Sophora tetraptera
Poisonous plant
Common names
kōwhai, large-leaved kōwhai
Biostatus
Native
Category
Vascular
Structural class
Trees & Shrubs - Dicotyledons
Simplified description
A commonly-grown kowhai tree bearing leaves 100-220 long that have widely-spaced greyish-green leaflets 15-40mm long and with bunches of drooping yellow flowers and dry ridged and knobbly seed pods 100-280mm long containing hard yellow seeds. Juveniles and adults similar. Naturally occurring in the eastern North Island, Taupo and Waikato River.
Flower colours
Yellow
Detailed description
Tree up to 15 m tall, trunk 0.6-1 m diam., often several arising from ground. Branches spreading, sometimes pendulous. Branchlets clad in golden yellow or grey tomentum. Juvenile plants not divaricating or flexuous, exhibiting an erect growth, non-interlacing habit from germination. Leaves 100-150(-220) mm, imparipinnate, moderately hairy, hairs, straight, appressed. Leaflets 10-20(-25) pairs, 15-35(-40) x 5-8 mm, well spaced, never overlapping or crowded, narrowly ovate to elliptic-oblong. Inflorescences racemose with up to 10 flowers. Calyx 10-20 x 10-15 mm, cupulate. Flowers golden-yellow, keel petal blade 20-50(-60) x 10-16(-18) mm, wing petal blade 25-50(-62) x 10-16 mm, standard petal blade 30-35(-42) x 18-30(-35) mm; petals with distinct claws 6-8 mm long. Fruit (100-)200(-280) mm long, broadly 4-winged, brown, with 6-12 or more seeds. Seeds 6.5-9(-10) x 6-7.5 mm, oblong, elliptic to orbicular, yellow to light yellow-brown.
Similar taxa
Easily distinguished from all other Kowhai species by the very large and wide grey-green leaves, with the leaflets 15-35 mm x 5-8 mm, ovate to elliptic -oblong, densely clad in silky, straight, appressed hairs. From the members of the S. microphylla complex it can also be distinguished by the flowers whose standard is distinctly less than the length of the wings.
Distribution
Endemic. Known in a natural state only from the eastern portion of the the North Island from East Cape south to the Wairarapa, extending west toward Taihape, Lake Taupo and along the Waikato River to about Lake Karapiro. However, extensively planted outside this range and often naturalising.
Habitat
Widespread and common from coastal forested habitats inland along rivers and within associated low scrub and forest. Common around lake margins (especially Lake Taupo) and on ignimbrite cliffs bordering the upper Waikato River. Although a primarily lowland species it can occur in montane riparian 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 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. tetraptera seems to be very common throughout its range, and is adequately protected within a range of reserves and land set aside for conservation purposes.
Detailed taxonomy
Family
Fabaceae
Synonyms
Edwardsia grandiflora (J.S.Mill.) Salisb., Edwardsia tetraptera (J.Mill.) W.R.B.Oliv.
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
(September-) October-December
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.
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. Some plants sold by nurseries are possibly hybrids with S. microphylla.
Etymology
sophora: After the Arabic name for a similar tree
tetraptera: Four winged
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.
SOPTET
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
Allan, H.H. 1961: Flora of New Zealand. Vol. I. Wellington, Government Printer.
Anonymous. 1944. Kowhai. Wellington Botanical Society Bulletin 9: 4-5
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange (31 July 2004). Description adapted from Allan (1961).
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.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Sophora tetraptera Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/sophora-tetraptera/ (Date website was queried)