Carmichaelia hollowayi
Common names
Holloway’s broom
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Trees & Shrubs - Dicotyledons
Simplified description
Rare low-growing shrub with many yellowish erect leafless orange-tipped branches inhabiting limestone in the Waitaki Valley. Branches 3.5mm wide, with rounded tip. Flowers small, pea-like, white with dark purple centre, in small clusters. Fruit a long-lasting sharp-tipped dry pod containing 1-3 hard olive seeds.
Flower colours
Violet/Purple, White
Detailed description
Dwarf, suckering broom, up to 0.5 x 1(-2) m. Branches 10-30 mm diam., stout, horizontal, spreading, cladodes virtually leafless, 50-80(-100) x 3.5 mm, erect to spreading, yellow-green, apex rounded, never sharp-tipped. Leaves when present, simple, 4.5-12.5 x 1.8-4.5 mm, obovate to oblanceolate, green. Inflorescence a (1-)2-3-flowered raceme, flowers dark purple. Standard 7-8 x 7-8 mm, broad-orbicular, erect, purple or red-purple, margins white. Wings 5.5-6.5 x 2.5-3 mm, oblong, white, purple veined, keel 5 x 3.5 mm, distally tinged purple otherwise white or purple-veined. Pods long persistent, 8-11 x 4.8-6 mm, broad elliptic, laterally compressed, valves very flat. Seeds 2.5-2.9 x 2.4-2.6 mm, reniform, 1(-2) per pod, yellow-green or green with black mottling.
Similar taxa
Carmichaelia hollowayi is identified by the pod, which is conspicuously laterally compressed and by the cladode apex which is rounded rather than sharp-tipped like Waitaki forms of C. petriei Kirk and C. australis R.Br. It is one of three native brooms (the others are C. astonii G.Simpson and C. glabrescens (Petrie) Heenan) naturally confined to limestone rock and associated soils.
Distribution
Endemic. South Island, where it is only known from limestone outcrops on the south bank of the Waitaki River.
Habitat
Limestone bluffs, outcrops, colluvium and their associated rendzina soils.
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.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- 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 | Threatened – Nationally Critical | Qualifiers: CD, DPT, RR, RF
Threats
There are less than 250 adult plants in the wild found in three populations. Because the species suckers, exact numbers of adult plants cannot be determined and it is likely than there are far fewer than currently believed. Although two of the three known populations occur on protected or covenanted land, the species remains at serious risk at all sites from browsing animals and from competition by tall grasses, shrubs and hawkweeds. Aside from these issues recruitment failure (in part linked to weed control) seems to be critical problem.
Detailed taxonomy
Family
Fabaceae
Synonyms
None
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
November - December
Fruiting
January - May
Life cycle and dispersal
Seeds are possibly dispersed by wind and granivory (Thorsen et al., 2009).
Propagation technique
Easily grown from fresh seed. Can also be grown by hardwood cuttings but these can be slow to take root. Plants will not tolerate humid conditions, and require a sunny, well drained, fertile soil.
Other information
Etymology
carmichaelia: After Carmichael, a botanist
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.
CARHOL
Chromosome number
2n = 32
Previous conservation statuses
2017 | Threatened – Nationally Critical | Qualifiers: CD, RR, RF
2012 | Threatened – Nationally Critical | Qualifiers: CD, RF, RR
2009 | Threatened – Nationally Critical | Qualifiers: CD, RF, RR
2004 | Threatened – Nationally Critical
Referencing and citations
References and further reading
de Lange, P.J.; Heenan, P.B.; Norton, D.A.; Rolfe, J.R.; Sawyer, J.W.D. 2010: Threatened Plants of New Zealand. Christchurch, Canterbury University Press. 471pp.
Heenan, P. B. 1995: A taxonomic revision of Carmichaelia (Fabaceae-Galegeae) in New Zealand (part I). New Zealand Journal of Botany 33: 455-475.
Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 2009 Vol. 11 No. 4 pp. 285-309
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 1 October 2003. Description adapted from Heenan (1995) - see also de Lange et al. (2010).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Carmichaelia hollowayi Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/carmichaelia-hollowayi/ (Date website was queried)