Amaranthus spinosus 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 : 148

8. Amaranthus spinosus L ., Sp. Pl. 2: 991. 1753

Type (lectotype designated by Fawcett & Rendle 1914: 103):—ASIA. Habitat in Indiis , Herb. Linn. No. 1117.27 (LINN!, image of the lectotype available at http://linnean-online.org/11653/) .

Description:— Herbs 1–85(–120) dm tall, monoecious, annual (therophyte), rarely biennial. Stems usually erect, ± glabrous (sometimes sparsely pubescent in the inflorescence region), white to white-greenish, much branched. Leaves green (usually pale green), ovate, elliptic to spathulate (3.5–6.0 × 1.5–3.0 cm in the main axis, greater than the leaves on the branches), often with undulate margins (sometimes with a white marginal vein), apex obtuse and mucronate, base cuneate, glabrous (rarely pubescent on the veins), petioled (petiole 1.6–3.0 cm long). Synflorescences arranged in axillary glomerules, light green. Floral bracts greenish, ovate-lanceolate [(2.0–)3.0–4.0(–6.0) × 0.3–0.6 mm], 2(–2.5) times longer than the perianth, awned, margin entire, glabrous. Staminate flowers with 3 tepals, lanceolate; stamens 3. Pistillate flowers with 3 tepals, linear to lanceolate [0.9–1.1 × 0.3–0.4(–0.5) mm], with acute apex; stigmas 3. Fruit brownish-black, ellipsoidal [(1.2–)1.4–1.8 × 1.0–1.2(–1.4) mm], as long as or slightly longer than the perianth, rugose when dry, dehiscent. Seed lenticular [(0.8–)0.9–1.1(–1.3) mm in diameter], black to brownish-black.

Iconography:— Beck (1909: Tab. 297, figures 3–5); Chaudhary (1998: Plate. 127g –j), Bayón (2015: 296, Figura 15).

Phenology:— Flowering time June ( Al-Turki et al. 2000).

Habitat and elevation:— Human-made habitat, about sea level ( Al-Turki et al. 2000).

Chromosome number:— 2n = 34 ( Al-Turki et al. 2000: 341), 68.

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

Occurrence in Saudi Arabia ( Fig. 10 ):— Bisha ( Abbas et al. 2020), Jizan ( Al-Turki et al. 2000, Aljieddani et al. 2021). No finding was done during the filed surveys. Further researches are necessary to verify the distribution of A. spinosus in the country.

Figures

FIGURE 10. Map of Amaranthus spinosus.