Banner Dudleya [Dudleya alainae Reiser]

Banner Dudleya [Dudleya alainae Reiser]

Listing CNPS List 3 R-E-D Code 3-2-3

State/Federal. Status -- None CRASSULACEAE Jun.-Jul.

Global Rank G1Q State Rank S1?

Distribution: San Diego County

Habitat: Lower Montane Coniferous Forest and Chaparral ecotone are the preferred habitat of the Banner Dudleya. This succulent perennial favors exposed rocky outcrops where it can utilize cracks and crevices with only limited soils, and is pressured by only minimal competition from other plants. Soils are mapped as Crouch coarse sandy loam near Harrison Park, Sheephead rocky fine sandy loam in Banner, and Holland stony fine sandy loam both near Jim Green Creek and at Pine Hills. The Banner Dudleya appears more closely correlated with metamorphic, exposed rock and with sufficient winter rainfall, than with specific soil type.

Known Sites: This Dudleya is uncommon in Banner and Chariot Canyon. A large population occurs adjacent to Jim Green Creek at the foot of the Volcan Mountains in open rocky terrain. It is scattered in rocks south of the American Adventure Campground near Harrison Park. It is localized in rocks at Pine Hills near the intersection of Eagle Peak Road and Blue Jay Drive. A small population of dudleya on French Creek growing in shaded coniferous forest in the Palomar Mountains is apparently this species.

Status: Banner Dudleya populations in the mountains of San Diego County are presently stable. It is potentially impacted by construction of mountain cabins, recreational campgrounds, and by the overgrazing of horses and cattle. CNPS List 1B is recommended for this species. Substantial portions of all populations should be protected. This succulent perennial is sometimes referred to Dudleya saxosa ssp. aloides. However, Dudleya saxosa ssp. aloides typically occurs in desert mountains (e.g., Sentenac Canyon, Dry Morongo Wash, the foothills of the Santa Rosa Mountains just west of Palm Desert, Aguanga) which share almost no floristic species with the coniferous forest and montane chaparral habitat of the Banner Dudleya. Almost all other dudleya species in California have very restrictive habitat requirements; even the wide ranging Dudleya pulverulenta has a desert subspecies arizonica to separate it from the more coastal subspecies pulverulenta. The greenish-yellow flowers, generally taller and typically reddish peduncle with a substantially more open inflorescence, as well as the quite different, barren, rocky, desert terrain with few shrubs and much higher seasonal temperatures, separate D. saxosa from the diminutive D. alainae with sulphur yellow flowers found within or near montane, Jeffrey Pine habitat. A complex of dudleya forms in the foothills of the eastern Transverse Range and northern Peninsular Range needs further study. Plants at different sites show differing mixes of characteristics of Dudleya lanceolata, Dudleya cymosa, Dudleya saxosa and possibly Dudleya alainae; some of these were formerly referred to Dudleya cymosa ssp. minor. Uncommon caespitose plants in the Vulcan, Cuyamaca, Laguna, and Jacumba Mountains with pale yellow-green or whitish-green flowers with a red-striped keel and very short peduncles are Dudleya abramsii ssp. abramsii (= Dudleya delicata).

Copyright May 1994 Craig H. Reiser.

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