Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia Author Hassan, Walaa A. Author Al-Shaye, Najla A. 0000-0002-0447-8613 Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh 11671, Saudi Arabia & naaalshaye @ pnu. edu. sa; https: // orcid. org / 0000 - 0002 - 0447 - 8613 naaalshaye@pnu.edu.sa Author Alghamdi, Salma 0000-0001-7716-2233 Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh 11671, Saudi Arabia & saatalghamdi @ pnu. edu. sa; https: // orcid. org / 0000 - 0001 - 7716 - 2233 saatalghamdi@pnu.edu.sa Author Korany, Shereen M. 0000-0002-9355-3952 Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh 11671, Saudi Arabia & smkorany @ pnu. edu. as; https: // orcid. org / 0000 - 0002 - 9355 - 3952 smkorany@pnu.edu.as Author Iamonico, Duilio 0000-0001-5491-7568 Ce. R. S. I. Te. S., University of Rome Sapienza, viale XXIV Maggio 7, 04100 - Latina, Italy & duilio. iamonico @ uniroma 1. it; https: // orcid. org / 0000 - 0001 - 5491 - 7568 & Authors that contributed equally to the work text Phytotaxa 2022 2022-12-20 576 2 135 157 http://dx.doi.org/10.11646/phytotaxa.576.2.1 journal article 53324 10.11646/phytotaxa.576.2.1 1a9bd59f-7293-432f-b3c1-6df0bc659474 1179-3163 7461280 7. Amaranthus blitoides S.Watson, Proc. Amer. Acad. Arts 12: 273. 1877 Type ( lectotype designated by Fernald 1945: 139 ):— U.S.A. Iowa : Ames, gravelly or sandy soils especially around buildings and along roads, Bessey s.n. (GH00036983!, image of the lectotype available at https://kiki.huh.harvard.edu/databases/specimen_search.php? mode=details&id=58020) . Description:— Herbs (0.4–)1–5 (rarely up to 10) dm tall, monoecious, annual (therophyte). Stems prostrate-ascending, glabrous (rarely sparsely pubescent), pale green to brown, branched. Leaves usually green (sometimes with a central whitish spot), oblong-lanceolate to obovate-spathulate [1.0–3.0(–4.0) × (0.3–)0.5–1.0(–1.5) cm], sometimes fleshy, with entire or undulate margins, apex acute or rounded, often mucronate, base cuneate, glabrous, with marginal white vein, petioled (petiole 0.5–1.8 cm long). Synflorescences arranged in axillary glomerules, reddish or green. Floral bracts green or greenish, ovate to lanceolate (1.3–3.0 × 0.4–0.7 mm ), shorter than the longest perianth segments, acute, margin entire, glabrous. Staminate flowers with 3(–4) tepals, ovate to lanceolate; stamens 3. Pistillate flowers with (4–)5 unequal tepals, lanceolate, elliptic [the greater 1.5–2.5(–3.5) × (0.7–)1.0– 1.2 mm ], with acute to acuminate, and mucronate apex; stigmas 3. Fruit brown or reddish, ellipsoidal (2.0–2.2 × 1.0– 1.4 mm ), as long as or longer than the tepals, usually smooth, dehiscent. Seed lenticular ( 1.5–1.7 mm in diameter), black. Occurrence in Saudi Arabia :— Jizan [first record, var. blitoides (see below)], Makkah ( Iamonico 2016c ) .