully in bared sites on dry soils where there is little competition.

The reaction of leafless rushes to chemical herbicides merits mention: spp. with entire cobwebby pith and soft, green, non-ridged stems are most susceptible, while those lacking pith or with much interrupted pith and hard, blue-green, strongly ridged stems are resistant or only slightly susceptible. Spp. With dense pith - entire or interrupted by cavities - and wiry ridged or non-ridged stems are intermediate in susceptibility.

Character	Juncaceae	Cyperaceae	Graminae
Leaf arrangement	in three rows	usually in three rows	in two rows
Leaf sheath	split or not split	never split	split or not split
Leaf lamina	if present, flat, folded or rolled: margins smooth: reduced to basal sheaths in sect. Genuini	usually folded: margins rough	flat, folded or rolled: margins smooth or rough
Ligule	absent	partially fused to upper surface of lamina	not fused to upper surface of lamina: rarely absent
Auricles	present or absent	absent	present or absent
Stem	round to ± compressed, solid or with pith, smooth: nodes not conspicuous	usually 3-angled occasionally round solid or with pith: angles often rough: nodes not conspicuous	round to ± compressed, usually hollow: nodes solid often conspicuous
Flowers	tepals in two whorls	without evident calyx and corolla each in axil of 1 bract, the glume	without evident calyx and corolla, each within 2 bracts, lemma and palea
Stamens	anthers basifixed	anthers basifixed	anthers dorsifixed
Fruit	a 3-locular, 3-many-seeded capsule	a nut	a caryopsis

Fig. 16. JUNCUS. A-D; diagrammatic habit drawings showing characteristics of sections. E-G: diagrams of portion of leaf; E: flat leaf, sections Graminifolii and Poiophylli. F-G: two different kinds of septate leaf, section Septati. © All rights reserved. [Image: 26X1]

Fig. 17. JUNCUS sect. Genuini; some forms of inflorescence, × ½. Compact head; J. conglomeratus (bract-base wide), J. effusus. Flowers evenly dispersed; J. inflexus, J. effusus (lower branches drooping). Flowers in clusters; J. gregiflorus, J. amabilis. © All rights reserved. [Image: 26X2]

Fig. 18. JUNCUS; inflorescences × ⅔. Section Poiophylli, flowers borne singly; sections Septati and Graminifolii, flowers in narrow, or in rounded clusters. © All rights reserved. [Image: 26X3]

Juncus L.

SYNOPSIS

Key

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