Amaranthus graecizans 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 : 141-142

5. Amaranthus graecizans L. , Sp. Pl. 2: 990. 1753

Type (lectotype designated by Fernald 1945: 139):— U.S.A. Habitat in Virginia, Herb. Clayton No. 442 (BM000051563!, image of the lectotype available at https://data.nhm.ac.uk/object/ca635ca9-9252-42a3-9082-60ec097bc2d6/1641427200000).

= Amaranthus angustifolius Lam., Encycl. [J. Lamarck & al.] 1: 115. 1783, nom. illeg. Art. 52.21 of the ICN ( Turland et al. 2018).

Description:— Herbs 1–8 dm tall, monoecious, annual (therophyte). Stems erect or ascending, ± glabrous (sometimes sparsely pubescent in the distal region), pale to black-brown to reddish, usually branched. Leaves usually green, ovaterhomboidal to lanceolate (decreasing in size towards stem apex), with entire margins, apex acute or obtuse, sometimes mucronate, base cuneate, glabrous, petioled [petiole (1.0–)2.0–5.0(–6.0) cm long]. Synflorescences arranged in axillary glomerules, often reddish. Floral bracts brown-yellowish, lanceolate (1.2–2.0 × 0.3–0.6 mm) as long as or shorter than the perianth, acute, margin entire, glabrous. Staminate flowers with 3 tepals, ovate to lanceolate; stamens 3. Pistillate flowers with 3 tepals, ovate-lanceolate [(1.3–)1.5–2.0 × 0.4–0.7 mm], with acute, and often mucronate apex; stigmas 3. Fruit brown, subglobose [(1.5–)2.0–2.5(–2.7) × (1.0–)1.4–1.5(–1.8) mm], longer than the perianth, rugose, dehiscent. Seed lenticular [1.0–1.3(–1.5) mm in diameter], black to dark-brown.

Chorology:— Paleotemperate taxon native to Europe, Central-Western Asia, and Northern Africa ( Carretero 1990, Akeroyd 1993, Boulos 1999, Ghafoor et al. 1977, Fennane & Tatou 2005, Le Floc’h et al. 2008), it is considered introduced in some European countries, North America, South Africa, and Australia ( POWO 2022a and literature therein). Concerning Saudi Arabia, it is native.

At subspecific rank two main distribution areas can be distinguished, the first one including Central and southern Europe plus North Africa [ subsp. graecizans and subsp. sylvestris (Vill.) Brenan ], the second area being the eastern Europe ( Russia and adjacent territories) plus Central and southern Asia [ subsp. aschersonianus (Thell.) Costea and subsp. thellungianus (Nevski) Gusev ] (see Iamonico 2015: 34).

Occurrence in Saudi Arabia:— See varieties.

Taxonomic annotations:— Amaranthus graecizans is a species morphologically variable, especially regarding the hairiness of stem, the shape of leaves (lanceolate or ovate-rhomboidal), the structure of synflorescence (with or without terminal synflorescence), the apex of bracts and tepals (acute-mucronate or awned), the margin of seed (obtuse or acute), and the dehiscence/indehiscence of fruit. These variability is currently interpreted recognizing four subspecies, i.e. subsp. graecizans, subsp. sylvestris, subsp. aschersonianus , subsp. thellungianus (see e.g., Costea 2003). Based on our field surveys and according to Chaudhary (1998) three subspecies occur in Saudi Arabia. These taxa can be distinguisced as follow:

1. Bracts and tepals awned (awn 0.3–0.7 mm long)................................................................................................ subsp. thellungianus

2. Bracts and tepals mucronate (mucro about 0.1 mm long)..................................................................................................................3

3. Leaf blade lanceolate [2.0–3.0(–4.0) × 0.5–1.0 cm], ratio length/width of the blade 3.0–6.0................................ subsp. graecizans

- Leaf blade ovate-rhomboidal [5.0–6.0 × 2.5–3.0(–3.5) cm], ratio length/width of the blade 1.8–2.2....................... subsp. sylvestris