Amaranthus emarginatus Salzm. ex Uline & W. L.

Raus, Thomas, 2022, Taxonomic, nomenclatural and floristic review of Amaranthaceae of Greece and neighbouring countries, Willdenowia 52 (3), pp. 335-357 : 342-343

11. Amaranthus emarginatus Salzm. ex Uline & W. L.

Bray in Bot. Gaz. 19: 319. 1894 ≡ Euxolus viridis var.

polygonoides Moq. in Candolle, Prodr. 13(2): 274. 1849

≡ Amaranthus ascendens var. polygonoides (Moq.) Thell.

in Mém. Soc. Natl. Sci. Nat. Math. Cherbourg 38: 215.

1912 ≡ Amaranthus lividus subsp. polygonoides (Moq.)

Thell. ex Probst, Wolladventivfl. Mitteleur.: 74. 1949 ≡

Amaranthus blitum subsp. polygonoides (Moq.) Carretero in Anales Jard. Bot. Madrid 41: 276. 1985. – Lectotype

(designated by Hügin 1987: 461): Asia, Indonesia, Java,

1842–1844, Zollinger 1646 ( P P00572006 , plant on the left; isolectotypes: G G00098622 , G GDC00138473 , P

P00572007).

– “ Amarantus polygonoides Zolling. ” Moquin-Tandon in Candolle, Prodr. 13(2): 274. 1849, nom. inval., pro syn.

– “ A[marantus]. emarginatus Salzm. ” Moquin-Tandon in Candolle, Prodr. 13(2): 274. 1849, nom. inval., pro syn.

Remarks — Despite the differing epithets, Amaranthus emarginatus and Euxolus viridis var. polygonoides are homotypic (see Hügin 1987: 461; Bayón 2015: 310; POWO 2022). When Moquin-Tandon (1849: 274) validly published the name E. viridis var. polygonoides , he cited in synonymy “ A. emarginatus Salzm. ”, an unpublished collector’s name for plants that Philipp Salzmann had collected in Brazil in 1830 (see Röse 1853). Forty-five years later, Uline & Bray (1894: 319) used this binomial as a replacement name when they raised Moquin-Tandon’s taxon to specific rank, because the name A. polygonoides had already been published by Linnaeus for a different, Caribbean amaranth ( Linnaeus 1759: 27; Iamonico 2011; POWO 2022). The type of A. emarginatus is therefore the same as that of E. viridis var. polygonoides ( Shenzhen Code Art. 7.4). Hügin (l.c.) chose the specimen Zollinger 1646 in Paris (P00572006) as the lectotype because it was at Moquin-Tandon’s hand in the description of E. viridis var. polygonoides according to the pertinent handwritten herbarium label. The lectotype is the plant on the left, collected by Zollinger, who had wrongly assumed that it was probably A. polygonoides L.; the plant on the right was collected in Brazil by Salzmann (Hügin l.c.). The attempted second-step lectotypification by Bayón (l.c.), who chose the duplicate specimen of Zollinger 1646 in Paris (P00572007), is ineffective ( Shenzhen Code Art. 9.19) because it was already clear which of the two specimens in Paris was designated as the lectotype by Hügin (l.c.).

The species is native to the tropics of both hemispheres ( Thellung 1914: 320; Hügin 1987: 461; Bayón 2015: 310, 2020: 51) and is introduced to warm-temperate parts of North America, Europe and N Africa ( Townsend 1985: 35; Iamonico 2015a). Amaranthus emarginatus was sometimes merged with A. blitum L. and ranked as a subspecies or variety of the latter ( Townsend 1985: 35, “after some vacillation”; Carretero 1990; Lambinon & Rastetter 1993; Bayón 2015, 2020). The two taxa are however of disparate origin: A. emarginatus pantropical vs A. blitum Old-World Mediterranean; they are reasonably treated as separate species in order to reflect their different chorology and evolutionary history ( Iamonico 2016a).

On the basis of growth form, leaf size and inflorescence arrangement, two infraspecific taxa of Amaranthus emarginatus can be distinguished in Greece. They occupy clearly different ecological niches related to the capability to endure water stress, such as temporary inundation, which led Loos (2010) to accept them as distinct species, while Iamonico (2015b) treated them at varietal rank, following Lambinon & Worms (1993). In Greece they behave as ecologically disjunct subspecies, in taxonomic accordance with Hügin (1987) and Raus (1997).

1. Plant prostrate, usually appressed to surface of substrate; leaves (1.0–)2.0–3.0 × (0.5–)1.0– 1.5 cm; inflorescence predominantly in axillary glomerules, terminal spike if present short and thick, up to 2.0 cm long... Amaranthus emarginatus subsp. emarginatus

– Plant ascending, mature stems sometimes overhanging; leaves (2.0–)3.0–4.0(–4.5) × (1.2–) 1.5–2.5 cm; inflorescence predominantly in long and slender, usually thin and flexuous axillary and terminal spikes 7.5–12.0 cm long............................. Amaranthus emarginatus subsp. pseudogracilis