Localities documented in Tropicos sources
United States (North America)
Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Restricted to the zone of coastal influence in southern California and northern Baja California, Mexico.
Leaves generally < 12 per rosette; peduncle > 4 cm; mainland (Hickman 1993).
Comments: Coastal sage scrub, chaparral, coastal bluff scrub and valley and foothill grassland below 450 meters and within the immediate influence of the coast. Seems to thrive in open, rocky slopes, often serpentine and ultramafic clay soils, though sand and loam are also known to support populations (Hickman 1993).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 21 - 80
Comments: Fewer than 20 Element Occurrences in California and 5 in Baja California, Mexico.
Rodents are known to eat these plants. Rabbits sometimes burrow after the corms. This taxon is drought tolerant, and seems to tolerate some disturbance, though decreased competition may be the true reason the plants seem to tolerate disturbance. Avena competes in clay soils.
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: T2 - Imperiled
Reasons: Dudleya blochmaniae ssp. blochmaniae is known from fewer than twenty extant occurrences in southern California and fewer than five extant occurrences in Baja California, Mexico. Development seriously threatens this taxon.
Global Short Term Trend: Decline of 10-30%
Comments: Development in southern California is destroying the habitat for this species.
Comments: Development is threatening this species.
Needs: Some occurrences must be protected by habitat acquisition.
Restoration Potential: The potential for restoration of this species is very good if suitable habitat can be protected. Plants will grow from cuttings and often flower in their first year. Wild populations could easily be augmented with this practice.
Preserve Selection and Design Considerations: Plants need open, rocky slopes within the zone of coastal influence and serpentine or clay soils. Sites for preserves should have a viable mosaic of coastal scrub, chaparral, coastal bluff scrub and grassland with open, rocky patches. Both northern and southern populations should be preserved as they are genetically distinct.
Management Requirements: Plants are hardy and will tolerate some disturbance. Trampling and land conversion are the main things to avoid. Keep propagules from northern and southern populations separate; they are genetically distinct.
Management Programs: Some southern California populations are being managed (e.g., Camp Pendleton), but most populations are left unprotected.
Relevance to Humans and Ecosystems
Stewardship Overview: Some of the southern California populations are being managed. Most populations are unprotected and threatened by development.
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