Dudleya saxosa subsp. aloides

Dudleya saxosa subsp. aloides is a species of perennial succulent plant in the family Crassulaceae known by the common names desert dudleya or desert savior. It is a rosette-forming species widely distributed throughout the Peninsular Ranges and desert mountains of California in the United States. It is characterized by bright-yellow or greenish-yellow flowers, and can be found in shaded crevices and slopes. Plants in western half of the range may grade into Dudleya lanceolata.

Desert dudleya

Vulnerable  (NatureServe)[1]
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Saxifragales
Family: Crassulaceae
Genus: Dudleya
Species:
D. saxosa
Subspecies:
D. s. subsp. aloides
Trinomial name
Dudleya saxosa subsp. aloides
(Rose) Moran
Synonyms
  • Dudleya aloides Rose
  • Dudleya delicata Rose
  • Dudleya grandiflora Rose
  • Dudleya lanceolata var. aloides (Rose) Munz
  • Dudleya lanceolata var. composta Jeps.

Description

A rosette-forming succulent that may be evergreen or summer deciduous. It typically has bright yellow or green flowers.[2]

This plant's basal rosette is formed on top of a caudex (stem), which is 1 to 3 cm in diameter. There are 1 to 4 rosettes, and they may be 6 to 23 cm wide. The leaves are typically 4 to 15 cm long, and 6 to 25 mm wide, 2 to 5 mm thick, and their base is 10 to 25 mm wide.[3][4]

Growing in Joshua Tree National Park

The inflorescence has a peduncle 10 to 51 cm tall, and 1 to 9 mm wide. The lower internodes are spaced over 5 mm. The peduncle then branches 3 times, with the floral shoots colored red or green. The terminal branches (cincinni) are wavy, 1 to 12 cm long, and have 2 to 20 flowers. The sepals are around 4 to 6 mm long. The petals are 8 to 15 mm long, and are fused 1.5 to 3 mm. The petals are colored bright yellow or green, but rarely they are tinged with red. Flowering is from April to June[3][4]

Taxonomy

Taxonomic history

This species was described as Dudleya aloides in 1903, based on a specimen collected from San Diego County by Townshend Brandegee and examined by Nathaniel Lord Britton and Joseph Nelson Rose during their revision of North American Crassulaceae species. The two also described Dudleya grandiflora, from Whitewater near Banning, California, also collected by Brandegee. A third taxon, the comparatively diminutive Dudleya delicata, was also described by Britton and Rose, collected by LeRoy Abrams near Julian.[5]

W.L. Jepson placed the species as Echeveria lanceolata var. composta.[6] Reid Moran placed it as Dudleya lanceolata ssp. aloides in 1951. Moran eventually combined Dudleya aloides as a subspecies of Dudleya saxosa, forming the current combination in 1957.[7] Dudleya grandiflora was recognized as synonymous with subspecies aloides, although the plants called grandiflora are slightly larger than typical subsp. aloides.[4]

Dudleya alainae

In 1984, botanist Craig H. Reiser recognized a number of Dudleya occurring on the eastern side of the Cuyamaca Mountains as Dudleya alainae, commonly known as the Banner dudleya. He recognized them as distinct based on diagnostic criteria that included sulphur-yellow flowers, (as opposed to bright yellow or greenish-yellow) a smaller inflorescence, and restricted montane habitat compared to subsp. aloides.[8]

In 1986, another botanist, Kei M. Nakai, recognized Dudleya alainae as being synonymous with Rose's Dudleya delicata species, and therefore a synonym of Dudleya saxosa subspecies aloides. The group of plants variously referred to as Dudleya alainae or delicata approach the lowland Dudleya lanceolata. The chromosome number is n = 17.[4] The treatment by botanist Stephen W. McCabe in the Jepson Manual regards Dudleya alainae as "in need of study."[3]

Phylogeny

Dudleya saxosa subsp. aloides has a chromosome number of n = 17. Despite its placement in the species Dudleya saxosa, the other members, subsp. collomiae (n = 68) and subsp. saxosa ( n = 68, n = 85),[9] are disjunct (geographically isolated) in distribution and polyploid. However, it also does not fit in with Dudleya lanceolata ( n = 34 ), as that species is tetraploid.[4]

Distribution and habitat

This species is found primarily in the Peninsular Ranges and on desert mountains in the Mojave and Sonoran deserts in California, USA. It does not likely occur in Mexico. Plants in the northernmost section of the distribution tend to be smaller, while plants near the type locality of Dudleya grandiflora, near Banning, are larger. Plants in western portion of the distribution in the Peninsular Ranges approach Dudleya lanceolata, and hybrids are expected. This species is found growing in rocky, shaded slopes and crevices.[4][3]

References
  1. "NatureServe Explorer 2.0".
  2. "Dudleya saxosa ssp. aloides". San Marcos Growers. Archived from the original on 2012-09-22. Retrieved 29 December 2021.
  3. McCabe, Stephen W. (2012). "Dudleya saxosa subsp. aloides". Jepson eFlora. Jepson Flora Project. Archived from the original on 2015-12-20. Retrieved 29 December 2021.
  4. Moran, Reid V. "Dudleya saxosa subsp. aloides". Flora of North America. 8: 187 – via efloras.org.
  5. Rose, Joseph Nelson (1903). "New or noteworthy North American Crassulaceae". Bulletin of the New York Botanical Garden. 3 (9): 15, 16, 24.
  6. Jepson, Willis Linn (1936). Flora of California 2. p. 115.
  7. Moran, Reid V. (1957). "Innovations In Dudleya". Madroño. 14 (3): 108.
  8. Reiser, Craig (1984). "Dudleya Alainae, A New Species from San Diego County". Cactus & Succulent Journal of America. Cactus & Succulent Society of America. 1984 Jul-Aug: 147–148.
  9. Moran, Reid; Uhl, Charles H. "The Cytotaxonomy of Dudleya and Hasseanthus". American Journal of Botany. 40.
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