Tuatara: Volume 6, Issue 1, January 1956
Key to the Genera of Cyperaceae in New Zealand
Key to the Genera of Cyperaceae in New Zealand
The cyperaceae or sedge family is one of the largest families of flowering plants, variously estimated at up to 80 genera and 3,000-4,000 species. Of universal distribution, it is found in all latitudes and climates from sub-polar regions to the equator and from seashore to alpine meadow. Far from being a family of swamp-dwellers as is usually supposed, it is represented in an astonishing range of habitats, in fact, almost any in which flowering plants will grow. Although the sedges reach their greatest luxuriance in swamps or river-flats and can always be relied upon to occur in such localities, they must not be regarded as confined to such areas. Coastal sand-dunes and beaches, fields, dense forest, scrub and fellfield each have their representatives, many of which are endemic to the particular habitat.
It will be seen then that there is a necessity, in almost any ecological or vegetational study, for a knowledge of the group.
Many elements of the New Zealand sedge flora are of interest from the geographical viewpoint and have a strong bearing on the question of the origin of the flora. Although this is not the place to discuss this question it will be of interest to note that there is a strong affinity with Australia, many species apparently common to the two areas, another with Polynesia and the Indo-Malaysian area, mainly at the generic and subgeneric level, and other relationships, less strong, with South America and South Africa. While acknowledging the influence of these areas, the incidence of endemism must be borne in mind. Many of the genera, and certainly those with more than four New Zealand representatives, have at least some species confined to New Zealand especially in Gahnia, Uncinia and Carex. It appears possible, for instance, that more than half of the species of Uncinia, a little-understood genus, are confined to New Zealand. In Carex a very large proportion of the species are endemic, whole sections of this cosmopolitan genus having apparently evolved within the boundaries of these shores.
Economically, the family is comparatively unimportant except where certain species occur as weeds of cultivated land. In New Zealand this is generally on poorly drained acid soils and a correction of these conditions is usually all that is necessary to gain control. A few species had importance in the culture of certain peoples, e.g. papyrus (Cyperus papyrus Linn.) in ancient Egypt. Tiger nuts or Zulu nuts, the tubers of Cyperus esculentus page 28 Linn., are used for food in certain parts of the world such as Africa and Asia, while the leaves and stems of various sedges are still used by many peoples for thatching, mat-making, basketwork, etc.
The flower is usually regarded as being derived from a typically trimerous form. Each flower is in the axil of a glume and may or may not be surrounded by a perianth. When present the perianth may be of 3-many parts which are scale-like (Oreobolus) (Fig. 34), filamentous (Scirpus (Fig. 26), Eleocharis (Fig. 22)), plumose (Carpha) (Fig. 37) or thick and fleshy (Lepidosperma) (Fig. 24). Other forms are present in overseas species and genera. The stamens are usually (1-)3-6 in number. Some species exhibit a peculiar habit, especially Gahnia and Cladium, in which the glume-margins curl and become involuted near the apex, firmly clasping the filaments just below the anthers; the filaments elongate, sometimes to many times the length of the flower, while remaining attached to the base of the fruit so that the latter in falling from the glume is held suspended from the spikelet (Fig. 45). The fruit is a one-seeded nut (as distinct from the caryopsis of grasses) and may be 2-angled (lenticular), 3-angled (trigonous) or many-angled depending on whether the ovary has 2, 3 or more style-branches respectively.
Structure Of The Spikelet
In the sub-families Cyperoideae and Scirpoideae, the spikelet is regarded as a simple racemose form with sessile flowers arranged in a spiral or distichous manner on the rachis. This appears to be the basic type for the family but the sub-families Rhynchosporoideae and Caricoideae exhibit important and characteristic modifications. In the former, the flowers are formed sympodially, i.e. each flower is terminal on the shoot and surrounded by its subtending glume; the rachilla is axillary to this glume and is produced between the glume and its flower; the rachilla then produces another terminal flower and the process is repeated. The effect of this is to make the flower appear not axillary to its glume but opposite it, with the rachilla between the two. As a result the flower usually appears, on casual examination, to be associated with what is morphologically the node below it, particularly if the rachilla is short and the glumes and flowers crowded. The condition is best seen in Schoenus pauciflorus where the rachilla is long and the flowers separated (Fig. 39b).
In Mariscus ustulatus, the base of each primary branch of the inflorescence is surrounded by a ‘sleeve’-like structure known as the prophyll. If each branch was reduced to a single flower and the rachis so reduced that it did not carry the fertile parts beyond the prophyll then a condition would be reached very much resembling the female flowers of the sub-family Caricoideae. The ‘utricle’ in Carex and Uncinia is considered to be a prophyll at the base of a one-flowered spikelet. page 29 Examination of an Uncinia fruit (Figs. 19, 20) offers substantiation. The ‘hook’ is a rachilla arising from below the flower and sharply reflexed at the first node. Occasionally aberrant flowers are found in which the rachilla, instead of forming a hook, produces one or more glumes with or without male flowers. On this interpretation, it is now customary to refer to the inflorescence of Carex and Uncinia as being composed of one-flowered female spikelets with one or more many-flowered male spikelets. In these two genera, the structure which Cheeseman, using the old nomenclature, describes as a ‘female spikelet’ must now be referred to as a ‘female spike’. The glumes of Uncinia and Carex are therefore morphologically equivalent to the foliar bracts of, say, Mariscus. (Mariscus is cited merely as a readily-observed example and does not carry the implication that this genus or group should be considered the ancestral form of the Caricoideae. Authorities generally look to the Rhynchosporoideae for the progenitors of the sub-family.)
A-B, a hypothetical type of flower with the basic floral formula of the family. This is very similar to what is actually found in Oreobolus (cf. Fig. 34). The perianth is modified variously (Figs. 21, 26, 30, 37, 39A, 42) in other genera. C, the racemose inflorescence with flowers lateral on the rachis. D, the sympodial inflorescence with flowers terminal on the rachis, a branch arising from the base of each flower (cf. 39B). E, the inflorescence as found in Uncinia and Carex in which the female branches are reduced to a single flower which is enclosed in the prophyll (utricle). F, a flower with both male and female organs functional but without perianth (cf. Cyperus, Pycreus, Mariscus). G, a female flower of Uncinia showing the hooked rachilla arising from below the flower. H, a female flower of Carex.
The illustrations (Figs. A-H) and explanations may be useful in understanding the structure of the inflorescence and flower and the nomenclature used in describing these features.page 30
The first key below is intended to distinguish the families most likely to be confused with the Cyperaceae while the second key, including both native and alien elements of Cyperaceae, is arranged in sub-families so that the grouping is as nearly as possible ‘natural’.
Key to the Related Families
|1||Fruit a dehiscent capsule||— 2|
|Fruit an indehiscent nut or caryopsis||— 4|
|Perianth present||— 3|
|3||Flowers unisexual; ovules solitary in each cell||Restionaceae|
|Flowers hermaphrodite: ovules numerous||Juncaceae|
|4||Stems hollow; styles more or less lateral, usually 2 per ovule, stigmas plumose||Gramineae|
|Stems solid; styles terminal, compound, stigmas not plumose||Cyperaceae|
Key to the Genera of Cyperaceae
|1||Nut enclosed in a utricle; flowers all unisexual (Caricoideae)||— 18|
|Nut not so enclosed; at least some flowers hermaphrodite||— 2|
|2||Spikelets not sympodial, the flower being between the axis and the glume; spikelets usually with numerous flowers||— 3|
|Spikelets sympodial, the axis being between the flower and its subtending glume, latter enclosing the flower at its base; flowers 1-3 per spikelet with several empty glumes below (Rhynchosporoideae)||— 12|
|3||Glumes distichous, the spikelets flattened (Cyperoideae)||— 4|
|Glumes spirally arranged, spikelets terete (Scirpoideae)||— 7|
|4||Styles 2-fid, nut lenticular, edge-on to rachilla (Figs. 6-7)||— 5|
|Styles 3-fid, nut trigonous, one face against rachilla (Fig. 9)||— 6|
|5||Heads capitate, branches very short (Figs. 1-4)||Kyllinga|
|Heads umbellate (Figs. 5-8)||Pycreus|
Fig. 1, Kyllinga inflorescence X 2-½. Fig. 2, Kyllinga spikelet X5. Fig. 3, Kyllinga nut X 10. Fig. 4. Kyllinga floral diagram. Fig. 5, generalised inflorescence of Pycreus, Cyperus and Mariscus. Fig. 6, Pycreus floral diagram. Fig. 7, Pycreus part of spikelet. Fig. 8, Pycreus nut of P. sanguionolentus X20. Fig. 9, floral diagram of Cyperus and Mariscus. Fig. 10, Cyperus part of spikelet. Fig. 11, Cyperus nut of C. tenellus X20. Fig. 12, Mariscus part of spikelet. Fig. 13, Mariscus part of inflorescence showing deciduous nature of rachilla. Fig. 14, Mariscus nut of M. ustulatus X20. Fig. 15, Carex generalised inflorescence of subgenus Eucarex. Fig. 16, Carex inflorescence of subgenus Vignaea. Fig. 17, Carex inflorescence of subgenus Primocarex. Fig. 18, Carex utricle. Fig. 19, Uncinia inflorescence. Fig. 20, Uncinia utricle.
Where no magnification is given, the illustrations are diagrammatic and not drawn to scale.
|6||Rachilla persistent, spikelets sessile or stalked, nuts of ovate order (in N.Z.), (Figs. 5, 9-11)||Cyperus|
|Rachilla deciduous above two lowest glumes which are empty, spikelets sessile or rachis, nuts of linear-lanceolate order (in N.Z.), (Figs. 5, 12-14)||Mariscus|
|7||Inflorescence ebracteate, solitary, terminal; nut crowned by an enlarged, glabrous, persistent stylebase (Figs. 21-22)||Eleocharis|
|Inflorescence bracteate or apparently lateral, spikelets usually 2 or more; nut otherwise||— 8|
|8||Style with long deflexed hairs at base (Figs. 23-24)||Fimbristylis|
|Style without such hairs||— 9|
|9||Perianth of long retrorsely-barbed bristles||— 10|
|Perianth lacking||— 11|
|10||Leaves present and exceeding the culms; inflorescence with several leaf-like bracts; nut deciduous from the perianth (Figs. 25-26)||Scirpus|
|Leaves absent or reduced to sheaths at the base of the culms, bract solitary and apparently continuing the stem; perianth persistent on the nut and falling with it (Figs. 29-30)||Schoenoplectus|
|11||Spikelets spirally arranged on the stem (Figs. 27-28)||Desmoschoenus|
|Spikelets clustered or umbelled (Figs. 33-35)||Isolepis|
|12||Perianth of six regular broad unthickened scales; ripe fruit terminal on culm (Figs. 33-35)||Oreobolus|
|Perianth of bristles, plumes, thickened scales or absent||— 13|
|13||Perianth plumose (Figs. 36-37)||Carpha|
|Perianth other or absent||— 14|
|14||Rachilla flexuous, elongated between the flowers, glumes deciduous (Figs. 38-40)||Schoenus|
|Rachilla not flexuous or elongated between the flowers, glumes persistent||15|
|15||Flowers with perianth of short thickened scales (terminating in attenuate, barbed bristles in L. laterale), (Figs. 41-42)||Lepidosperma|
|Perianth absent||— 16|
|16||Nut with tapering fimbriate style-base (Figs. 48-49)||Vincentia|
|Nut with swollen style-base, not fimbriate||— 17|
|17||Upper flower fertile; nuts angled or variously sculptured; style-base evident as hairy ciliate or spongy process on ripe nut; leafless or leaves flattened laterally (Figs. 41, 43-44)||Cladium|
Fig. 21, Eleocharis inflorescence X1. Fig. 22, Eleocharis nut with perianth X10. Fig. 23, Fimbristylis inflorescence X1. Fig. 24, Fimbristylis nut showing hairs on style-base X20. Fig. 25, Scirpus inflorescence X½. Fig. 26, Scirpus nut with perianth detached X10. Fig. 27, Desmoschoenus inflorescence X½. Fig. 28, Desmoschoenus nut X10. Fig. 29, Schoenoplectus inflorescence X½. Fig. 30, Schoenoplectus nut with persistent perianth X10. Fig. 31, Isolepis inflorescence X2-½. Fig. 32, Isolepis nut X20.
|Lowest flower fertile; nuts not conspicuously angled or sculptured; style-base not evident on ripe nut; leafy with broad laminae (Figs. 45-47)||Gahnia|
|18||Rachilla produced into a hook, spikes simple (Figs. 19-20)||Uncinia|
|Rachilla not produced into a hook, spikes simple or compound (Figs. 15-18)||Carex|
Notes to the Genera
The following explanatory notes are intended as a guide to those wishing to proceed to the species level. Most points of variance with Cheeseman's Manual (1925) are nomenclatural, i.e. the species are transferred to a different genus, and descriptions of them will be found under their former genus. Most introduced species are given except in Carex which will be found in Allan's Handbook of the Naturalised Flora of New Zealand, Government Printer, 1940.
- Kyllinga: a single introduced species, K. brevifolia Rottb.
- Pycreus: two species of comparatively recent notice, P. sanguinolentus (Vahl) Nees and P. polystachus (Rottb.) Beauv., both known only from North Auckland so far.
- Cyperus: three introduced species are common as weeds; some species are also grown as ornamentals.
- Mariscus: one native species, M. ustulatus (A. Rich.) C. B. Clarke in Cheeseman; a small introduced species, M. congestus (Vahl) C. B. Clarke, also occurs as a weed.
- Eleocharis: five species occur as natives.
- Fimbristylis: F. squarrosa Vahl is the only species in New Zealand.
- Scirpus: as here defined, this genus is confined to the three species recently described by V. J. Cook (1947) as S. caldwellii, S. medianus and S. perviridis, all of which had previously been included under S. maritimus Linn.
- Schoenoplectus: this includes the two native species previously known as Scirpus lacustris Linn, and Scirpus americanus Pers.
- Desmoschoenus spiralis (A. Rich.) Hook. f. is the only species of the genus and is confined to New Zealand.
- Isolepis: includes all the species in Cheeseman's Manual in the Section Isolepis of Scirpus.
Fig. 33, Oreobolus inflorescence X10. Fig. 34, Oreobolus in fruit showing perianth after glumes have fallen X10. Fig. 35, Oreobolus nut of O. pectinatus X20. Fig. 36, Carpha inflorescence X1. Fig. 37, Carpha nut with plumose perianth x2-½. Fig. 38. Schoenus inflorescence X1. Fig. 39, Schoenus: A, old spikelet showing flexuous rachilla; B, sterile glumes removed to show elongated rachilla carrying glume above subtended flower. Fig. 40, Schoenus nut of S. pauciflorus X20. Fig. 41, Lepidosperma and Cladium inflorescence X½. Fig. 42, Lepidosperma nut of L. laterale showing perianth X10.
- Oreobolus: three closely-related native species.
- Carpha alpina R.Br. is the only native species, which extends to Australia and New Guinea.
- Schoenus: a genus of nine well-marked native species; its position in the Rhynchosporoideae is somewhat anomalous with regard to the subdistichous glumes and often numerous fertile flowers. On other characters, however, it is obviously related.
- Lepidosperma: besides the two species given in the Manual, this includes Lep. australe (A. Rich.) Hook. f., the Cladium Vauthiera C. B. Clarke of Cheeseman's Manual.
- Vincentia: V. sinclairii (Hook. f.) Hamlin comb. nov.; Cladium sinclairii Hook. f. Handb. N.Z. Flora (1864) 305; V. anceps Hook. f. Fl. Nov. Zel. i (1853) 276 non (Poir.) Kunth. The only species in New Zealand.
- Cladium: this genus of nine New Zealand species is related very closely to Lepidosperma but differs, in New Zealand examples, in lacking a perianth and in having the lowest flower fruit-bearing.
- Gahnia: eight New Zealand species.
- Uncinia: a puzzling genus possibly reaching its greatest variety in this country. The species are much misunderstood and need extensive revision. Carex: one of the largest genera in the flora. There are three subgenera, mainly distinguished on characters of the inflorescence (Figs. 15-17).
- Attenuate — tapered.
- Bracteate — bearing bracts; here referring to the modified leaves subtending an inflorescence or part of an inflorescence.
- Capitate — globose, growing in a dense globular cluster.
- Ciliate — fringed with hairs.
- Culm — the stem including the inflorescence.
- Deciduous — falling off in season.
- Distichous — in two ranks on opposite sides of the axis.
- Ebracteate — without bracts.
- Fimbriate — fringed with broad flattened hairs or scales.
- Flexuous — zig zag, i.e. bent alternately in opposite directions.
- Glabrous — devoid of hairs.
- Glume — the bract subtending the flower.
Fig. 43, Cladium spikelet X5. Fig. 44, Cladium nut of C. tenax X20. Fig. 45, Gahnia lower third of inflorescence X½. Fig. 46, Gahnia spikelet of G. pauciflora X5. Fig. 47, Gahnia nut of G. pauciflora with nut split to show internal grooving X5. Fig. 48, Vincentia spikelet X5. Fig. 49, Vincentia nut showing fimbriate style-base X20.
- Lamina — the expanded portion of a leaf.
- Lenticular — lens-shaped, i.e. convex on both faces.
- Linear-Lanceolate — used here to indicate the condition where the length is greater than the breadth with the margins more or less parallel.
- Ovate — where the length is not much greater than the breadth with the sides more or less convex to each other.
- Perianth — the whorl of bracts surrounding the stamens, recognised from the latter by being barbed when filiform.
- Persistent — not falling in season, remaining after seed-fall.
- Prophyll — the sleeve-like or flask-shaped organ surrounding the base of a fertile branch.
- Rachilla — the ultimate branch which bears the flowers; in Caricoideae the spikelet is reduced to a single flower, hence the hook in Uncinia is a rachilla.
- Rachis — a primary branch of an inflorescence.
- Reflexed — bending downwards.
- Retrorse — pointing away from the apex.
- Sessile — without a stalk, sitting directly on the body from which it arises.
- Spike — an inflorescence bearing sessile flowers or spikelets.
- Spikelet — a cluster of one or more flowers on an ultimate branch of the inflorescence.
- Sympodial — of an inflorescence in which a branch arises at the base of a terminal flower.
- Trigonous — three-angled.
- Trimerous — the floral members in threes or multiples of three, e.g. 6 perianth segments, 6 stamens, 3 carpels.
- Umbellate — with the branches arising from a common point.
- Utricle — the flask-shaped organ surrounding the female flower in Uncinia and Carex.
Bentham, G., and Hooker, J. D., 1883 — Genera Plantarum Vol. III, London.
Cheeseman, T. F., 1925 — Manual of the New Zealand Flora, Govt. Printer, Wellington.
Clarke, C. B., 1909 — Illustrations of the Cyperaceae; Williams and Norgate, London.
Cook, V. J., 1947 — Descriptions of New Species of Scirpus; Trans. Roy. Soc. N.Z. Vol. 76: 4, pp. 567-571.
Kukenthal, G., 1909 — Cyperaceae-Caricoideae; Engler's Pflanzenreich, Heft 38, Leipzig. (A monograph of the Caricoideae including New Zealand Uncinia and Carex).
Vorarbeiten zu einer Monographie der Rhynchosporoideae; Repertorium specierum novarum regni vegetabilis, Leipzig, Vol. 44 (1938) Schoenus; 47 (1939) Carpha; 48 (1940) Oreobolus; 50 (1941) Lepidosperma.