Sophora chathamica
Poisonous plant
Past favourite plant finalist
Common names
kōwhai, coastal kōwhai
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Trees & Shrubs - Dicotyledons
Simplified description
An early-flowering kowhai tree, bearing leaves to 150mm long that have leaflets 6-16mm long by 4-8mm wide that slightly overlap and get smaller towards the leaf tip. Has bunches of drooping yellow flowers and dry, ridged and knobbly seed pods 50-180mm long, containing hard yellow seeds. Juvenile and adults similar.
Flower colours
Yellow
Detailed description
Tree up to 20 m tall, with one or more trunks. Branches spreading to upright. Juveniles weakly flexuose. Leaves on seedlings and juveniles moderately to densely leafy, 4.4-9 x 4.4-7.5 mm, orbicular to very broadly obovate, crowded, usually overlapping. Adult leaves up to 150 mm long, imparipinnate, usually pubescent, hairs, straight, appressed. Leaflets 25-55, crowded and overlapping, 6-16 x 4-8 mm, broadly elliptic, broadly obovate, broadly ovate, obovate to orbicular, distal leaflets usually smaller than proximal. Inflorescences racemose with up to 11 flowers. Calyx 8-10 x 10-13 mm, cupulate. Flowers yellow, keel petal blade 29-43 x 9-11 mm, wing petal blade 25-42 x 9-11 mm, standard petal blade 25-34 x 20-25 mm; petals with distinct claws 4-6 mm long. Fruit 50-180 mm long, 4-winged, brown, with up to 12 seeds. Seeds 5.5-8 x 4.-5. mm, oblong, elliptic to orbicular, yellow to light yellow-brown.
Similar taxa
Distinguished from all other Kowhai species by the absence of a divaricating/filiramulate juvenile stage; with leaflets 6-16 x 4-8 mm; and by the distal leaflets usually smaller than proximal, crowded and overlapping (especially toward distal end), with leaflets broadly elliptic, broadly obovate, broadly ovate, obovate to more or less orbicular, with all parts moderately hairy. Tends to flower earlier in spring than other kowhai tree species and is even known to flower from mid-winter.
Distribution
Endemic. A primarily coastal species known from North, South and Chatham Islands but probably only indigenous to the northern half of the North Island, where it is common in the west from the Tongaporutu River to Te Paki. In the east, it is abundant south to about Thames and, so far, it has not been reported growing naturally south and east of there. Very common around Auckland, the Hauraki Gulf and from Port Waikato south to Kawhia. There are some inland occurrences in the lower Waikato Basin. Disjunct occurrences around Wellington, the Chatham Islands and Whanganui Inlet may result from deliberate plantings by the Maori.
Habitat
Primarily a species of coastal forest, often on cliff faces or banks overlooking estuarine rivers or inlets. Occasionally found in swamp forest.
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 | Not Threatened
Threats
The main threat that faces all wild New Zealand kowhai species is the risk of hybridisation, 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. However, S. chathamica seems to be very common throughout its range, and is adequately protected within a range of reserves and land set aside for conservation purposes. The nativity of the Chatham Island populations is not clear and, though assumed to be planted by Maori, this assertion needs further study and, as the trees are culturally significant they require direct management. Few, if any, Chatham Island plants can be said to exist in truly secure habitats.
Detailed taxonomy
Family
Fabaceae
Synonyms
Sophora microphylla var. chathamica (Cockayne) Yakolev, Sophora microphylla subsp. microphylla var. chathamica (Cockayne) Yakolev
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
(June) - July-November
Fruiting
October-November
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.
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. Very commonly sold in garden centres, where it is often sold as either S. microphylla or S. tetraptera. Some plants with a superficial resemblance to S. chathamica and offered by nurseries usually as S. microphylla or S. tetraptera have, upon closer inspection, turned out to be the closely related Chilean pelu (S. cassioides).
Etymology
sophora: After the Arabic name for a similar tree
chathamica: From the Chatham Islands
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.
SOPCHA
Chromosome number
2n = 18
Previous conservation statuses
2017 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | 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.; Ogle, C. (Year at time of access): Sophora chathamica Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/sophora-chathamica/ (Date website was queried)