There are a number of characteristics which can be summarized regarding the Dudleya genus. Genus occurrences are restricted to southwest North America; in fact, according to Low, approximately 98 percent of genus occurrences are along or near the coasts of Baja California, (the states of Baja Sur and Baja Norte in Mexico), plus the northward extension into the USA in the states of California and southern Oregon. A small number of genus populations are found in Arizona and possibly Nevada. The center of genus diversity is the coastal region where Mexico and the USA meet. Dudleyas have a strong affinity for the coastal regions, but some species have ranges that extend into the nearby mountains and deserts.
Most species of Dudleya grow at elevations near sea level, but a few grow on or even atop mountains of Baja California, the high Sierra Nevada and in many other California mountain ranges. Many, such as D.cymosa, prefer canyon locations on vertical or near vertical rocky walls, often in the shade, surviving in very little soil in the crevices of almost solid rock. Sometimes the occurrences are in locations that receive no direct sunlight. Almost all Dudleya species have succulent leaves arranged into rosettes. Because of this rosette geometry many genus members are striking in their visual appeal. Many, including the Canyon Liveforever, have leaves that are glaucous (covered with a whitish or bluish waxy coating) or frosty looking.
The chromosome count of all Dudleya species is n=17, with about 35% of all populations consisting of polyploids (individuals with multiples of the base number). Remarkably, according to extensive crossing experiments conducted by Verity, all Dudleya taxa are capable of hybridizing in nature.
There are eight recognized subspecies of D. cymosa (flower color in parentheses):
- D. cymosa subsp. agourensis K.M.Nakai: Canyon Liveforever (bright yellow)
- D. cymosa subsp. crebrifolia K.M.Nakai & Verity: San Gabriel River dudleya (mustard yellow)
- D. cymosa subsp. costafolia Bartel & Shevock: Pierpoint Springs Dudleya (bright yellow)
- D. cymosa subsp. cymosa: Canyon Liveforever, the nominate subspecies (bright yellow, red or orange)
- D. cymosa subsp marcescens Moran: Marescent Dudleya (bright yellow with orange or red markings)
- D. cymosa subsp ovatifolia: (Britton) Moran Santa Monica Mountains Dudleya (bright yellow, rarely with red or orange marking)
- D. cymosa subsp. paniculata: (Jeps.) K.M.Nakai (pale yellow-white to pale yellow-pink)
- D. cymosa subsp. pumila: (Rose) K.M.Nakai (bright yellow or red)
- C. Michael Hogan. 2011. ''Dudleya cymosa (Lem.) Britt. & Rose. Encyclopedia of Earth, National Council for Science and the Environment, Washington DC eds. A. Howald & M. McGinley
Molecular Biology and Genetics
Statistics of barcoding coverage
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Many plants in the Dudleya genus were formerly classified as Echeveria.
The fleshy and glabrous leaves occur in basal rosettes, in colors generally ranging from green to gray. The inflorescences are on vertical or inclined stems up to a meter high, but usually much shorter, topped by a cyme with alternate leaf-like bracts. Both the petals and sepals of the small flowers are five in number and fused below. Five pistils, also fused below, have 10 stamens arranged around them.
Dudleya species are widespread in their range, typically found in rock outcroppings, cliff faces, or road cuts, where their leaves help them store water in a setting too dry for most types of plants. Most are small and inconspicuous when not in bloom.
In horticulture, Dudleya should be planted at an angle. This allows accumulated water to drain from the nestlike center of the plant, thus preventing microbial decay.
- Dudleya abramsii
- Dudleya anthonyi - formerly in Echeveria
- Dudleya attenuata - Orcutt's live-forever, Tapertip live-forever. Formerly in Echeveria, sometimes included in D. edulis
- Dudleya blochmaniae
- Dudleya blochmaniae ssp. brevifolia
- Dudleya brittonii
- Dudleya caespitosa - Sea Lettuce. Syn. Echeveria californica, E. cotyledon, E. helleri, E. laxa, Sedum cotyledon.
- Dudleya calcicola - Limestone dudleya
- Dudleya candelabrum
- Dudleya candida - formerly in Echeveria
- Dudleya crassifolia
- Dudleya cultrata - formerly in Echeveria
- Dudleya cymosa - Canyon live-forever. Formerly in Echeveria.
- Dudleya densiflora
- Dudleya edulis - Fingertips. Formerly in Echeveria or Sedum.
- Dudleya farinosa
- Dudleya gnoma - Munchkin dudleya
- Dudleya greenei
- Dudleya guadalupensis
- Dudleya hassei - Catalina live-forever, Catalina dudleya
- Dudleya ingens
- Dudleya lanceolata
- Dudleya linearis
- Dudleya multicaulis - Many-stemmed dudleya
- Dudleya nesiotica
- Dudleya pachyphytum - Cedros Island dudleya
- Dudleya palmeri
- Dudleya pulverulenta - Chalk lettuce. Syn. Echeveria argentea, E. pulverulenta, Cotyledon pulverulenta
- Dudleya saxosa - Rock live-forever. Syn. Echeveria collomiae
- Dudleya setchellii - Santa Clara Valley dudleya
- Dudleya stolonifera
- Dudleya traskiae - Santa Barbara Island live-forever
- Dudleya variegata
- Dudleya verityi
- Dudleya virens - Alabaster plant, Island live-forever
- Dudleya viscida - Sticky Dudleya
- Dodero, M. W. and M. G. Simpson. (2012). Dudleya crassifolia (Crassulaceae), a new species from northern Baja California, Mexico. Madroño 59(4) 223-229.
- Thompson, P. Dudleya and Hassenthaus Handbook. Bonsall Publications. 1993. ISBN 0-9602066-5-5 ISBN 9780960206650
- Treatment from the Jepson Manual
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