The Most Australian of Plants

Imagine yourself standing in a remote corner of northern Australia. Before you stretches an expanse of rolling hills, extending as far as the eye can see. The hills are covered with a carpet of green. You step forward, eager to explore these open fields. But as you approach them, everything changes. What appeared to be a uniform carpet is actually dense tussocks, each separated by an underlay of bare gravel. And instead of soft, yielding blades, the tussocks offer you nothing but resin and hate. Welcome to spinifex country.

Grassland dominated by Triodia pungens (bright green) and T. basedowii (grey-green), copyright Hesperian.

The spinifexes of the genus Triodia are a uniquely Australian group of plants. Some North American grasses have been assigned to this genus in the past but have since been moved elsewhere. There is also a widespread genus of coastal grasses that formally goes by the name of Spinifex but that is something different again. In many parts of arid Australia (and arid Australia equals most of Australia), spinifexes are the dominant form of plant life. As noted above, they grow in tight tussocks that may reach remarkable sizes and densities: clumps of the largest species may reach 2.5 metres in height and six metres in diameter (Lazarides 1997). Not uncommonly, these largest patches will be ring-shaped due to the centre dying off while growth continues around the edges. The leaf blades are long, needle-shaped, woody and rigid. Speaking from experience, the sharp tips of these blades will break off all too easily, embedding themselves in the flesh of any passers by. And some idea of their rigidity will also be conveyed by the fact that, in the growth season, it was not uncommon to discover macabre shish kebabs made from jumping grasshoppers that had had the misfortune to land on the end of one.

Mature stand of Triodia irritans, showing the tendency of hummocks to grow into circles as the centre dies off. Copyright ANBG photo M. Fagg.

Nearly 70 species are currently recognised within the genus, often differing in their preferred microhabitat. One of the most common species, Triodia basedowii, extends its range across almost the entirety of the continent between 18 and 30 degrees South and west of the Great Dividing Range. This species has a preference for sandplains and dunefields. Other species are far more localised. Barrett & Barrett (2011) described two new species found in association with sandstone cliff faces in the Ragged Range in Western Australia. Triodia barbata was found only in a thin band along the top of the cliff faces and may have had a population of only about 300 individuals. The more abundant (but still not widespread) T. cremnophila was found only on the vertical faces of the cliffs themselves. However, it must be noted that large gaps may exist in our knowledge of the ranges of Triodia species because of the remoteness and difficulty of getting to many of the regions in which they are found (seriously, if you've never been to central Australia yourself, it is difficult to appreciate just how much Absolutely Nothing there is there). Triodia mollis is known from two widely separated regions in northern Western Australia and Queensland with no confirmed records as yet from the entire expanse of the Northern Territory in between.

Preferred habitat of Triodia cremnophila, from Barrett & Barrett (2011). Yes, it only grows on the cliff face. Yes, someone presumably went down the cliff face to get specimens.

Being as woody and harsh as it is, it should come as no surprise that relatively few animals are capable of eating spinifex. Many Australian termites, such as the endemic genus Drepanotermes, are spinifex specialists; workers of Drepanotermes may be seen leaving their nest at night to collect pieces of spinifex blades and carry them back. Pastoralists may refer to 'hard' and 'soft' spinifex varieties but the difference is one of degree only; even the 'soft' spinifexes (usually the resin-producing species) are pretty damn hard by the standards of any other grass. Livestock are sometimes grazed on spinifex when bettter options are unavailable, in which case patches of spinifex may be burnt off to encourage the production of younger, more palatable growth (spinifex burns exceedingly well but also grows back readily from the remnant rootstock). The resin from spinifex also has a history of being used by indigenous Australians as an adhesive when making tools. For the most part, though, the main value of spinifex remains in its role as the dominant vegetation and habitat for the areas where it is found.

REFERENCES

Barrett, R. L., & M. D. Barrett. 2011. Two new species of Triodia (Poaceae: Triodieae) from the Kimberley region of Western Australia. Telopea 13 (1–2): 57–67.

Lazarides, M. 1997. A revision of Triodia including Plectrachne (Poaceae, Eragrostideae, Triodiinae). Australian Systematic Botany 10: 381–489.

The Resurrection of Grass

The resurrection grass Oropetium thomaeum, photographed by Diana Margaret Napper.
Even for a grass, the annual Oropetium thomaeum is not a very prepossessing plant. Only a couple of inches in height, it can be found as small tufts in arid or saline habitats in tropical Africa and Asia. In some parts of India, it has been recorded as a dominant grass species, probably because its small size makes it resistant to grazing while, for instance, its somewhat taller perennial relative O. roxburghianum is restricted to growing under shrubs that protect it from hungry ruminants (Gaff & Bole 1986).

Despite its modesty, O. thomaeum is not devoid of interest. It is an example of what is known as a 'resurrection plant', able to survive severe desiccation in a dormant state only to apparently come back to life after rain. Because O. thomaeum is a diploid species with a relatively small genome (one of the smallest of all grasses), it has been touted as potential useful in studying the genetic factors controlling drought tolerance (Bartels & Mattar 2002). According to this article, it has seen some use in attempts to rehabilitate degraded environments. Oropetium thomaeum has also been shown to differ from most plant species in that it is the shoot that emerges first from the germinating seed rather than the root (Dakshini & Tandon 1970).

Oropetium is a small genus of seven species of grasses in the subfamily Chloridoideae, with three species found in India and five in Africa (Phillips 1975). Despite the small number of species, members of Oropetium have been divided between no less than five genera in the past, reflecting a fair degree of disparity in their reproductive morphology. All, however, are relatively small narrow-leaved grasses forming dense tufts. Whether the African species possess the resurrective abilities of the Asian species remains, so far, unknown.

REFERENCES

Bartels, D., & M. Z. M. Mattar. 2002. Oropetium thomaeum: a resurrection grass with a diploid genome. Maydica 47 (3-4): 185-192.

Dakshini, K. M. M., & R. K. Tandon. 1970. An unusual type of germination of graminaceous seed. Annals of Botany 34 (2): 423-425.

Gaff, D. F., & P. V. Bole. 1986. Resurrection grasses in India. Oecologia 71: 159-160.

Phillips, S. M. 1975. A review of the genus Oropetium (Gramineae). Kew Bulletin 30 (3): 467-470.

From Giant Reeds to Tiny Leaves

Giant reed Arundo donax, photographed by Russ Kleinman & Richard Felger.

The grasses are without a doubt one of the most successful groups of plants in the modern environment. So it is only fitting that for today's post I'm going to be looking at one of the subgroups of the grasses, the Arundinoideae.

The Arundinoideae, including the reeds and related species, has been long recognised as a subfamily of grasses, but rather vaguely so. Most of the characters of leaf anatomy previously used to define the group are either plesiomorphies or absences. Arundinoids use the plesiomorphic C₃ photosynthetic pathway rather than the derived C₄ pathway and lack the radiate leaf anatomy associated with C₄ photosynthesis. They also lack the fusoid leaf cells with accessory arm cells that are characteristic of the bamboos. In other features, 'arundinoids' were quite variable, and it therefore came as no surprise to anyone when phylogenetic analyses indicated that the group was polyphyletic. As a result, the Grass Phylogeny Working Group (2001) divided the arundinoids between a number of subfamilies, separating the wiregrasses as the Aristidoideae and the oatgrasses and pampas grasses as the Danthonioideae. This reduced the Arundinoideae proper, previously including well over 600 species, to less than 40.

Common reed Phragmites australis, from here.

Even so, the arundinoids remain a disparate group, and morphological synapomorphies of the group remain elusive. The taxonomic core of the group, the reeds of the genera Arundo, Phragmites and Molinia, are connected by the possession of hollow culm internodes, a punctiform hilum (the detachment scar on the 'seed') and convex adaxial rib sides in the leaf blade (Grass Phylogeny Working Group 2001), but these features are not shared by all other arundinoids. The reeds are found in damp habitats, and the common reed Phragmites australis can grow in standing water. The largest species, the giant reed Arundo donax, can reach a height of ten metres under ideal growth conditions. In contrast, the Tom Thumb grass Dregeochloa pumila is found in the Namib Desert of South Africa and Namibia, and doesn't reach any higher than 25 mm (excluding the flower stalk, which may give it another inch or so). Dregechloa pumila is also remarkable as the only succulent species of grass. Also included in the Arundinoideae are the crinipoid grasses, a somewhat poorly known assemblage of species found in highlands of Africa, Madagascar and southern India (Linder et al. 1997).

Tom Thumb grass Dregechloa pumila, from Ernst van Jaarsveld.

Arundo donax has become known in some areas as an agressive weed, particularly in the US. It has one of the fastest growth rates of any plant, potentially up to ten centimetres in a single day (remember, that's four Dregeochloas!) Despite its invasive potential, some have been promoting it as a potential crop species, particularly for the biofuel market (presenting its fast growth rate as an outright advantage). Arundo donax is also the preferred material for woodwind reeds. Phragmites australis (also a problematic weed in the wrong circumstances) has been used in wastewater purification, and Wikipedia also notes that it is edible, quoting that the young stems "while still green and fleshy, can be dried and pounded into a fine powder, which when moistened is roasted like marshmallows". 'Like' marshmallows, perhaps, but I don't think that I'll be rushing to make the substitution.

REFERENCES

Grass Phylogeny Working Group. 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Annals of the Missouri Botanical Garden 88 (3): 373-457.

Linder, H. P., G. A. Verboom & N. P. Barker. 1997. Phylogeny and evolution in the Crinipes group of grasses (Arundinoideae: Poaceae). Kew Bulletin 52 (1): 91-110.

Stacks of Barley (Taxon of the Week: Hordeum)

Foxtail barley, Hordeum jubatum, a weedy species found in northern North America and northeast Asia. Photo by Colin Stone.

Hordeum is a genus of thirty or so species (Blattner, 2009, lists 33) whose native range mostly covers Eurasia and the Americas though various species have been spread by humans pretty much throughout the world, either willingly or unwillingly. The most significant of these species from a human perspective is Hordeum vulgare, barley, used in the making of refreshing beverages and the manufacture of eyewear. This is the genus that gave us beer.


Six-rowed barley, Hordeum vulgare, the main cultivated variety of barley. Hordeum species bear single-flowered spikes in groups of three but usually only the central spike develops a seed while the lateral two are abortive. Six-rowed barley has been bred so all three develop seeds. Photo from here.

Hordeum is one of the more basally diverging genera in the grass tribe Triticeae, previously discussed here in relation to the genus Elymus. Unlike many other triticean genera, the concept of Hordeum has remained relatively stable with the exception that some authors have restricted Hordeum to the species H. vulgare and H. bulbosum, placing the other species in a genus Critesion. Blattner (2009) divided the genus into five sections, four monophyletic (sensu Ashlock, at least) sections corresponding to the four genome types found in Hordeum (see the Elymus post for an explanation of the concept of genome types) and an explicitly polyphyletic section Nodosa for species derived from hybrids between species of sections Marina and Stenostachys.


Hare barley, Hordeum murinum ssp. leporinum, native to Europe but widely established around the world. Photo from here.

Hordeum is most diverse in the Americas - 24 species are found naturally in the New World (including two, H. brachyantherum and H. jubatum, that are also native to northeast Asia) with 15 of those native to South America. However, phylogenetic studies show that the genus is in fact Eurasian in origin with all of the New World diploid species belonging to a subclade of a single section (Stenostachys) which probably arrived in North America about four to six million years ago (Blattner, 2009). A number of the polyploid New World species (including both the Bering Strait-straddling species) appear to be derived from hybrids between New World Stenostachys and one of the central Asian Stenostachys species, probably H. roshevitzii - my guess is that they form a tribute to the ability of pollen to be carried amazingly long distances. Also biogeographically interesting are the section Nodosa species, the European H. secalinum and the South African H. capense. Hordeum secalinum appears derived from a cross between the mostly Mediterranean section Marina and a Stenostachys species (the ranges of the two sections overlap in central Asia). Hordeum capense is a biogeographical enigma; geographically isolated from all other species, it carries the same genome combination as H. secalinum (Baum & Johnson, 2003; Blattner, 2009) with which it is morphologically almost identical. Indeed, for a long time H. capense was regarded as a human-introduced population of H. secalinum, probably brought over in the earliest days of European colonisation. However, hybrids between H. secalinum and H. capense are infertile (Baum & Johnson, 2003). Petersen & Seberg (2004) calculated that the genetic divergence between H. secalinum and H. capense was too great for it to be a recent derivative of a human introduction; instead, they felt it must be an older relict that had reached South Africa by means unknown.

REFERENCES

Baum, B. R., & D. A. Johnson. 2003. The South African Hordeum capense is more closely related to some American Hordeum species than to the European Hordeum secalinum: a perspective based on the 5S DNA units (Triticeae: Poaceae). Canadian Journal of Botany 81: 1-11.

Blattner, F. R. 2009. Progress in phylogenetic analysis and a new infrageneric classification of the barley genus Hordeum (Poaceae: Triticeae). Breeding Science 59: 471-480.

Petersen, G., & O. Seberg. 2004. On the origin of the tetraploid species Hordeum capense and H. secalinum (Poaceae). Systematic Botany 29 (4): 862-873.

Scattering the Sheaves (Taxon of the Week: Elymus)

Canada wildrye, Elymus canadensis, a widespread species in North America. Photo by Russ Kleinman & Bill Norris.

Elymus is a cosmopolitan genus of perennial tufted and/or rhizomatous grasses that, depending on the taxonomic treatment used, may include from 20 to 200 species found mostly in cool temperate parts of the world (Quattrocchi, 2006). Bit of a difference between those extremes, you may be thinking? Elymus is part of the Triticeae, the grass tribe that includes wheat, rye and barley. Establishing relationships within the Triticeae has always been a difficult prospect; hybridisation and polyploidy have been major factors in the evolution of the tribe. Until the mid-1980s, most western authors continued to use a classification whose basic philosophy went right back to Linnaeus' Species Plantarum (Barkworth, 2000). This system, in which Elymus contained perennial grasses with 2 or more 2- to 6-flowered spikelets at each node of the rachis (the flower spike), was unashamedly pragmatist and concerned with facilitating species identification rather than describing relationships. A more modern classification had been proposed by a Russian author, Nevski, in the early 1930s but had not been widely accepted outside the communist countries. Among Nevski's most significant changes was the realisation that reduction in the number of flowers at each spikelet to one had occurred multiple times in various genera and his Elymus included species with from one to six flowers.

Starting in the 1940s, an increasing number of cytogenetic studies had established that many of the genera of Triticeae contained chromosomally disparate subgroups that could be identified by the chromosome pairing patterns in hybrids between taxa. A number of authors had integrated some cytogenetic data into revisions of Triticeae but two authors in 1984 independently suggested that Triticeae classification should be based entirely on cytogenetic data alone. Not surprisingly, this lead to a botanical rift - even if one was willing to credit that genetic characters might be a better indication of relationships than morphology (and not everyone was), they were of limited use for field identifications. Before gene sequencing became widely feasible, identifying the cytogenetic nature of a grass required observation of cells undergoing meiotic division. However, genomic data remains a significant factor in Triticeae classification (Barkworth, 2000).


Bottlebrush grass, Elymus hystrix, an inhabitant of the northwest United States from West Virginia to New York. Photo from here.

Each of the genome groups that has been identified in Triticeae has been assigned a letter code: A, B, N, R, etc. Polyploid taxa of hybrid origin may carry chromosomes from more than one genome group; the genus Triticum (wheats), for instance, is characterised as AB (or some further complication thereof, such as AAB). The basic chromosome type of Elymus for North American representatives is StH, representing their descent from one or more hybridisation events between the genera Pseudoroegneria (St) and Hordeum (H; Hordeum includes the barleys) (Mason-Gamer, 2001). Taxa from other parts of the world currently assigned to Elymus all carry the St genome, but may have it combined with different genomes such as Y or W*. Future investigation is required to establish whether these taxa are appropriately placed in Elymus.

*As ploidy level increases, the genome codes for various taxa can get a little hideous. The North American octoploid genus Pascopyrum, for instance, has the genome code StStHHNsNsXX.

Economically speaking, a number of Elymus species are used as pasture grasses for feeding livestock. Quattrocchi (2006) indicates that Elymus grain is usable for food but I haven't found any references to specific species being regularly used as such (apart from indirectly with Elymus species being used in wheat outcrossing). Elymus repens, couch grass, is a particularly tough rhizomatous species that seems to be encouraged in some situations and regarded as a curse in others (many authors refer to couch grass as Elytrigia repens instead but it carries the genome StStH - Barkworth, 2000).

REFERENCES

Barkworth, M. E. 2000. Changing perceptions of the Triticeae. In Grasses: Systematics and Evolution (S. W. L. Jacobs & J. Everett, eds) pp. 110-120. CSIRO: Melbourne.

Mason-Gamer, R. J. 2001. Origin of North American Elymus (Poaceae: Triticeae) allotetraploids based on granule-bound starch synthase gene sequences. Systematic Botany 26 (4): 757-768.

Quattrocchi, U. 2007. CRC World Dictionary of Grasses: common names, scientific names, eponyms, synonyms, and etymology vol. 2. CRC Press.

Strangers from Parts Unknown (Taxa of the Week: Juncus section Juncotypus, Juncus amabilis)

Flowerhead of Juncus conglomeratus. If you look closely, you can see the line where the true stem ends, and the elongate stem-like flower bract begins. Photo from Nature Notes from Argyll.

Rushes of the genus Juncus are a large cosmopolitan assemblage of superficially grass-like plants, most commonly found in damp or swampy soils. A number of distinct subgroups are recognisable within the genus, and my subject today is one of those subgroups, the section Juncotypus in the subgenus Agathryon. Most older references will refer to this group as the subgenus or section Genuini, but the precendence of Juncotypus was noted by Kirschner et al. (1999)*. Both names, however, can be translated to give a good idea of what defines this group - section Juncotypus is the "genuine" rushes. Species of this species lack true leaves entirely (the leaves have been reduced to small sheaths at the base of the stem), and instead have clumps of umbranching photosynthetic stalks rising from a basal woody rhizome. The flower clusters appear to born laterally some way down the stalk (Healy & Edgar, 1980; though admittedly, calling the tiny wind-pollinated reproductive organs of rushes "flowers" arguably stretches the term to its limits), but are in fact not - rather, the part of the "stalk" extending past the inflorescence is really the flower bract.

*A few notes for my more zoologically-oriented readers. While zoological nomenclature allows only one formal division between species and genus, the subgenus, botanical nomenclature allows (from highest rank to lowest) subgenus, section, subsection, series and subseries. And while zoological taxonomists tend to be a little chary when it comes to using subgenera, botanical taxonomists have a long history of using every one of those subsidiary ranks to full capacity (some botanists have managed to pluck even further levels out of the ether). Also, while zoological taxonomy interpolates subgeneric names into the full species names (e.g. Brachiosaurus (Giraffatitan) brancai), botanical taxonomy does not - Juncus amabilis is a member of the section Juncotypus, but that doesn't mean that it should be called "Juncus (Juncotypus) amabilis". Finally, while zoological taxonomy regards subgeneric names as distinct entities at the same level of homonymy as generic names (Giraffatitan is nomenclaturally distinct from Brachiosaurus, and because the name has been used for a subgenus, it cannot be used for another genus or subgenus), botanical taxonomy regards the subgeneric name as directly connected to the generic name, so the proper name for today's subject is "Juncus section Juncotypus", not just "Juncotypus". One side-effect of this is that using a name for a subgeneric taxon in one genus does not prevent its use in association with another genus, so (e.g.) Crassula section Glomeratae and Campanula series Glomeratae are not regarded as homonyms.

If you're feeling horribly lost about now, take comfort in my assuring you that, yes, botanical nomenclature really is as horribly complicated as it looks. Personally, I don't understand a word of it.

Species of section Juncotypus are found in temperate habitats over most of the world. Some species are found in tropical latitudes, such as Juncus aemulans in Central America (Mexico to Guatemala) and Juncus decipiens in eastern Asia and New Guines, but at high altitudes (Snogerup et al., 2002; Wilson & Johnson, 2001). More than half the recognised species are found in Australasia, while a few species such as Juncus effusus are found over almost the entire range of the subgenus as either natives or adventives. Some members of the section are notable pasture pests. Though morphologically distinct, recent phylogenetic analyses have not supported the monophyly of the section Juncotypus (Drábková et al., 2006; Drábková & Vlček, 2009). Drábková & Kirschner (2004) particularly commented on the intermediate morphology of Juncus uruguensis between sections Juncotypus and Steirochloa. These results have not yet been incorporated into a taxonomic revision, probably because as yet only a relatively small number of Juncotypus species have been studied in this regard.


Juncus effusus. Photo from here..

Not surprisingly in light of their simple morphology, species of section Juncotypus have mostly been difficult to distinguish. In this regard, I can't do much better than steal wholesale the words of Edgar (1964):

Although the Junci Genuini show obvious differences of habit and colour in the field, these differentiating characters are largely lost in pressing and drying, and herbarium specimens are often difficult to determine. The principal characters which have been used to distinguish the plants are the general size, the presence or absence of lacunae in the pith of the stem, the varying compactness of the inflorescence, the number of stamens, and the relative size of the capsules. Yet none of these characters is wholly satisfactory. For instance, if the general size of the plant is used as a diagnostic character there is an obvious difficulty in placing intermediate sizes. Then, the appearance of the pith in longitudinal section, i.e., whether continuous or interrupted by air spaces, is a very useful feature, but is not constant within some of the species nor, on occasion, even within one plant. Only three species in New Zealand invariably have six stamens and all the others have normally three, though four, five, or even six stamens may be found in occasional flowers. Again, the structure of the inflorescence is constant in some species but extremely variable in others, the flowers are small and inconspicuous and the tepals lose most of their character on drying. Lastly, the ratio between capsule-length and tepal-length which can be a very useful diagnostic character in other groups of Juncus is more difficult to use in this subgenus. In the species with larger capsules it is quite reliable, but in the species with the smallest flowers the difference in length between capsule and tepals is rarely greater than 0.5 mm and usually very much less, so that the ratio between the lengths does not make a convenient diagnostic character.

Diagnostic features of Juncus amabilis. Images from here.

When she made this complaint, Edgar (1964) was reviewing the New Zealand species of "Juncus genuini". In that paper, she described a new species Juncus amabilis, which was distinguished by its small size, extremely dark red-purple basal sheaths and pointed capsules that were distinctly longer than the tepals. Juncus amabilis has a distinctly scattered distribution in New Zealand, with specimens recorded from Auckland, Waikato, the Bay of Plenty, southern Canterbury and Otago (for those unfamiliar with New Zealand geography, that leaves a big gap across the southern North Island and northern South Island without records).

It wasn't until later that the reason for this unusual distribution pattern became clear, when Juncus amabilis was also identified in damp wastelands (primarily along river edges) in southern Australia. It now appears likely that, in spite of where it was initially discovered, J. amabilis is not a native of New Zealand, but an introduction from Australia*. Within Australia, the distribution of J. amabilis remains scattered (a map can be seen here) but, while uncommon, the species does not seem to be regarded as particularly endangered. It looks as if habitat availability rather than human impact may be the cause of its rarity.

*This is unusual, but not unique. A number of organisms have been described as introductions before being recorded from their native ranges. Among harvestmen, for instance, the species Ibantila cubana was originally described (as the species name indicates) from Cuba. However, I. cubana is the only species of the Old World family Podoctidae recorded from the Americas and was collected in a botanical garden, so it is almost certainly an exotic (Kury, 2003). The original homeland of this species remains as yet unknown.

REFERENCES

Drábková, L., J. Kirschner & Č. Vlček. 2006. Phylogenetic relationships within Luzula DC. and Juncus L. (Juncaceae): a comparison of phylogenetic signals of trnL-trnF intergenic spacer, trnL intron and rbcL plastome sequence data. Cladistics 22 (2): 132-143.

Drábková, L., & J. Kirschner. 2004. Juncus uruguensis - a member of the section Juncotypus (Juncaceae, Juncus subg. Agathryon). Nordic Journal of Botany 22: 687-691.

Drábková, L. Z., & Č. Vlček. 2009. DNA variation within Juncaceae: comparison of impact of organelle regions on phylogeny. Plant Systematics and Evolution 278: 169-186.

Edgar, E. 1964. The leafless species of Juncus in New Zealand. New Zealand Journal of Botany 2: 177-204.

Healy, A. J., & E. Edgar. 1980. Flora of New Zealand vol. III. Adventive cyperaceous, petalous and spathaceous monocotyledons. P. D. Hasselberg, Government Printer: Wellington (New Zealand).

Kirschner, J., L. J. Novara, V. S. Novikov, S. Snogerup & Z. Kaplan. 1999. Supraspecific division of the genus Juncus (Juncaceae). Folia Geobotanica 34 (3): 377-390.

Kury, A. B. 2003. Annotated catalogue of the Laniatores of the New World (Arachnida, Opiliones). Revista Ibérica de Aracnología, special monographic volume 1: 1-337.

Snogerup, S., P. F. Zika & J. Kirschner. 2002. Taxonomic and nomenclatural notes on Juncus. Preslia 74: 247-266.

Wilson, K. L., & L. A. S. Johnson. 2001. The genus Juncus (Juncaceae) in Malesia and allied septate-leaved species in adjoining regions. Telopea 9 (2): 357-397.