Dudleya blochmaniae subsp. brevifolia

Dudleya blochmaniae subsp. brevifolia
Short-Leaved Dudleya at Carmel Mountain, San Diego
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Core eudicots
Order:	Saxifragales
Family:	Crassulaceae
Genus:	Dudleya
Species:	D. blochmaniae
Subspecies:	D. blochmaniae subsp. brevifolia
Trinomial name
Dudleya blochmaniae subsp. brevifolia Moran

Dudleya blochmaniae subsp. brevifolia is a succulent plant known by the common name Short-leaved Liveforever or Short-leaved Dudleya. This plant is a rare subspecies of Dudleya blochmaniae with an extremely limited and endemic range in San Diego County, California.

Description

It grows into a somewhat erect, small (1–4 cm), cryptic, and corm-like succulent perennial with cone-shaped leaves along its hidden stem. It may be brown, reddish-purple, or greenish and bears a branching inflorescence with a few flowers per branch, each opening into a star-shaped bloom with five pointed petals. It sprouts after significant winter rains (December to February) and flowers from May to June. It produces a many-seeded fruit from a simple pistil, which disperses seeds along a single suture. It is only found on bare surface hardpans of Torrey sandstone with minimal topsoil. Small marble-sized, iron-bearing granules are present at all sites and are likely an edaphic requirement.

Total population estimates vary by year and by researcher. Extensive studies have been completed on Carmel Mountain, Carmel Valley, San Diego. The Multiple Species Conservation Program (MSCP) of San Diego County estimated the Carmel Mountain population at just 1446 individuals in 2002, and at 113,134 individuals in 2006. Most recently, in 2008, UCLA faculty Dr. Hartmut S. Walter and Matthew Luskin estimated the Carmel Mountain population at over 100,000 individuals. Their population is highly dependent on rainfall, exploding in population when there is annual rainfall over 10 inches, and drastically shrinking when there is less than 4 inches of annual rainfall.

Conservation

Dudleya blochmaniae subsp. brevifolia is a high conservation priority because it exists only in these 5 locations (listed by decreasing average yearly population): Torrey Pines State Reserve, Carmel Mountain (on multiple sites), Crest Canyon, Skeletal Canyon, and Torrey Pines Extension. The total habitat outside of the Torrey Pines State Reserve that contains this species was estimated at just 2,667 square meters.

Dudleya blochmaniae subsp. brevifolia is listed as an endangered species in California (listed January 1982). On October 7, 1996, the U.S. Fish and Wildlife Service withdrew federal protection as an endangered species citing the threats to the species had diminished and that it was a "covered species" within the Multiple Species Conservation Program (MSCP) of southern San Diego County.

References

• http://pubs.usgs.gov/sir/2007/5016/
• http://www.fws.gov/Endangered/pdfs/FR/p961007.pdf
• http://www.dfg.ca.gov/habcon/cgi-bin/read_one.asp?specy=plants&idNum=91
• California Native Plant Society. 2001. Inventory of Rare and Endangered Plants of California. (database) Rare Plant Scientific Advisory Committee, California Native Plant Society. Sacramento, CA. Data tables from electronic copy of the Inventory.
• http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Dudleya+blochmaniae+ssp.+brevifolia
• http://plants.usda.gov/java/profile?symbol=DUBLB2
• http://www.sandiego.gov/planning/mscp/pdf/monitor/dudleyabre2003.pdf
• Hickman, J. C. (editor) 1993. The Jepson manual: higher plants of California. Berkeley, CA. University of California Press.