Can, İmrak, Kılıçarslan, Karaaslan and Özüdoğru report in Acta Physiologiae Plantarum (2026) the first element-by-element survey of the Noccaea aucheri species complex across its entire distribution range. Twelve populations were collected in June–July of 2017 and 2019 from serpentine sites in six Anatolian provinces — Kayseri, Adana, Mersin, Konya, Sivas and Erzincan — between 1,339 and 2,960 m elevation, and screened with X-ray fluorescence against a 17-element matrix in two leaf types: older basal rosette leaves and younger stem leaves. The complex comprises three taxa: N. sempervivum (populations 1–5, Taurus range), N. aucheri sensu stricto (6–11, inner Anatolia) and N. mummenhoffiana (population 12, Keşiş Mountain, 2,960 m).
The headline: Ni past 1% of leaf mass, Zn left behind
The grand means across all twelve populations are unambiguous (Table 2 of the paper). Leaf nickel averages 11,463 ± 1,399 ppm (≈1.15% of mass) in basal leaves and 13,887 ± 1,937 ppm (≈1.39%) in stem leaves — an order of magnitude above the conventional 1,000 µg g⁻¹ dry-weight hyperaccumulation threshold, and in a genus whose record holder, Noccaea cappadocica, reached 48,700 µg g⁻¹ in a herbarium specimen screened by the same XRF approach (Jakovljević et al. 2024, cited by the authors; see our /species/noccaea-cappadocica/ record).
What is more telling is what does not move. Zinc sits at 54.3 ± 8.1 ppm (basal) and 52.8 ± 7.3 ppm (stem) — ordinary plant background, not accumulator territory. This is the opposite profile of the famous Noccaea caerulescens (our Ni record, our Zn record), which hyperaccumulates Zn and Cd as readily as Ni depending on population. The Anatolian complex is a one-metal specialist, and that specificity is itself mechanistically interesting: it points to a committed nickel-transport-and-storage machinery (serpentine-ecotype HMA/NAAT-type pathways rather than the broad-spectrum ZIP/MTP handling of Zn) that does not leak over into neighbouring divalent cations. Two more numbers frame the serpentine story. Calcium runs 20,412 ± 3,106 ppm (basal) and 23,918 ± 2,197 ppm (stem) against magnesium at only 5,907 ± 557 and 4,897 ± 423 ppm — a leaf Ca:Mg near 4:1 built on soils famous for exactly the reverse ratio, a signature of the calcium hunger that defines serpentine adaptation. The multivariate structure (Table 3) is dominated by exactly this elemental phenotype: on a 17-element PCA, the first two components carry 60.2% of variance in basal leaves and 51.8% in stem leaves.
The non-obvious implication: a prospecting map that doubles as a red-list file
Range-wide XRF screening sounds like taxonomy with a gadget. It is actually the cheapest decision tool both sides of the nickel economy have. For agromining, Türkiye is one of the planet’s great nickel hyperaccumulation theatres — Reeves and Adıgüzel’s classic survey counts at least 59 taxa capable of hyperaccumulating nickel in Türkiye and adjacent areas (Reeves & Adıgüzel, Turk J Biol 32:143–153, cited by the authors), and the country holds major laterite and ophiolite nickel resources now attracting mining investment. Knowing which Noccaea populations push past 1% Ni, and where they sit relative to roads, water and ore bodies, is step zero of any phytomining feasibility study — see the /nickel hub for the element’s agromining context. But the same coordinates work in the opposite direction. Every population in Table 1 is a serpentine endemic restricted to an “ultramafic island”, and several of these sites sit in ophiolite belts with active or permitted nickel and chromite extraction. The most range-restricted taxon in the survey — N. mummenhoffiana, represented by a single collection at 2,960 m on Keşiş Mountain — is precisely the kind of plant that disappears when its one mountain is mined, and precisely the kind of plant nobody lists because nobody has quantified it. A table of XRF values plus GPS coordinates is, accidentally, IUCN-ready evidence.
The sober ledger
Read this as what it is: a screening study, partially legible. The article is paywalled — the methods and discussion prose are not openly retrievable, and what is verifiable are the standalone tables and the reference list — so three limits must be stated plainly. First, the XRF ppm values are quoted as measured by the instrument; the canonical hyperaccumulation criterion is defined on dry mass, and whether the readings were calibrated against an ICP technique (as the Jakovljević herbarium-XRF protocol they cite explicitly does) is stated only in the paywalled methods. The 11,000–14,000 ppm magnitude is so far above any plausible calibration artefact that the hyperaccumulator conclusion is safe; the third decimal is not. Second, the grand means pool three taxa and two leaf ages: basal rosette leaves are older than stem leaves at sampling, and the basal-enrichment pattern in Fe (835 vs 585 ppm) is a classic leaf-age and surface-dust signature, so the basal-versus-stem trends in Table 2 conflate position, age and species identity — the PCA’s PC1 likely tracks those confounds rather than soil chemistry. Third, sample sizes drift between analyses (Ni in stem leaves is n = 11 where every other element is n = 12; the PCA uses n = 10 basal and 11 stem) with no explanation visible in the open material, and trace Sn at ~11 ppm sits near the practical comfort zone of handheld XRF. None of this overturns the result; all of it bounds how far the result reaches. And note what the study does not measure at all: biomass, shoot yield, or soil Ni — the other half of the agromining equation.
Why it still matters
The single biggest gap between hyperaccumulator catalogues and working phytomining is not discovery but characterization at range scale — knowing whether a species is a consistent 1%-Ni machine across its distribution or a lucky outlier at one site. This paper supplies that baseline for one of Anatolia’s flagship complexes, with open tables, and it does so with an instrument a survey team can carry in a backpack. The obvious next step is a paired ICP-calibrated, per-population follow-up on the same herbarium vouchers, plus biomass trials on the highest-Ni sites — and, in parallel, a conservation assessment for the single-mountain mummenhoffiana population before the nickel economy gets there first. Both agendas start from exactly this table.
Provenance: article paywalled (publisher elides even the abstract); analysis bounded to the open standalone Tables 1–3, the reference list, and cited prior literature (Reeves & Adıgüzel 2008; Jakovljević et al. 2024), each independently re-retrieved. Every load-bearing number was verified against the primary source by three independent reviewers with zero discrepancies; paper-internal limitations (XRF dry-mass calibration unverifiable from open material, pooled taxa and leaf-age confounds, n drift between analyses) are reported above rather than smoothed over; methods and limits at /methodology/.