Sophora microphylla
Poisonous plant
Past favourite plant finalist
Common names
kōwhai, weeping kōwhai, small-leaved kōwhai
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Trees & Shrubs - Dicotyledons
Simplified description
A common kowhai tree bearing leaves 30-50mm long that have spaced equal-sized leaflets 4.5-12.5mm long and with bunches of drooping yellow flowers and dry ridged and knobbly seed pods 50-200mm long containing hard yellow seeds. Juveniles with zig-zagging branches.
Flower colours
Yellow
Detailed description
Tree up to 25 m tall, usually a single trunk. Branches weeping, and spreading. Juveniles divaricating and/or strongly flexuose, and interlacing. Leaves on seedlings sparsely to moderately leafy, 3-5.8 x 2.3-4.9 mm, broadly obovate to orbicular, glabrous to sparely pubescent, distant, not crowded or overlapping. Adult leaves up to 150 mm long, imparipinnate, moderately to sparsely hairy, hairs, straight, appressed. Leaflets 30-50, not crowded or overlapping, distant, 4.5-12.5 x 2.3-5.7 mm, elliptic, broadly elliptic, obovate to ovate, sometimes orbicular, distal and proximal leaflets of similar size. Inflorescences racemose with up to 7 flowers. Calyx 5-11 x 7-10 mm, cupulate. Flowers yellow, keel petal blade 18-50 x 7-13 mm, wing petal blade 18-50 x 6-11 mm, standard petal blade 20-35 x 14-25 mm; petals with distinct claws 4-8 mm long. Fruit 50-200 mm long, 4-winged, brown, with up to 12 seeds. Seeds 5.5-8.5 x 4.-5.5 mm, oblong, elliptic to orbicular, yellow to light yellow-brown.
Similar taxa
Can be distinguished from the other Kowhai species by the divaricating/filiramulate juvenile and arborescent adult, leaves > 30 mm, leaflet pairs > 6, these sparsely to moderately hairy, with the distil and by the obvious petiolule.
Distribution
Endemic. Throughout the main islands of New Zealand but scarce in parts of Northland.
Habitat
In the North Island, especially the northern half this is a species of mainly riparian forest. South of about Hamilton it can be found in a diverse range of habitats from coastal cliff faces and associated wetlands to inland grey scrub communities. Scarce to absent over large parts of the eastern North Island from about East Cape south to the northern Wairarapa.
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 | Not Threatened
Threats
The main threat that faces all wild New Zealand kowhai species is the risk posed through planting for revegetation and horticultural purposes of hybrid material, foreign species, such as the Chilean Pelu (S. cassioides) and also of kowhai species outside their natural range. In many places S. microphylla occurs as isolated stands within otherwise cleared alluvial forest, and in this situations the loss of trees over time is inevitable. The species is genuinely uncommon in Northland, and in that area inadequately represented within reserves and other conservation land.
Detailed taxonomy
Family
Synonyms
Edwardsia microphylla (Aiton) Salisb., Edwardsia grandiflora var. microphylla (Aiton) Hook.f., Sophora tetraptera var. microphylla (Aiton) Hook.f.; Sophora microphylla Aiton var. microphylla; Sophora microphylla Aiton subsp. microphylla; Sophora microphylla Aiton subsp. microphylla var. microphylla
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
(May-) August-October
Fruiting
October -May
Propagation technique
Easy from seed, provided the hard seed shell is nicked first with a knife or rubbed with sandpaper to expose the endosperm. Soaking seed treated this way overnight often helps speed up germination. Can be grown with difficulty from cuttings.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
FACU: Facultative Upland
Occasionally is a hydrophyte but usually occurs in uplands (non-wetlands).
Other information
Poisonous plant
All parts of the plant but especially the ripe yellow seed are poisonous. Because the seed are hard they will take a lot of chewing to cause harm, and also will need to be consumed in large quantities to effectively poison a human. If the seed are crushed before eating it is more likely that they will cause harm. The major toxin is Cytisine and symptoms of poisoning include nausea, vomiting, increased heart rate, twitching of muscles or loss of coordination. Onset of these symptoms may occur within one hour. In extreme cases symptoms include paralysis and respiratory failure. Click on this link for more information about Poisonous native plants.
Cultivation
Commonly available at most commercial nurseries. A popular native tree for larger gardens. However many plants sold by nurseries are hybrids with either S. chathamica or S. tetraptera.
Etymology
sophora: After the Arabic name for a similar tree
microphylla: Small leaf
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.
SOPMIC
Chromosome number
2n = 18
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 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Regional conservation status of indigenous vascular plants in Otago” Jarvie S et al. (2024) report.
Otago: 2024 | Regionally Not Threatened
Referencing and citations
References and further reading
Anonymous. 1944. Kowhai. Wellington Botanical Society Bulletin 9: 4-5
Heenan, P.B.; de Lange, P. J.; Wilton, A. D. 2001: Sophora (Fabaceae) in New Zealand: taxonomy, distribution, and biogeography. New Zealand Journal of Botany 39: 17-53
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange (31 July 2004). Description adapted from Heenan et al. (2001).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Sophora microphylla Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/sophora-microphylla/ (Date website was queried)