Lepidium obtusatum
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
White
Detailed description
Glabrous decumbent to semi-erect herb forming circular patches up to 300 mm diam. Stems stout, fleshy, somewhat flexuous. Rosette and basal leaf petioles, broad, flat up to 80 mm long. Lamina 30-70 x 5-20 mm, fleshy, succulent, oblong-cuneate, obovate, coarsely crenate-serrate, dark green. Cauline leaves subsessile to sessile, lamina (5-)10-20(-50) x (3-) 5(-15) mm, fleshy-succulent, obovate, ovate to broadly ovate, crenate, rarely toothed, dark green. Inflorescence a terminal raceme (20-)3(-50) mm long, these numerous. Flowers 3-4 mm diam.; pedicels 3-5 mm, erecto-patent sometimes decurved; sepals broadly ovate-oblong, c.1.5. mm long; petals white, obovate < or = to sepals. Stamens 4(-6). Silicle 4.5-5.5 x 4-4.5 mm, broadly ovate, shallowly notched at apex, slightly winged; style very short; stigma = notch. Seeds broadly ovoid to triangular, orange brown, 2 x 2 mm.
Similar taxa
Traditionally allied to the Lepidium banksii Kirk, from which it is easily distinguished by the decumbent to suberect growth habit, obovate, oblong-crenate leaves, very long petiolate rosette leaves, and glabrous pedicels. Recently obtained (2005) nrDNA ITS/ETS sequences suggest that although nested within the L. oleraceum group of Lepidia it was not closely allied to either L. banksii or L. oleraceum s.s. with its sister taxon Lepidium panniforme (de Lange et al. 2013).
Distribution
Endemic. North Island, Wellington (Seatoun to Fort Dorset). Not seen since 1950 (on the Miramar peninsula in Wellington) and now presumed extinct (de Lange 2005). Not known in cultivation. First collected in the Wellington area prior to 1892.
Habitat
Plants grew mainly in fine beach gravel and stable talus slopes between Seatoun and Point Dorset. At this site it may also have grown on cliff faces.
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 | Extinct
Threats
The Wellington population seems to have been eliminated through a combination of habitat destruction and over collection by people. It is not clear why this species disappeared from the Waitakere Coastline.
Detailed taxonomy
Family
Brassicaceae
Synonyms
None
Taxonomic notes
Plants attributed to Lepidium obtusatumthat had been collected from the Manukau Heads are now referred to another extinct species L. amissum (de Lange et al. 2013).
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
December - July
Fruiting
December - July
Life cycle and dispersal
Mucilaginous seeds are dispersed by attachment and possibly wind and water (Thorsen et al., 2009).
Propagation technique
Not Applicable. However, seed obtained from a 1938/39 (exact year of collection not clear) and sown in 1993 took up water and began to germinate but then died. Possibly this experiment should be repeated but as an extinct species, seed is obviously limited.
Other information
Notes on its status
Only one account of this species appearance when alive is known, and that suggests it was a very fleshy, succulent herb with dark green leaves (de Lange et al. 2013). The species appears to have alway been of rather restricted occurrence and its loss seems to have been due to a combination of excessive plant collection by botanists (de Lange 2005), weed invasion and destruction of the main population as a consequence of gravel extraction (de Lange et al. 2013). There have been numerous surveys for this species in the Wellington area and it has not been seen in any of its haunts or likely habitats further afield since 1950. Indications are that it was already very uncommon localised endemicwhen it was discovered.
Etymology
lepidium: Scale-shaped (pods)
obtusatum: Obtuse, or blunt
Previous conservation statuses
2017 | Extinct
2012 | Extinct
2009 | Extinct
2004 | Extinct
Referencing and citations
References and further reading
de Lange, P.J.; Heenan, P.B.; Houliston, G.; Rolfe, J.R.; Mitchell, A.D. 2013: New Lepidium (Brassicaceae) from New Zealand. Phytokeys 24:1-147pp. , doi: 10.3897/phytokeys.24.4375.
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 11: 285-309
Attribution
Fact Sheet by P.J. de Lange: Description adapted from de Lange et al. (2013).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Lepidium obtusatum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/lepidium-obtusatum/ (Date website was queried)