Yellow Montane Violet (Viola praemorsa) is a hairy, perennial herb with egg-shaped to lance-shaped basal leaves and a short stem that is leafless or bears a few reduced leaves. Its showy, yellow flowers are borne singly at the end of long stalks which emerge from the axils of leaves. Yellow montane violet also produces less conspicuous cleistogamous flowers, which lack showy petals and are borne on short stalks near the base of the shoot. In both conventional and cleistogamous flowers, the ovary ripens into a dry, 6-11 mm long capsule containing several dark-brown seeds.
Throughout this report the name yellow montane violet refers specifically to the subspecies praemorsa found in British Columbiaand only includes the entire species when considering its global range.
Distribution
Yellow montane violet occurs from Vancouver Island to California, chiefly west of the Cascades. In British Columbia, yellow montane violet is found only along the southeast coast of Vancouver Island and on adjacent islands in the Strait of Georgia. The nearest non-Canadian population is about 100 km to the south, on the other side of Puget Sound. The current Canadian extent of occurrence is about 450 km². The historic extent of occurrence was approximately 2,400 km². The greatest decline in extent of occurrence occurred between 1960-1990. The area of occupancy as based on a 1x1 km grid is 14 km² and based on a 2x2 km grid is 56 km². The actual area of habitat occupied is < 20 ha.
Habitat
In British Columbia, yellow montane violet occurs in Garry oak woodlands and maritime meadows. Most microhabitats occupied by yellow montane violet have shallow soils over bedrock, are relatively level or south-facing, have little or no shrub cover and have an abundant cover of herbaceous species. In spring, the herb layer is dominated by native forbs. In summer, the native herbaceous layer is replaced by a diverse assemblage of forbs and grasses.
The amount of potential habitat has declined greatly over the past century as coastal areas in southeast Vancouver Islandhave been developed for residential and recreational use. Most of the remaining habitat has been heavily altered through invasion by exotic grasses and shrubs.
Three populations have been lost to property development. Most of the remaining populations are secure from development, at least over the next 10 years.
Biology
Shoot dormancy begins to break in March when the soil begins to warm up with the spring weather. Plants are fully leafed out by late April or early May. Foliage begins to wither by mid to late June and the shoots die back by mid to late July as the summer drought deepens. Plants often grow for several years before reaching flowering size. Fruit dispersal occurs as the desiccating capsules rupture abruptly, explosively dispersing seeds as much as 1 metre. The seeds are hard and shiny and bear pale terminal fat bodies (elaiosomes) that attract ants,that carry the seeds slightly further from the parent plant. Yellow montane violet is incapable of clonal growth or asexual reproduction.
Population sizes and trends
There are 14 extant populations and, based on recent data, approximately 32,000-49,000 flowering plants inBritish Columbia, with about 80-90% of the population of this subspecies concentrated in the two largest populations. The actual area of habitat occupied is < 1 km². The number of populations has been in slow decline – five populations have disappeared but none of these have been lost over the past 10 years.
Limiting factors and threats
The impacts of invasive species (particularly exotic grasses) and altered fire regimes pose the greatest threats to yellow montane violet. The absence of First Nations burning has shifted vegetation structure, favouring shrub and tree species that had been held in check by frequent ground fires used to stimulate production of food species. At some sites a fire-intolerant native shrub appears to have expanded into most of the habitat formerly available to yellow montane violet.
Trampling damage along human foot paths has affected a significant proportion of some populations. As well, several populations are so small that they are particularly vulnerable to stochastic events.
Special significance of the species
The British Columbia populations are of scientific interest because they are disjunct from the species’ main range and may be genetically distinct as a result.
Existing protection or other status designations
Yellow montane violet was initially assessed by COSEWIC in 1995 as Threatened in Canada and the status was re-examined and confirmed in 2000. It was subsequently listed under schedule 1 of the federal Species at Risk Act (SARA). The British Columbia Ministry of Environment considers yellow montane violet to be a "Red-listed" (threatened/endangered) taxon in British Columbia. Yellow montane violet is the subject of a multi-species recovery strategy along with other Garry oak woodland species.
