2021 Favourite Plant Vote candidate profile - Solenogyne christensenii
The 2021 Favourite Native Plant vote will open on 1 October and run for 1 month. In the lead up to the return of this popular vote, NZPCN committee members are profiling some of the plants which they feel need a little more love. To see the full article with all the images see issue 210 of Trilepidea.
Contributor: John Barkla, NZPCN president, connoisseur of diminutive and cryptic dryland plants
Favourite plant candidate: Solenogyne christensenii
Why I have selected this species: This plant was only recently “rediscovered” in the wild and is now known from just one tiny population on the brink of extinction. It’s a small tufted herb (up to 30 mm tall and 50 mm across) originally published under the name Abrotanella christensenii. The new combination was published in a scientific paper last year and represents the only endemic Solenogyne in New Zealand (we have three introduced species). Unfortunately, this ‘one population’ scenario is a theme for several small, poorly known, dryland herbs of Central Otago. The conservation of this suite of threatened plants is complicated by their tiny populations, lack of trend data, and myriad of threats.
Current population: One small population of less than 100 plants (86 at last count) that grows in tiny patches within a 25m2 herbfield on a silty riverbank under dappled shade. Under the New Zealand Threat Classification System, its conservation status, as Abrotanella christensenii, is listed as Nationally Critical qualified ‘DP’ [Data Poor] and ‘EF’ [Extreme Fluctuations] by de Lange et al. (2018).
Distribution: The species is endemic to New Zealand and is restricted to a herbfield under montane shrubland at approximately 280 m above sea level in the upper Clutha Valley of Otago. Petrie (1915) named this species after Charles E. Christensen (1876–1938) who was the first person to collect this species, as Abrotanella christensenii, during his botanical exploration of the vegetation of Hanmer Plain, in North Canterbury. Here it was recorded from “bare spots in dry fescue tussock steppe”. The population at this site, the type locality, is now presumed extinct.
Threats: The single site where this plant is known from is extremely vulnerable to complete loss in a flood event. Loss at this site would mean its extinction in the wild. Other potential future threats include weed competition and destruction of its habitat by fire.
Prospects: A recent survey of other ostensibly suitable lake shore and riverside habitat around the single extant population failed to find any other populations of this species. Although a few plants are held in cultivation, survival of this species in the wild is, at best, precarious. What do we need to do right now? Get familiar with what this plant looks like and find some more. You could start by reading the paper in the Ukrainian Botanical Journal that describes and illustrates the species, and differentiates it from similar and related taxa (de Lange et al. 2020). If no more sites/populations can be found then new populations need to be established using plants held in cultivation and sites that best approximate our understanding of its habitat.
References and further reading:
de Lange, P.J.; Rolfe, J.R.; Barkla, J.W.; Courtney, S.P.; Champion, P.D.; Perrie, L.R.; Beadel, S.M.; Ford, K.A.; Breitwieser,I.; Schonberger, I.; Hindmarsh-Walls, R.; Heenan, P.B.; Ladley, K. 2018: Conservation status of New Zealand indigenous vascular plants, 2017. New Zealand Threat Classification Series 22. Department of Conservation, Wellington. 82 p
de Lange, P.J.; Wang, J.; Barkla, J.W.; Marshall, A. 2020: Solenogyne christensenii, comb. nov. (Asteraceae; Astereae), a new combination for a New Zealand species. Ukrainian Botanical Journal 77(2): 73–80
Petrie D. 1915. New native phanerogams. Transactions & Proceedings of the New Zealand Institute, 47 [volume of 1914]: 48–59. Available at: http://rsnz.natlib.govt.nz/ volume/rsnz_47/rsnz_47_00_000950.html
Posted: 1 September 2021