Pink sand-verbena (Abronia umbellata) COSEWIC assessment and status report: chapter 11

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Technical Summary

Abronia umbellata

Pink sand-verbena – abronie rose

Extent and Area Information

Population Information

Threats (actual or imminent threats to populations or habitats)

• introduced species competition; 
• decimation by winter storms;
• trampling by hikers

Rescue Effect (immigration from an outside source)

Quantitative Analysis

Not Applicable

Current Status

Status and Reasons for Designation

Alpha-numeric code:  B1ab(ii,iii)+2ab(ii,iii); C2a(i,ii); D1

Reasons for Designation: An herb of maritime beach habitats last seen at a single site along the west coast of Vancouver Island with losses of two historic populations. The site of the last documented population is greatly disjunct from other small populations in Oregon. The species is found, characteristically, in low numbers and tends to persist in the seed-bed of its beach and foredune habitats, sporadically producing flowering plants.  The species was last recorded in 2001 with only several plants present. It is assumed that the species may still persist as dormant seeds and may produce reproductive plants at some future date. The expansion of exotic beach grasses has reduced the quality and availability of its upper beach and foredune habitats at a number of sites within its historic range.

Applicability of Criteria

Criterion A (Declining Total Population): Applicability of this criterion in relation to reduction in population size is uncertain in view of the fragmentary and relatively recent population data and the small numbers of plants present and the inherent characteristic of fluctuating population size associated with this perennial species.

Criterion B (Small Distribution, and Decline or Fluctuation): Endangered under B1 and B2 (a) plus (b, ii, iii) due to small historic EO of < 100 km² and area of occupancy of << 20 km² and only 1 recent site with very few plants; most recently, no plants were found at the single site. Criterion B1 and B2 (b) applies due to the inferred loss of area of occupancy and extent or quality of habitat due to the major invasion of suitable beach habitats by exotic grasses.

Criterion C (Small Total Population Size and Decline): Endangered under C2(a i, ii) due to population fragmentation with no population >250 plants and 95% of mature individuals in one population.

Criterion D(Very Small Population or Restricted Distribution):Endangered under D1 due to the potential production of a small number of plants from the seed bed in the beach sands; characteristically this species only produces a very few plants in a sporadic fashion which in all likelihood would total <250 plants.

Criterion E (Quantitative Analysis): Not Applicable