3. Amaranthus tricolor L., Sp. Pl. 2: 989. 1753 Type (lectotype designated by Townsend 1974: 14):—ASIA. Habitat in India, Herb. Linn. No. 1117.7 (LINN!, image of the lectotype available at https://linnean-online.org/11633/). = Amaranthus melancholicus L., Sp. Pl. 2: 989. 1753. ≡ Amaranthus tricolor var. melancholicus (L.) Lam. & Monnet, Encycl. [J. Lamarck & al.] 1: 115. 1783. Type (lectotype designated by Townsend 1994: 11):—ASIA. Habitat in India, Herb. Linn., No. 1117.4 (LINN!, image of the lectotype available at http://linnean-online.org/11630/). = Amaranthus tristis L., Sp. Pl. 2: 989. 1753. ≡ Amaranthus tricolor var. tristis (L.) Thell. in Asch. & Graebn., Syn. Mitteleur. Fl. [Ascherson & Graebner] 5: 274. 1914. ≡ Amaranthus tricolor subsp. tristis (L.) Aellen in Hegi, Ill. Fl. Mitt.- Eur. 3(2): 495. 1959. Type (lectotype designated by Iamonico 2014: 149):—ASIA. Habitat in China, Herb. Linn., No. 1117.11 (LINN!, image of the lectotype available at http://linnean-online.org/11637/). = Amaranthus mangostanus L., Cent. Pl. I. 32. 1755. ≡ Amaranthus tricolor var. mangostanus (L.) Thell. in Asch. & Graebn. Syn. Mitteleur. Fl. [Ascherson & Graebner] 5: 274. 1914. ≡ Amaranthus tricolor subsp. mangostanus (L.) Aellen, in Hegi, Ill. Fl. Mitt.- Eur. 3(2): 495. 1959. Type (lectotype designated by Iamonico 2014a: 147):—ASIA. Habitat in India, Herb. Linn., No. 1117.10 (LINN!, image of the lectotype available at http://linnean-online.org/11636/). = Amaranthus polygamus L., Cent. Pl. I. 32. 1755. ≡ Amaranthus tricolor subsp. tristis var. polygamus (L.) Aellen in Hegi, Ill. Fl. Mitt.- Eur. 3(2): 495. 1959. Type (lectotype designated by Iamonico 2014a: 148):—ASIA. Habitat in India, Herb. Linn., No. 1117.9 (LINN!, image of the lectotype available at http://linnean-online.org/11635/). Description:— Herbs 8–10 dm tall, monoecious, annual (therophyte). Stems erect or ascending, ± glabrous, green or red, branched (rarely simple). Leaves green, red, red-purpureus or red-yellow mixed, ovate-rhomboidal (4.0–12.0) × 1.4–6.0), with usually entire margins, apex obtuse to emarginate, often mucronate, base cuneate, glabrous, petioled (petiole 2–6 cm long). Synflorescences arranged in axillary glomerules and terminal spike-like, green to reddish. Floral bracts, usually greenish, deltoid-ovate (5.0–6.0 × 0.8–1.8 mm) as long as the perianth, awned, margin entire, glabrous. Staminate flowers with 3 tepals, ovate to lanceolate, apex acute, awned; stamens 3. Pistillate flowers with 3 tepals, ovate (3.0–5.0 × 1.5–2.5 mm); stigmas 2–3. Fruit brown, subglobose to ellipsoidal (2.0–2.5 × 0.8–1.3 mm), shorter than the perianth, rugose, dehiscent. Seed lenticular (about 1.0 mm in diameter), black or brown. Iconography:— Chaudhary (1998: 245, Plate. 127a–f), Bayón (2015: 368, Figura 61). Chromosome number:— 2n = 34, 68, 85. Occurrence in Saudi Arabia:— Cultivated only in Saudi Arabia according to Chaudhary (1998: 238). No wild plants were found by us during the field survey.

Published as part of 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, pp. 135-157 in Phytotaxa 576 (2) on page 140, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280