Rushes (family Juncaceae) are a common component of New Zealand wetland vegetation and species within this family appear very similar.
With over 50 species, Juncus are the largest component of the New Zealand rushes and are notoriously difficult for amateurs and professionals alike to identify to species level.
This field identification guide and accompanying factsheets have been developed to enable users with a diverse range of botanical expertise to identify Juncus to species level. The best time for collection, survey or identification is usually from December to April as mature fruiting material is required to distinguish between species. Factsheets (hyperlinked and available below) developed for each species provide more detailed information on descriptions for both native and exotic species, distribution within New Zealand, habitat, similar species and photographs of key features.
Using this guide
In preparing this field identification guide and factsheets we have used everyday language and have kept botanical terms to a minimum. Any technical terms have an alternative, plain English, wording and are identified on accompanying photographs or images. Each step of this key involves two choices, each described and illustrated with image(s) of the characteristic in question. It is therefore important to have mature, fruiting material to use this key.
With your specimen in hand, start at the top left image in this gallery. On each following page, our interactive HTML key will give you two possible choices. The choices you make will end up in a species identification, and link to a PDF factsheet containing more detailed information.
Start identifying your Juncus sample using our HTML key
You can also download a PDF version of the key, as well as combined and individual fact sheets for all the Juncus species in the key.
Download the Juncus key as a single document [PDF 14MB]
Download Juncus species factsheets
Taxonomic treatment of Juncus in this key generally follows the family monograph by Kirschner (2002). Species features and descriptions were taken from Kirschner (2002), as well as the New Zealand Flora volume III (Healy & Edgar, 1972).
- Kirschner J (2002a) Juncaceae 2: Juncus subg. Juncus, Species Plantarum: Flora of the World Part 7 (336 p). Australian Biological Resources Study, Canberra.
- Kirschner J (2002b) Juncaceae 3: Juncus subg. Agathryon, Species Plantarum: Flora of the World Part 8 (192 p). Australian Biological Resources Study, Canberra.
Trevor James, AgReserach / Allan Herbarium, Landcare ResearchStems are smooth to the touch, or have more than 30 ridges
Trevor James, AgResearchPith is cobwebby
Allan Herbarium, Landcare Research / Kerry Bodmin, NIWALower branches point upwards
Trevor James, AgResearch / Allan Herbarium, Landcare Research / Auckland Museum HerbariumPith is not cobwebby, and stems are wiry
Trevor James, AgResearchPith in stems is interrupted or lacking
Trevor James, AgResearchPith is interrupted
Trevor James, AgResearchFlowers are grouped at the ends of branches
Trevor James, AgResearchFlower heads are open or have a cluster 10 mm or more in diameter
Trevor James, AgResearchStems are not bright green, and capsules are 2-3.5 mm long
Trevor James, AgResearchBasal sheaths are shiny and red or chestnut brown at their base
Kerry Bodmin, NIWA / Trevor James, AgResearchBasal sheaths are very dark red-purple to black or dull brown at their base
Trevor James, AgResearchFlower heads have a cluster 10 mm or less in diameter, often with smaller clusters above
Trevor James, AgResearchStems are less than 1.5 mm in diameter
Trevor James, AgResearchFlowers are evenly-distributed along branches
Trevor James, AgResearchBasal sheaths are dark purple, or red-purple to black
Trevor James, AgResearch / Allan Herbarium, Landcare Research / Forest and Kim StarrBasal sheaths are pale to dark brown, or pinkish to red-brown
Auckland Museum Herbarium / Trevor James, AgResearchStem ridges are distinct, and base sheaths are pink or red-brown in colour
Kerry Bodmin, NIWA / Bush Heritage Australia / Paul Champion, NIWAStem ridges are not distinct, and base sheaths are golden to dark straw brown
Trevor James, AgResearchLeaves originate at the base and up the stem, and are usually narrow and often wiry
Trevor James, AgResearchFlowers are evenly distributed on branches/branchlets
