Dudleya

Dudleya
Short-leaved dudleya (Dudleya brevifolia) at Carmel Mountain, San Diego
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Saxifragales
Family:	Crassulaceae
Subfamily:	Sempervivoideae
Tribe:
Genus:	Dudleya Britton & Rose
Species
Numerous, see text

Dudleya cymosa, Tilden Regional Park near Berkeley, CA.

Dudleya is a genus of succulent perennial plants, consisting of about 46 species with around 68 taxa in southwestern North America. Dudleya are fleshy, glabrous plants, sometimes farinose, with leaves that are typically organized into rosettes. The flowers of Dudleya typically have petals and sepals numbered in 5, and when fruiting are filled with tiny, ovoid or crescent-shaped seeds. Some species are cultivated as ornamental plants, and others are threatened by poaching.^[1]

Description[]

The fleshy and glabrous leaves occur in rosettes, in colors generally ranging from green to gray, with some species having their foliage covered in an epicuticular wax, or farina.^[1]The farina is mostly composed of pentacyclic triterpenoids.^[2] Other members, such as D. viscida and D. anomala, have a viscid, adhesive layer on their foliage. 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.

Etymology[]

The genus is named after William Russell Dudley, the first head of the botany department at Stanford University. Members of the genus are commonly referred to as liveforevers.^[1]

Taxonomy[]

Many plants in the Dudleya genus were formerly classified as Echeveria.

Taxonomic classification of Dudleya taxa remains problematic, as members of the genus freely hybridize with each other and often occur in difficult locations for observation.

Selected species[]

Munchkin dudleya
Dudleya gnoma

Distribution and habitat[]

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.

Dudleya can be found in The Californias, Arizona, Sonora, Oregon and southern Utah and Nevada. A large portion of Dudleya taxa exist in coastal regions, although some can be found over vast swathes of the interior of Southwestern North America.^[20]

Species existing in the Baja California peninsula, particularly D. rigida, D. pauciflora and D. nubigena, occur in high altitude, montane regions. ^[17]

Cultivation[]

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 should not be watered from directly above, as this may damage their chalky coating known as farina, which is present on numerous species. Mealybugs and aphids are main pests of Dudleya.^[21][22] Powdery mildew has also been recorded in cultivated Dudleya.^[23]

Propagation[]

Unlike their related genera Echeveria, Dudleya cannot be propagated through leaf cuttings. Propagation can only be achieved via offsets or germination by seed. Dudleya seeds are crescent shaped and near-microscopic, and can be collected by taking the dried flower buds and crushing the ovules inside, which can contain hundreds of seeds. Seeds can be sown into a soilless medium, such as pumice or vermiculite, after which germination can occur within a week to 10 days.^[24]

Conservation[]

Several species of Dudleya are threatened by urban development in Coastal California and Mexico, and anthropogenic-induced wildfires. However, one of the most critical threats to Dudleya species is poaching, partially caused by a demand from East Asian succulent collectors paying lucrative prices for certain Dudleya species.^[25]

The population of Verity's live-forever, which was nearly wiped out during the 2013 Springs Fire, was targeted by poachers.^[26][27]

The Cedros Island Dudleya, D. pachyphytum, a rare and extremely specialized Dudleya endemic to Cedros Island, was nearly extirpated after Mexican soldiers stopped poachers from taking nearly 5,000 rosettes in a tractor-trailer. It was suspected the poachers rappelled onto the succulent's location via helicopter, as D.pachyphytum occupies a nearly inaccessible habitat. In 2019, the deaths and injuries of several fishermen from Bahía Tortugas on Cedros Island was allegedly the result of Dudleya trafficking, a conflict with the Sinaloa Cartel, or both. In 2020, the Mexican Navy in the Second Naval Region reported that two fishermen were killed after a dispute emerged over the trafficking of the rare plant.^{[28][29][30][31][32]}

Bluff lettuce (D. farinosa) was also targeted by poachers in numerous large-scale operations. Although not particularly rare, the size of the poaching operation pose a serious ecological threat. Starting in 2017, the U.S. Customs and Border Protection, along with the California Department of Fish and Wildlife, discovered large amounts of D. farinosa being shipped out of the country. South Korean and Chinese nationals have both been arrested in the smuggling of D. farinosa. According to nursery owners responsible for legally exporting Dudleya, buyers in Asia desired plants directly from the wild, owing to the aesthetic quality of their long caudices and weathered leaves.^[33][34]

In response to the poaching of Dudleya, California State Assembly member Chris Ward proposed Bill AB-223, which would make it illegal to poach Dudleya.^[35]The California Native Plant Society and conservationists have also initiated propagation programs to oversaturate the market as a means to deter poachers.^[24][36]

References[]

Further reading[]

• 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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