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BC Conservation Data Centre: Species Summary

Sabulina pusilla
dwarf sandwort

Scientific Name: Sabulina pusilla (S. Watson) Dillenberger & Kadereit
Scientific Name Synonyms: Arenaria pusilla
Minuartia pusilla
English Name: dwarf sandwort
Classification / Taxonomy
Scientific Name - Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Classification Level: Species
Species Group: Vascular Plant
Species Code: SABUPUS
Kingdom Phylum Class Order Family
Plantae Anthophyta Dicotyledoneae Caryophyllales Caryophyllaceae
Conservation Status / Legal Designation
Global Status: G3G5 (Jun 2004)
Provincial Status: S1 (Apr 2019)
BC List: Red
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status: Endangered (May 2004)
SARA Schedule: 1  -  Endangered (Jul 2005)
General Status Canada: 1 - At Risk (2010)
Ecology & Life History
General Description:
Technical Description:
Identification Comments: Annual herb from a weak taproot, with a whitish or grayish-blue (glaucous) tinge. Stems erect, solitary or more often several, simple to branched, glabrous and more or less glaucous, 2-5 cm tall. Basal and lower stem leaves opposite, linear, 2-4 mm long, less than 0.5 mm wide, glabrous, obtuse, 1-nerved. Upper stem leaves few, similar, not much reduced, with stipules lacking. Inflorescence usually of several flowers in an open, leafy-bracted cluster that is often 4/5 the total height of the plant. Petals elliptic, entire, 1-2 mm long but sometimes lacking. Sepals lanceolate, long-pointed or abruptly sharp-pointed, 2-3 mm long, 3-nerved. Capsules egg-shaped, 1-2 mm long, 3-valved. Seeds brown, about 0.3 mm long, minutely pimply (COSEWIC 2004j; Parks Canada Agency 2006).
Similar Species: Stellaria nitens is similar but has cleft petals. Sagina decumbens ssp. occidentalis has rounded sepals. Minuartia tenella has glandular-hairy sepals and stems. All species occur in the same type of habitat as M. pusilla (COSEWIC 2004j).
Provincial Reproduction Comments: No information on reproduction specific to Minuartia pusilla is available, but it is thought to be similar to related taxa. Baskin and Baskin (1987) found that dormant seeds in Arenaria fontinalis required high summer temperatures to promote after-ripening that released seeds from dormancy in the fall. Meinke and Zika (1992) report that M. pusilla has tiny flowers that lack nectar glands and occasionally lack petals. Because its anthers open prior to floral expansion, M. pusilla appears to be exclusively self-pollinating. Pollinators have not been observed on M. pusilla in BC. Seeds of M. pusilla have no mechanisms for dispersal, but may be disseminated by shorebirds. Rocky Point is adjacent to the ocean and gulls are known to frequent the area (COSEWIC 2004j; Parks Canada Agency 2006).
Provincial Ecology Comments: Little information is available for the ecology of Minuartia pusilla. It is an ephemeral species and relies on seasonal precipitation for germination and longevity (Meinke and Zika, 1992). It requires open conditions with limited competition from other vegetation. It likely experiences demographic fluctuations as a result of natural but irregular and limited winter rains. It is possible that the species could disappear altogether if critical moisture is not available for germination and seedling development, and is therefore potentially susceptible to climate change. Recorded population size has ranged from as few as nine to several hundred individuals. Random fluctuations in demographic performance could be sufficient to drive this population to extinction (COSEWIC 2004j; Parks Canada Agency 2006).
(Type / Subtype / Dependence)
Forest / Conifer Forest - Dry / Facultative - frequent use
Grassland/Shrub / Grassland / Facultative - occasional use
Grassland/Shrub / Meadow / Facultative - frequent use
Other Unique Habitats / Garry Oak Vernal Pool / Facultative - frequent use
Other Unique Habitats / Vernal Pools/Seasonal Seeps / Facultative - frequent use
Provincial Habitat Comments: In BC, the only known habitat of Minuartia pusilla at Rocky Point is a shallow depression in a sloping, vernal seepage area on a rocky maritime headland. Vernal seeps are shallow flows that occur where groundwater emerges on sloping terrain, usually on the lower slopes of hillsides, and they tend to dry up by late spring or early summer. The southeast sloping (0-24%) depression is wet in the spring and mesic to dry later in the season. The substrate consists of shallow (3-7 cm deep) organic mineral soil with no pronounced structure, overlying bedrock. Soils are a rapidly draining sandy moder with poor nutrient content and no soil moisture late in the season. The root-restricting layer is 1-20 cm and the coarse fragment content is about 35-70%. The soil is saturated during the winter and remains damp through the spring, but dries completely by early summer, traits that help suppress encroachment of competing herbaceous or woody species. The vegetation of the coastal headlands where M. pusilla occurs is controlled by exposure to winds and salt spray. Associated species include Aira praecox, Agrostis microphylla, Allium amplectens, Armeria maritima, Bryum miniatum, Cerastium glomeratum, Crassula connata, Dodecatheon pulchellum, Gnaphalium spp., Hypochaeris radicata, Mimulus guttatus, Montia fontana, Orthocarpus pusillus, Plagiobothrys scouleri, Plantago elongata, Plantago lanceolata, Poa confinis, Triphysaria pusilla, Vulpia myuros, and Vulpia bromioides. Nearby rare species include Callitriche marginata, Lotus formosissimus, and Sanicula arctopoides. Erosion plays a key role in maintaining a constant, fresh supply of mineral soil that is needed for germination by M. pusilla (COSEWIC 2004j; Parks Canada Agency 2006).
Provincial Phenology:
(1st half of month/
2nd half of month)
Jan: Vegetative, Germinating / Vegetative, Germinating
Feb: Vegetative / Vegetative
Mar: Vegetative / Vegetative
Apr: Vegetative / Vegetative
May: Vegetative, Flowering / Vegetative, Flowering, Fruiting
Jun: Flowering, Fruiting / Flowering, Fruiting
Jul: Vegetative / Vegetative
Aug: Vegetative / Vegetative
Sep: Vegetative / Vegetative
Oct: Vegetative / Vegetative
Nov: Vegetative / Vegetative
Dec: Vegetative, Germinating / Vegetative, Germinating
Provincial Phenology Comments: In BC, Minuartia pusilla likely germinates in December or January and reaches reproductive age within one year. It potentially overwinters in the seedling stage and therefore behaves as a winter annual with flowers developing in May or June. Meinke and Zika (1992) reported M. pusilla to be a strict ephemeral that is reliant on precipitation both before and during the growing season for germination and longevity. Ongoing studies of phenological patterns in M. pusilla are currently being conducted by M. Fairbarns (Fairbarns 2005h; Parks Canada Agency 2006).
Elevation (m) (min / max): Provincial:  10 / 10
Known Pests:
Pollen Vector:
Provincial Inventory
Inventory Priority: A - Highest
Ownership of occurrences (Known locations): Mostly national government
Inventory Need: While the possibility remains that new sites for Minuartia pusilla can still be found, inventory effort has been far-ranging and comprehensive, and it seems questionable if further effort is warranted. However, periodic surveys are recommended to monitor habitats for change in case new recruitment of M. pusilla has occurred.
Inventory Comments: Since Minuartia pusilla was discoved in BC in 1977, botanists have searched intensively around Victoria but no additional populations have been found. Since 1997 over 150 person search hours by qualified individuals have been conducted at the most likely sites including Trial, Discovery, Griffing, Calmer and Saturna Islands, Alpha Islet, Harling and Saxe Points, and Uplands Park. Adolf and Oluna Ceska conducted another detailed survey in 2002. In 2004, other specimens of Caryophyllaceae at the BC Provincial Museum were checked to see if any specimens of M. pusilla had been misidentified or overlooked, but none were found (Parks Canada Agency 2006).
Economic Attributes
Provincial Economic Comments: There are no known commercial or cultural uses for Minuartia pusilla, but some members of the genus are favourite horticultural rock garden species (COSEWIC 2004j; Parks Canada Agency 2006).
Endemic: N
Disjunct, more common elsewhere: Y
Peripheral, major distribution elsewhere: Y
Authors / Contributors
Global Information Author:
Last Updated:
Provincial Information Author: Christy, John A.
Last Updated: Mar 20, 2008
Last Literature Search:
References and Related Literature
B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC.
Baskin, J.M. and C.C. Baskin. 1987. Seed germination and flowering requirements of the rare plant, Arenaria fontinalis (Caryophyllaceae). Castanea 52(4): 291-299.
COSEWIC. 2004j. COSEWIC assessment and status report on the dwarf sandwort Minuartia pusilla in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 17 pp.
Costanzo, B. 2002e. Stewardship Account for Annual Sandwort Minuartia pusilla. Prepared for the B.C. Conservation Data Centre and the Garry Oak Ecosystems Recovery Team. Sponsored by the Habitat Stewardship Program, Gov. Can., and Nat. Conservancy Can. Victoria, BC. 12 pp.
Douglas, G.W., D. Meidinger, and J. Penny. 2002. Rare Native Vascular Plants of British Columbia, 2nd ed. B.C. Conserv. Data Centre, Terrestrial Inf. Branch, Victoria. 358pp.
Douglas, G.W., G.D. Straley, D. Meidinger, and J. Pojar, eds. 1998. Illustrated Flora of British Columbia, Vol. 2, Dicotyledons (Balsaminaceae through Cucurbitaceae). B.C. Minist. Environ., Lands and Parks, and B.C. Minist. For. Res. Program. 401pp.
Fairbarns, M. 2005h. Demographic and Phenological Patterns of Minuartia pusilla (Dwarf Sandwort). Aruncus Consulting, 776 Falkland Road, Victoria, BC.
Flora of North America Editorial Committee. 2005. Flora of North America North of Mexico. Vol. 5. Magnoliophyta: Caryophyllidae: Caryophyllales, Polygonales, and Plumbaginales. Oxford Univ. Press, New York. vii + 656 pp.
Maslovat, C. 2009. Guidelines for Translocation of Plant Species at Risk in British Columbia. B.C. Minist. of Environ. Victoria, BC.
Meinke, R.J. and P.F. Zika. 1992. A new annual species of Minuartia (Caryophyllaceae) from Oregon and California. Madroņo 39 (4): 288-300.
Parks Canada Agency. 2006. Recovery Strategy for Multi-species at Risk in Vernal Pools and Other Ephemeral Wet Areas in Garry Oak and Associated Ecosystems in Canada. Species at Risk Act Recovery Strategy Series. Ottawa: Parks Canada Agency. 73 pp.

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. Species Summary: Sabulina pusilla. B.C. Minist. of Environment. Available: (accessed Apr 21, 2024).