Amaranthus caudatus 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 : 148-149

9. Amaranthus caudatus L. , Sp. Pl. 2: 990. 1753

Type (lectotype designated by Towsend 1974: 10):—UNKNOWN ORIGIN. Habitat in Perù, Persia, Zeylonia, Herb. Linn. No. 1117.26 (LINN!, image of the lectotype available at http://linnean-online.org/11652/) .

Description:— Herbs 8–15 dm tall, monoecious, annual (therophyte). Stems erect, glabrous (pubescent in the distal part), red to purple, branched. Leaves red, ovate, rhomboidal 5.0–15.0 × 2.0–8.0 cm), with entire margins, apex obtuse or acute, mucronate, base cuneate, often pubescent, petioled (petiole 1.0–12.0 cm long). Synflorescences terminal, spike-like, up to 60–70 cm long, red to purple, pendulous (terminal florescence 30 cm long or more). Floral bracts greenish to reddish, ovate to lanceolate-linear (3.0–4.0 × 0.8–1.5 mm) longer than the perianth, acute, awned, margin entire, glabrous. Staminate flowers with 5 tepals, ovate; stamens 5. Pistillate flowers with 5 tepals, lanceolate-spathulate (1.0–2.5 × 0.3–1.3 mm), with acute (in this case mucronate) or obtuse (sometimes emarginate) apex; stigmas 3. Fruit brownish, globose (1.5–2.5 × 1.4–1.9 mm), as long as or longer than the perianth, smooth to rugose, dehiscent. Seed lenticular (1.0– 1.5 mm in diameter), dark-brown to brownish-black.

Iconography:— Beck (1909: Tab. 297, figures 1–2), Bayón (2015: 277, Figura 6).

Phenology:— Flowering time december.

Habitat and elevation:— Dry and rocky places, human-made habitat, around 1700 m a.s.l.

Chromosome number:— 2n = 34, 68.

Alien status:— Neophyte species native to South America ( Argentina, Equador, Peru, and Bolivia), it can be considered as casual in Saudi Arabia (Makkah).

Occurrence in Saudi Arabia ( Fig. 11 ):— According to Chaudhary (1998: 236) this species would be cultivated only in Saudi Arabia (as ornamental plant). Despite no wild plants were found by us during the field survey, we traced one specimen at IND, so confirming that the species occurs in Saudi Arabia .

Specimina visa selecta:— SAUDI ARABIA, Makkah, about 5 km N of Taif , dry, rocky hillside, military base, 1720 m, 11 February 1977, leg. Humbles 100032, det. Johnson (IND0088369!) .

Figures

FIGURE 11. Map of Amaranthus caudatus.