Enceliopsis argophylla

Enceliopsis argophylla, commonly known as the silverleaf sunray,[2] is a North American species of flowering plant in the daisy family. Other common names include nakedstem sunray and naked-stemmed daisy. It is native to the southwestern United States: Arizona (Mohave County), Nevada (Clark County), and Utah (Washington County),[3] and can be seen a short distance east of Las Vegas, Nevada.[2]

Habit, Lake Mead National Recreation Area

Enceliopsis argophylla
In Lake Mead National Recreation Area, Nevada
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Asterids
Order:
Asterales
Family:
Asteraceae
Tribe:
Heliantheae
Genus:
Enceliopsis
Species:
E. argophylla
Binomial name
Enceliopsis argophylla
Synonyms[1]
  • Encelia argophylla (D.C.Eaton) A.Gray
  • Helianthella argophylla (D.C.Eaton) A.Gray
  • Tithonia argophylla D.C.Eaton

Description

E. argophylla is a perennial herb up to 80 cm (2.6 ft) tall, appearing silvery because of many small hairs pressed against the leaves. Leaf blades are up to 10 cm (3.9 in) long, with wings running along the sides of the petioles. Appearing in April and May, the flower heads are yellow, at the ends of long peduncles, each head with as many as 35 ray florets and up to 500 tiny disc florets. The achene is strongly flattened, covered with small hairs, and sometimes with a pappus of 2 awns up to 2 mm long (unlike some of the related species).[4][5][6]

American botanist Daniel Cady Eaton described the silverleaf sunray as Tithonia argophylla in 1871.[5]

Location

Found in Clark and Mohave Counties in the vicinity of the artificial reservoir Lake Mead,[2] it grows on stony barren slopes at 1,000 to 1,500 m (3,300 to 4,900 ft) altitude.[4] It often grows alongside the rare golden bear-claw poppy or Las Vegas bear-poppy Arctomecon californica. Both plants grow in a fragile gypsum crust on the soil, which when damaged facilitates the spread of invasive plants. Its habitat is threatened by the reservoir as well as off-road recreational vehicle use.[2]

References
  1. The Plant List, Enceliopsis argophylla (D.C.Eaton) A. Nelson
  2. Still, Shannon; Jensen, Nick (20 February 2013). "My Chicago Botanical Garden, A Rare Plant Portrait: The Silverleaf Sunray (Enceliopsis argophylla)". My Chicago Botanic Garden. Chicago Botanic Garden. Retrieved 22 June 2015. photos plus info on ecology and conservation
  3. "County distribution map". Biota of North America Program. 2014. Retrieved 22 June 2015.
  4. "Enceliopsis argophylla (D. C. Eaton) A. Nelson". Flora of North America. Retrieved 22 June 2015.
  5. Eaton, Daniel Cady (1871). Watson, Sereno (ed.). Botany. United States Geological Exploration [sic] of the Fortieth Parallel. Vol. 5. p. 423.
  6. Sanders, D. L. and C. Clark. 1987. Comparative morphology of the capitulum of Enceliopsis. American Journal of Botany 74: 1072–1086.
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