BC Conservation Data Centre: Species Summary
Orthocarpus bracteosus
rosy owl-clover
| Scientific Name: | Orthocarpus bracteosus Benth. | ||||||||||
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| English Name: | rosy owl-clover | ||||||||||
| 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: | ORTHBRA | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G3 (Jan 2025) | ||||||||||
| 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: | Orthocarpus bracteosus is a rose-purple annual herb that grows from an erect stem and is 10-40 cm tall. The B.C. population averages 5 cm tall (maximum 9 cm). The plant is short-hairy and purple-tinged, and leaves are alternate, stalkless, linear to lance-shaped, and 1.5-3.5 cm long with short-spreading or gland-tipped hairs. The upper part of each leaf is three-cleft. The flowers are grouped into dense, prominently bracted, densely hairy, and glandular terminal spikes (3-15 cm). The flowers are rose-purple or sometimes white or cream, hairy, 12-20 mm long, tube-shaped, and exserted from bracts. Sepals are tube-shaped, 6-10 mm, green and glandular-hairy. The bracts are green or purple-tinged, and the upper bracts are 3-lobed. The fruit is an elliptical capsule. | ||||||||||
| Similar Species: | Potentially co-occurring similar species include Castilleja ambigua, C. attenuata, Triphysaria pusilla, and T. versicolor ssp. versicolor. Triphysaria species can be distinguished from Orthocarpus bracteosus by their lower corolla lip, which is strongly three-pouched, and by their anthers, which are one-celled. In Triphysaria and Castilleja, the beak-like upper corolla tips are open and the stigma is expanded, while Orthocarpus has closed tips and a dot-like stigma. The two Castilleja species and Triphysaria versicolor ssp. versicolor have white or yellow corollas in contrast to the rose-purple ones of O. bracteosus. Triphysaria pusilla has red-purple corollas, but they are much smaller (4-6 mm) than the corollas of O. bracteosus (12-20 mm). Without flowers, these taxa can be difficult to distinguish. | ||||||||||
| Provincial Reproduction Comments: | Asexual reproduction does not occur in Orthocarpus bracteosus. No specific information exists on the pollination ecology of the species. Flowers are chasmogamous, but it is not known if inbreeding or outbreeding occurs. Most species of this group (owl-clovers, Orthocarpus, Castilleja, and Triphysaria) are predominantly outbreeders. Orthocarpus bracteosus has showy flowers and a clumped distribution, which are characteristics of outbreeding systems and are known to promote efficiency in cross-pollination (Atsatt 1970; COSEWIC 2004k). Related outbreeding owl-clovers are primarily pollinated by honeybees and native bee species (COSEWIC 2004k). The genetic variability in the B.C. population of O. bracteosus and its genetic distinctness from southern populations (ca. 300 km away) has not been studied. The white variant of O. bracteosus, sometimes called "variety albus", occurs at Trial Island and may have some taxonomic significance, but no studies have been undertaken to test for microhabitat differences between the typical rose-purple variety and the white variety. | ||||||||||
| Provincial Ecology Comments: | Basic ecological information on Orthocarpus bracteosus is lacking. Seed dispersal is poorly understood. Fairbarns (2005c) summarized four hypotheses that have been proposed for the species' dispersal mechanism: (1) coordinated dispersal whereby seeds of O. bracteosus adhere to pappus bristles of co-occurring Hypochaeris species and are wind dispersed (Atsatt 1965); (2) wind or animal dispersal mediated by reticulations on seed coats, which may improve aerodynamics or adhesion to animal coats (Chuang and Heckard 1983); (3) poor dispersal capability - seeds fall in immediate vicinity of parents (Chuang and Heckard 1983); and (4) water dispersal (Kuijt 1969). Fairbarns (2005c) noted that seeds remained in capsules well into winter, which provides some evidence of poor dispersal capabilities. Furthermore, seed dispersal of Hypochaeris occurs earlier than in O. bracteosus, which suggests that coordinated dispersal does not occur on Trial Island (Fairbarns 2005c). Little is known about the seed bank of O. bracteosus and how it affects population dynamics. Germination occurs after a period of dormancy (Fairbarns 2005c). Fairbarns (2005c) identified four stages of development: seedling, young juveniles, advanced juveniles, and reproductive plants. Orthocarpus bracteosus is a hemiparasite; it can photosynthesize but it receives water and nutrients (and sometimes photosynthates and secondary compounds) through parasitic root connections (Kuijt 1969). Orthocarpus species are reported to be facultative hemiparasites; they can grow and produce flowers without a parasitic host but are usually less robust (Matthies 1997). Fairbarns (2005c) did not observe any evidence of fungal infection or herbivory on foliage, flowers, or fruits of O. bracteosus. The effect of competition from introduced and native vernal pool species on O. bracteosus has not been studied. | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
Agriculture / Pasture/Old Field / Unknown
Anthropogenic / Roadside/Ditch / Unknown Grassland/Shrub / Garry Oak Maritime Meadow / Facultative - frequent use |
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| Global Habitat Comments: | Orthocarpus bracteosus grows in seasonally wet meadows, vernal pools, and coastal prairies at elevations ranging from 10 to 2,000 meters (COSEWIC 2004, FNA 2019). | ||||||||||
| Provincial Habitat Comments: | The best descriptor of Orthocarpus bracteosus habitat is "temporary pool" and "grassland/herbaceous". More specifically, the species occupies a very shallow vernal pool, which sometimes is only a moist depression in dry winters. Vernal pools are temporary wetlands, often with distinct boundaries, that form on relatively level sites that are underlain by bedrock or an impervious hardpan layer (Miller et al. 2003). Vernal pools typically occur in areas with Mediterranean climates, and are characterized by winter and spring inundations followed by complete drying in summer. Historical records suggest that O. bracteosus formerly occurred infrequently in a variety of open, winter-wet summer-dry habitats, including ditches, coastal prairies, and open fields (COSEWIC 2004k). Vernal pools in the Victoria area are part of a complex of maritime meadows, coastal bluffs, grasslands, rock outcrops, and forests which make up the Garry oak ecosystem (Fuchs 2001). This ecosystem is very restricted in B.C. - it occurs within the drier subzone of the Coastal Douglas-fir (CDFmm) biogeoclimatic zone - and has been reduced to less than 5% of its original extent (Fuchs 2001). Orthocarpus bracteosus is, therefore, narrowly restricted to vernal pools, a rare land feature with unique climatic and hydrological properties, which occurs within a very rare ecosystem in south coastal B.C. Soils on sites occupied by O. bracteosus are 15-30 cm deep, rich in humus, and slightly disturbed in the winter, presumably by gull pecking (COSEWIC 2004k). The vegetation on these sites is sparse (plant cover attains 20% in summer) and lacks trees, shrubs, and large herbs. Dominant species associated with O. bracteosus are Grindelia integrifolia, Plantago lanceolata, Hypochaeris radicata, and Prunella vulgaris. | ||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
Mar: / Germinating
Apr: Vegetative, Germinating / Vegetative, Germinating May: Vegetative / Vegetative Jun: Vegetative, Flowering / Vegetative, Flowering Jul: Vegetative, Fruiting / Vegetative, Fruiting Aug: Fruiting / Fruiting Sep: Fruiting / Fruiting |
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| Provincial Phenology Comments: | Orthocarpus bracteosus is a short-lived annual herb. Fairbarns (2005c) studied the phenology of O. bracteosus on Trial Island and in ex situ garden plots. Germination may occur in late March, but most germination occurred in April (Fairbarns 2005c). Plants were fully developed by early June after passing through three stages of development (seedling, young juvenile, advanced juvenile). Flower development occurred in late May and early June, and flowering peaked in June. Green fruit capsules were evident in late June or July and matured quickly. Capsules began to dehisce in late July, but dehiscence was gradual, and most seeds were dispersed by November and December. Most plants senesced and died during late July or early August, although some plants started to fade as early as May. | ||||||||||
| Elevation (m) (min / max): | Provincial: 4 / 4 | ||||||||||
| Known Pests: | |||||||||||
| Pollen Vector: | |||||||||||
| Pollinator: | |||||||||||
| Dispersal: | |||||||||||
| Provincial Inventory | |||||||||||
| Inventory Priority: | D - Low | ||||||||||
| Ownership of occurrences (Known locations): | Mostly state/provincial government | ||||||||||
| Inventory Need: | There is low priority for new inventories of Orthocarpus bracteosus. | ||||||||||
| Inventory Comments: | It is not likely that new populations of Orthocarpus bracteosus will be discovered in B.C. Matt Fairbarns (pers. comm. 2004) searched a large number of suitable sites in 2003. The Garry oak recovery strategy has also enabled a concerted inventory of habitats such as vernal pools and coastal prairies, which are preferred habitat for O. bracteosus, by M. Fairbarns and other expert botanists in recent years. New populations would surely have turned up during these searches. Suitable sites have also been surveyed repeatedly since the early 1980s by expert botanists in a series of projects designed to document the distribution of rare plants in open meadows of southeast Vancouver Island and Gulf Islands (Parks Canada Agency 2006c). | ||||||||||
| Economic Attributes | |||||||||||
| Provincial Economic Comments: | No economic attributes are known for Orthocarpus bracteosus. | ||||||||||
| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | Orthocarpus bracteosus occurs in western North America from southwestern British Columbia, Canada south in the United States to northeastern California (COSEWIC 2004, FNA 2019, Jepson 2025). It is introduced in the eastern United States in New York and Maryland (COSEWIC 2004, Weakley and the Southeastern Flora Team 2024). Native range extent was estimated to be approximately 132,000 square kilometers using herbarium specimens and NatureServe Network occurrence data documented between 1984 and 2025 (GBIF 2025, NatureServe 2025, SEINet 2025). | ||||||||||
| Disjunct, more common elsewhere: | Y | ||||||||||
| Peripheral, major distribution elsewhere: | Y | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | Soteropoulos (2025) | ||||||||||
| Last Updated: | Jan 27, 2025 | ||||||||||
| Provincial Information Author: | Bartemucci, P. | ||||||||||
| Last Updated: | Feb 16, 2005 | ||||||||||
| Last Literature Search: | |||||||||||
| References and Related Literature | |||||||||||
Atsatt, P.R. 1965. Angiosperm parasite and host: coordinated dispersal. Science 149: 1389-1390. |
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Atsatt, P.R. 1970. The population biology of annual grassland hemiparasites II. Reproductive patterns in Orthocarpus. Evolution 24:598-612. |
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B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC. |
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Chuang, T.I. and L.R. Heckard. 1983. Systematic significance of seed-surface features in Orthocarpus (Scrophulariaceae - Subtribe Castillejinae). Amer. J. Bot. 70: 877-890. |
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COSEWIC 2004. COSEWIC assessment and status report on the rosy owl-clover Orthocarpus bracteosus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 18 pp. Online. Available: https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/rosy-owl-clover.html (accessed 2025). |
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COSEWIC. 2004k. COSEWIC assessment and status report on the rosy owl-clover Orthocarpus bracteosus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 18pp. |
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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. |
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Douglas, G.W., D. Meidinger, and J. Pojar, eds. 2000. Illustrated Flora of British Columbia, Vol. 5, Dicotyledons (Salicaceae through Zygophyllaceae) and Pteridophytes. B.C. Minist. Environ., Lands and Parks, and B.C. Minist. For., Victoria. 389pp. |
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Fairbarns, M. 2002. Stewardship Account for Rosy Owl-clover Orthocarpus bracteosus. 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. 14 pp. |
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Fairbarns, M. 2003. Status Report on Rosy Owl-clover, Orthocarpus bracteosus, in Canada. Unpubl. rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. Ottawa. 18 pp. |
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Fairbarns, M. 2005c. Demographic and Phenological Patterns of Orthocarpus bracteosus (Rosy Owl-clover). Aruncus Consulting, 776 Falkland Road, Victoria, BC. |
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Flora of North America Editorial Committee (FNA). 2019. Flora of North America north of Mexico. Vol. 17: Magnoliophyta: Tetrachondraceae to Orobanchaceae. Oxford Univ. Press, New York. xxiv + 737 pp. |
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Fuchs, Marilyn A. 2001. Towards a Recovery Strategy for Garry Oak and Associated Ecosystems in Canada: Ecological Assessment and Literature Review. Tech. Rep. GBEI/EC-00-030. Environ. Can., Can. Wildl. Serv., Pac. and Yukon Region. |
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Kuijt, J. 1969. The biology of parasitic flowering plants. University of California Press. Berkely and Los Angeles. |
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Maslovat, C. 2009. Guidelines for Translocation of Plant Species at Risk in British Columbia. B.C. Minist. of Environ. Victoria, BC. |
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Matthies, D. 1997. Parasite-host interactions in Castilleja and Orthocarpus. Can J. Bot. 75:1252-1260. |
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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. |
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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. 2025. Species Summary: Orthocarpus bracteosus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 8, 2026).