Bromus arenarius
Common names
sand brome
Biostatus
Native
Category
Vascular
Structural class
Grasses
Detailed description
Yellow-green annual 200–860 mm tall, tufted or solitary, basal leaves withering at or before flowering. Leaf-sheath densely villous. Ligule 1–2.6 mm, lacerate. Leaf-blade 70–300 × 1.7–5 mm, densely villous. Culm 150–600(–800) mm, erect or geniculate-ascending, internodes pubescent below panicle. Panicle 70–260 mm, lax, nodding; branches filiform, curving. Spikelets 30–40 mm, 5–8-flowered, numerous, loosely hairy, oblong-lanceolate to wedge-shaped. Glumes unequal, acute, acuminate, apery, covered within long fine hairs; lower 7–9.5 mm, 3-nerved, narrow oblong-lancelate, upper 9.5–13 mm, 5–7-nerved, narrow elliptic-lanceolate. Lemma 11–14 mm, 7–9-nerved, rounded, papery, oblong- to narrowly elliptic-lanceolate, covered with long fine hairs, apex sometimes entire or with 2-acute lobes, awn 14–20 mm, arising 2 mm below lemma apex. Palea ¾ length of lemma, keels sparsely long-ciliate, interkeel glabrous. Callus with minute hairs. Rachilla 1.2 mm, pubescent. Anthers 0.8–1.5 mm.
Similar taxa
A distinctive late winter to spring time annual, which has usually dried off by December. It can be distinguished from all other bromes naturalised in New Zealand by the 3-nerved lower glume, and 5–7-nerved upper glume, loosely hairy spikelets, and by the glabrous interkeels of the palea.
Distribution
Indigenous. In New Zealand known from mainly coastal locations from the Three Kings Islands south to Mahia Peninsula, thence disjunct to Wellington Harbour, and the Chatham Islands. It has been found once in the South Island, inland at Molesworth in Marlborough. Also on Norfolk Island and along the eastern side of Australia.
Habitat
Coastal to lowland (with one montane record from Marlborough). A species of open rocky ground. coastal cliff faces, scree and boulderfield. Often associated with sea bird nesting grounds, especially gulls.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | At Risk – Naturally Uncommon | Qualifiers: Sp, DPR, DPS, DPT, EF, PF, TO
Threats
Although not really threatened this species is never particularly common anywhere. It has a naturally sporadic distribution.
Detailed taxonomy
Family
Synonyms
None in New Zealand
Taxonomic notes
Although Edgar & Connor (2000, Flora of New Zealand Vol. V) regard this species as an early European introduction, the reason for this decision was not given (though one assumes this is because early collections were made from the vicinity of ports), but as its seeds are bird dispersed, and its ecology and distribution shows strong links to sea bird nesting grounds, it is just as likely that it is indigenous here. Prior to the publication of Flora V, B. arenarius had always been regarded as indigenous. Despite the decision made by Edgar & Connor (2000) NZPCN see no reason to regard this species as any thing other than indigenous.
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
(July–)August–October
Fruiting
August–December
Propagation technique
An annual. Easily grown from fresh seed. Rather attractive when flowering.
Other information
Etymology
bromus: From the ancient Greek word bromos, referring to a kind of oat
arenarius: Sand dweller
Manaaki Whenua Online Interactive Key
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
BROARE
Chromosome number
2n = 28
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | At Risk – Naturally Uncommon | Qualifiers: EF, Sp, TO
2012 | At Risk – Naturally Uncommon | Qualifiers: EF, SO, Sp
2009 | At Risk – Naturally Uncommon | Qualifiers: EF, SO
2004 | Sparse
Regional conservation statuses
Auckland: 2025 | Threatened – Regionally Endangered | Qualifiers: DPR, DPS, DPT, EF, NStr, PF, RR, TO
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Auckland conservation status information is sourced from the “Conservation status of vascular plant species in Tāmaki Makaurau / Auckland” Simpkins E et al. (2025) report.
Referencing and citations
References and further reading
Edgar E, Connor HE. 2000. Flora of New Zealand. Vol. V. Grasses. Christchurch, Manaaki Whenua Press. 650 p.
Attribution
Description modified from Edgar and Connor (2000)
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.