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, AgResearchLeaves are hollow
Larry Allain, USGS, Wetland & Aquatic Research Center / Trevor James, AgResearchStem has cross walls below flower heads
Trevor James, AgResearchFlower heads have fewer than 30 flowers, and leaves are not bristly
Kerry Bodmin, NIWA / Trevor James, AgResearchStem does not have cross walls below flower heads
Kerry Bodmin, NIWA / Trevor James, AgResearchPlant has more than 5 flower heads
Trevor James, AgResearchCapsule tapers to its tip
Trevor James, AgResearchLeaves originate at the plant's base (are basal), and are often broad with a grass-like appearance
Trevor James, AgResearch / Kerry Bodmin, NIWACapsule is 2.5-3 mm long
Trevor James, AgResearch / Kerry Bodmin, NIWALeaves are not flat, usually with a single flower head; flower stalks rarely start from a central point
Trevor James, AgResearch / Ros Cole, Department of ConservationTepals are 3 mm long or less
Kerry Bodmin, NIWATepals are longer than 3 mm
Trevor James, AgResearchLeaves are tall and round, like flowering stems
Trevor James, AgResearchLeaves are reduced to basal sheaths, and only flowering stems are tall
Trevor James, AgResearchPith in stems is continuous
Trevor James, AgResearchFlower head has a single dense cluster or, rarely, two clusters
Trevor James, AgResearch / Kerry Bodmin, NIWAFlower heads are open, with more than one cluster
Trevor James, AgResearchStems are clearly ridged
Tasmanian Herbarium, Threatened Species Section, Department of Primary Industries, Parks, Water and Environment, Tasmania / Trevor James, AgResearchStems are soft, green to yellow-green in colour, and 2 mm or less in diameter
Trevor James, AgResearch / Allan Herbarium, Landcare ResearchFlowers are loosely clustered or solitary
