Amaranthus viridis L.

Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, Phytotaxa 576 (2), pp. 135-157 : 141

4. Amaranthus viridis L. , Sp. Pl., ed. 2. 2: 1405. 1763

Type (lectotype designated by Fawcett & Rendle 1914: 131):—UNKNOWN ORIGIN. Habitat in Europa , Brasilia, Herb. Linn. No. 1117.15 (LINN!, image of the lectotype available at http://linnean-online.org/11641/) .

Description:— Herbs 1–7(–8) dm tall, monoecious, annual (therophyte). Stems erect, glabrous, green to brownish, branched. Leaves black-green, ovate, rhomboidal [(2.0–4.5) × (1.5–)2.0–7.0 cm], with entire (rarely undulate) margins, apex obtuse or rounded (rarely slightly emarginate) and sometimens mucronate, base usually cuneate, usually glabrous, petioled [petiole 1.5–5.0 cm long]. Synflorescences terminal, spike- or panicle-like (sometimes axillary glomerules also occur), the main florescence 3–4 cm long, green to brown, usually thin (5–7 mm in diameter). Floral bracts yellowish or greenish, ovate to lanceolate [0.5–1.0 × 0.4–0.7 mm], shorter (up to ⅓) than the perianth, acuminate, margin entire, glabrous. Staminate flowers with 3 tepals, ovate; stamens 3. Pistillate flowers with 3 tepals, ovatelanceolate or obovate-spathulate (1.2–1.5 × 0.3–0.6 mm), with rounded apex (sometimes acute), mucronate or not; stigmas (2–)3. Fruit brownish, subglobose [(1.2–)1.4–1.7(–1.9) × 1.4–1.6(–1.8) mm] as long as or slighly longer (up to ¼) than the perianth, clearly rugose, indehiscent. Seed lenticular (0.8–1.2 mm in diameter), black or brownish-black.

Iconography:— Chaudhary (1998: 239, Plate. 129b), Bayón (2015: 371, Figura 64).

Phenology:— Flowering time february.

Habitat and elevation:— Human-made habitat, 400–600 m a.s.l.

Chromosome number:— 2n = 34.

Alien status:— Neophyte species native to South America, it can be considered as naturalized in Saudi Arabia (see also Chaudhary 1998).

Occurrence in Saudi Arabia ( Fig. 3 ):— Al hudud ash Shamaliyah ( Osman & El-Ameid Abedin 2019), Bisha ( Abbas et al. 2020), Jizan, and Taif ( Abdullah et al. 2017).

Taxonomic annotation:— The name Amaranthus gracilis Desf. was cited by Mandaville (2011) as synonym of A. viridis . Desfontaines’ name was widely discussed by Iamonico (2016b) who reached to the conclusion that it is a nomen ambiguum published by Desfontaines (1804) as nomen novum pro Chenopodium caudatum Jacq. The latter Jaquin’s name was proposed as nomen rejectendum by Iamonico et al. (2015).

Specimina visa selecta:— SAUDI ARABIA, Jizan, human-made habitat, (coastal plain) 5–15 m a.s.l., 17 February 2021, leg. Masrhai et Al-shaye (PNUH), det. Masrhai, conf. Iamonico ( RO!) .

Figures

FIGURE 3. Map of Amaranthus viridis.