Dudleya saxosa subsp. collomiae

Dudleya saxosa subsp. collomiae, known by the common name Gila County liveforever, is a subspecies of perennial succulent plant within the genus Dudleya native to central Arizona. It is characterized by showy bright-yellow flowers on an upright inflorescence colored pink, red or orange. The leaves are green or covered in a white, powdery wax. This species is found growing in rocky slopes, canyons, and crevices, and often on Sonoran Desert sky islands.[3]

Dudleya saxosa subsp. collomiae

Apparently Secure  (NatureServe)[1]
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Saxifragales
Family: Crassulaceae
Genus: Dudleya
Species:
D. saxosa
Subspecies:
D. s. subsp. collomiae
Trinomial name
Dudleya saxosa subsp. collomiae
Synonyms[2]
  • Dudleya collomiae Rose
  • Echeveria collomae (Rose) Kearney & Peebles

Morphology
Flowering

This species has a caudex (stem) 1.5–3 cm (0.59–1.18 in) in diameter. Topping the stem is a rosette of leaves, which may be colored green or covered in a white, powdery epicuticular wax. The leaf blades are 5–15 cm (2.0–5.9 in) long by 1–2.5 cm (0.39–0.98 in) wide, and 2–6 cm (0.79–2.36 in) thick. [4]

The inflorescence is composed of red floral shoots, covered in 5 to 12 bracts. The terminal branches are 3–12 cm (1.2–4.7 in) long and bear 4 to 15 flowers on pedicels 5–20 mm (0.20–0.79 in) long. The flowers have their parts in 5. The sepals are 4–7 mm (0.16–0.28 in) long, while the petals are 12–16 mm (0.47–0.63 in) long. The petals are bright yellow but tinged with red.[4][5]

Taxonomy

Dudleya saxosa subsp. collomiae has been variously classified as a separate species, or a member of the genus Echeveria, like many Dudleya, but current consensus has it as a subspecies of Dudleya saxosa.

Etymology

The species is named for Mrs. Rose E. Collom, a botanist, of which she collected the holotype specimen of Dudleya saxosa subsp. collomiae.[6]

Phylogenetics

This species has a chromosome number of n = 68. Compared to a similar relative under the same species, Dudleya saxosa subsp. aloides, a diploid, the Arizona subspecies is polyploid, and has larger flowers. They are also relatively isolated from each other, with the whole species having a disjunct distribution.[7][4]

Distribution and habitat

Dudleya saxosa subsp. collomiae is the only other species of Dudleya native to Arizona, the other being Dudleya arizonica, the Arizona Chalk Dudleya. It has a preference for rocky slopes, crevices, and canyons in central Arizona on sky islands, occurring from 2,000 to over 6,000 ft. in elevation.[5]

References
  1. "Dudleya saxosa ssp. collomiae". NatureServe Explorer [web application]. Arlington, Virginia: NatureServe. 2022. Retrieved 8 April 2022.
  2. "Dudleya saxosa subsp. collomiae". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 8 April 2022.
  3. "Dudleya collomiae saxosa, Gila County Live-forever, Southwest Desert Flora". southwestdesertflora.com. Southwest Desert Flora. 2017. Retrieved 8 April 2022.
  4. "Dudleya saxosa subsp. collomiae". Flora of North America. 8: 187–188 – via efloras.org.
  5. Thomson, Paul H. (1993). Dudleya and Hasseanthus Handbook. Bonsall, California: Bonsall Publications. pp. 64–65. ISBN 9780960206650.
  6. Gentry, Mary A. (1082). "Women Botanists and Plant Collectors of Arizona" (PDF). Central Arizona Cactus and Succulent Society Newsletter, the Central Spine. 2 (4): 2. Retrieved 26 March 2015.
  7. Moran, Reid (1957). "Dudleya saxosa (M. E. Jones) Britton & Rose subsp. collomiae". Madroño. 14: 108.
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