Vaccinium vitis-idaea L., Cowberry

Account Summary

Growth form and preferred habitats

Cowberry can very easily be identified throughout the year by its broad, oval, evergreen leaves, dark green above and paler with black glands below. In Britain, and locally also in Fermanagh, this creeping, evergreen, rhizomatous, up to 30 cm tall subshrub has a remarkably similar distribution to that of another, even more prostrate species of the same habit − Empetrum nigrum (Crowberry). In phytogeographical terms, both belong to the circumpolar boreo-arctic montane element and, in B & I, they are chiefly confined to the well-recognised 'edge communities' on upland wind-exposed scarps (including sea cliffs), rocky acid heaths on upland moors and mountain summits (New Atlas). However, in addition to such wind-dried heathy sites, in Fermanagh, V. vitis-idaea also grows over rock outcrops on damp-but-drained heaths around lakeshores. This happens across the Western Plateau and especially in the Lough Navar area of the VC.

The soils in which Cowberry grows range from pH 3.5-6.8 (Ellenberg 1988; Grime et al. 1988) but, in Fermanagh, the species is confined to the extreme acid end of this spectrum and it is seldom observed in soils over pH 4.0 and then only when the substrate is overlying limestone. The humus-rich soils it frequents are typically in half-shade, constantly damp or wet throughout the year, although from their position, always quite porous and free-draining. Soils in the more wind-swept, exposed sites will also become air-dried to some extent whenever the sun shines.

In every site where it occurs in Fermanagh, V. vitis-idaea co-exists and competes with two very much more common ericaceous subshrubs, V. myrtillus (Bilberry) and Calluna vulgaris (Ling). Grime et al. (1988) have described V. vitis-idaea as being, "intermediate between a stress-tolerator and a stress-tolerant competitor". This summarizes very well the situation we observe in the field, in that Cowberry appears more tolerant of wind and drying soil conditions than V. myrtillus in exposed sites, and considerably more so than the most competitive species of the three, C. vulgaris.

The ecological tolerances of Cowberry suggest that in B & I it might eventually join V. myrtillus in colonising the less shaded areas of pine and spruce plantations in upland blanket bog peatlands, especially when such coniferous forestry is continued into a second generation of trees (Ellenberg 1988, p. 531).

Fermanagh occurrence

In terms of the frequency of the three B & I Vaccinium species which occur in Fermanagh, a very small margin (just three records), separates V. vitis-idaea from V. oxycoccus (Cranberry), making the former the least frequent of the Vaccinium species trio. The local distribution of Cowberry is more upland and restricted of these two mentioned species, however, it being recorded in just 32 Fermanagh tetrads (6.1% of the total in the VC), whereas V. oxycoccus is known from 48 tetrads.

Vaccinium myrtillus and V. vitis-idaea are the most abundant ericaceous dwarf shrubs in the mountainous regions of C Europe as well as in the boreal and sub-arctic regions of N Europe, where they commonly co-exist and are widespread both in the understorey of coniferous forests in montane and subalpine zones and in treeless open 'tundra' habitats at higher altitudes (Ritchie 1955b; Renato et al. 2004). However, in NW Ireland, where truly high mountains do not exist and where in W Fermanagh the Atlantic Ocean is within 15-20 km distance, the only site in the VC where Cowberry occurs in woodland is in the Correl Glen NR. Here, red sandstone scarps occur under the canopy of humid, upland oak-birch mixed woodland festooned with bryophytes and filmy ferns at the lower end of a very damp glen on the Western Plateau. V. vitis-idaea grows here both over rocks on the woodland floor and, very rarely, also as an epiphyte on tree trunks.

Locally, Cowberry has one other interesting, very isolated Fermanagh outlier, on a scarp of rather lower altitude at Drumskinny, which lies to the north of Kesh and Ederny, to the east of Lower Lough Erne. Finally, V. vitis-idaea appears in small quantity on eroded peat on one stretch of raised bog in Glen West Td, in the far west of Fermanagh.

Mechanisms of co-existence of similar species

While the results of many studies indicate areas of similarity and overlap between V. vitis-idaea and V. myrtillus in terms of their plant structure, biology and habitat ecology, equally there are sufficient differences in these areas plus in their reproductive systems, ecological requirements and tolerances, or they could not co-exist in the same community and site and remain separate species. Ecological theory suggests there are two principal explanations for co-existence of similar or closely related species in a community: a. habitat differentiation − meaning that species utilize different portions of the available habitats; or b. resource differentiation − in which species partition the limiting resources in such a way that each is limited by a different component of the available resources or inherent environmental pressures (nutrients, light, temperature/shelter, water, fire, grazing pressure, disturbance and so on).

Shmida & Ellner (1984) found that differences in 'life-history strategy', such as availability of seed from nearby habitats, differences in demographic response to environmental fluctuations and turnover in species composition between different habitat patches (ie 'patch dynamics') were all relevant to the co-existence of similar or closely related species.

Significance of the evergreen habit

The most immediately obvious differences between the two Vaccinium species here under consideration is in their morphology and life-form: V. vitis-idaea has thick, glossy, leathery, evergreen, two or three ranked leaves, while V. myrtillus has much thinner, more herbaceous, deciduous (or very occasionally semi-evergreen) leaves, which are much shorter lived, each leaf typically lasting less than one year. By definition evergreens are species that maintain a cohort of leaves for more than one year (Chabot & Hicks 1982).

Using a mathematical model, Monsi (1968) showed that plant growth is largely determined by the partitioning of the net photosynthetic gain into new photosynthetic and non-photosynthetic tissues, and by the turnover rate of the photosynthetic parts of the plant. The deciduous leaf habit requires a replacement of the photosynthetic system after every production term (ie the annual cycle of growth). This necessity slows down the growth of deciduous species in comparison with plants of evergreen habit, as demonstrated for instance by Beech (Fagus sylvatica ) versus Spruce (Picea spp.) trees, and in this case, V. myrtillus growth slows in comparison with V. vitis-idaea (Schulze et al. 1977).

A study by Karlsson (1992) of leaf life span measurements for 16 evergreen shrubs in the Ericaceae and Empetraceae, made in the European Alps and in C & N Europe, found that mean leaf longevity for each shrub species varied between 1.4 and 3.8 seasons and that leaf persistence was consistently greater further north. Evergreen leaves of V. vitis-idaea were retained for between 2.0 and 3.8 seasons, and at each of three latitudes studied, Cowberry leaves functioned the longest of all of the 16 shrub species that were examined. However, the figures observed for shrubs are much lower than for the needles of evergreen conifers such as Pinus and Picea, which often survive for 4-10 years (Karlsson 1992).

Plant nutrition and evergreen leaves

Leaf characteristics have been shown to be influenced by different nutrients. One of the earliest suggestions was that soils low in potassium supported a more evergreen community (Harper 1914). Loveless (1961, 1962) showed a proportional increase in the degree of sclerophylly occurred with a decrease in leaf phosphorus below 0.3%. Sclerophyllous leaves are hard in texture and have cells with thick cuticles, small lumens (ie cell interior volumes) and reduced intercellular spaces, allowing the plant to be much more resistant to drought.

Several hypotheses have been raised to explain the ecological significance

and benefit to the plant of the evergreen habit in terms of nutrient conservation and improved carbon balance − both of which give advantages to plants in environments where low nutrient levels limit leaf growth. The evergreen habit might also be an adaptation to more general environmental stress. Chabot & Hicks (1982) reviewed this topic, listing and discussing eleven hypotheses along these lines, most of which are not mutually exclusive.

The evergreen habit has long been regarded as an adaptation to nutrient-poor habitats, conferring an ecological advantage over deciduous plants, or over those species with less persistent leaves. The adaptive makeup of the evergreen plant involves: 1. low capacities to photosynthesize and to absorb nutrients; 2. a slower turnover of plant parts, combined with a high re-absorption of minerals from senescing leaves; and 3. storage of carbohydrates and nutrients in old evergreen leaves (Gerdol et al. 2000). A further advantage of evergreen species that reduces loss of minerals from the ecosystem is year-round leaf drop. Through a gradual leaf fall, combined with a subsequent slower decay rate than for deciduous leaves, small amounts of nutrients may be made available to the roots of evergreen species throughout the whole year. This will be particularly important in a mild, temperate climate like that of Fermanagh, with moderate to heavy rainfall, where the growing season is relatively long and leaching of soluble minerals from decaying litter and from the soil is rapid (Monk 1966).

The potential ecological benefit of the evergreen life-form was demonstrated by Karlsson's (1992) study that found leaf life span of evergreen shrubs increased with decreasing soil nutrient status, ie leaves were longer-lived in wet bogs than in drier heaths, and likewise at high altitudes compared with lower montane levels. Evergreen shrubs also tend to dominate dry heathlands, being well adapted to drought stress, probably through being better able to maintain a positive net carbon dioxide balance at low water potentials. Paradoxically, evergreen shrubs also dominate many waterlogged soils, since these conditions can lead to conditions of physiological drought. This feature of evergreens has been known since Schimper's days in the late 19th century, resulting in the recognition of the 'peinomorphosis adaptation' typical of evergreen bog species, which develop plant growth forms and leaf types similar to those of desert perennials (Gerdol et al. 2000).

Different types of evergreen leaves

At the same time, it clearly emerges from many studies that all evergreen leaves are not the same, eg xeromorphs are drought resistant, while the superficially similar life-form, sclerophylly, may relate more to herbivore deterrence and the reduction of nutrient leaching in wet, infertile soil situations. Thus the various anatomical and morphological structures that relate to shrub leaf life span cannot necessarily be explained by a single hypothesis. The same may also be said of herbs; no general patterns of leaf longevity appear in them either (Diemer et al. 1992).

Experiments in subarctic shrub communities

A number of studies lasting 5 or more years have been made examining annual variation in growth and reproduction of subarctic shrub communities dominated by co-existing V. vitis-idaea, V. uliginosum and Empetrum nigrum, and in which V. myrtillus is often also present. These investigations found that responses to experimental manipulation of temperature, water, nutrient levels (in some cases only N, or N & P), and species composition (ie the selective removal of above-ground parts of same or neighbouring species), produced results that were highly complex and extremely difficult to predict. The complexity arose through varying species-specific patterns of growth, great year-on-year variation, and high numbers of interactions between the four factors mentioned (Parsons et al. 1994; Shevtsova et al. 1995 & 1997; Leith et al. 1999).

Elevated temperature and increased nutrient level both produced the expected increase in total above-ground biomass, canopy height and rate of nutrient cycling, but there was little or no consistency in the effect this had on the species competitive outcome and dominance. Nutrient addition did lower species richness, but mainly through its negative impact on the mosses and lichens of the ground flora, a consequence of increased shading by the canopy of growth-stimulated dwarf shrubs (Press et al. 1998). These latter workers also noted that their measure of plant cover revealed an accumulation of litter and standing dead material in response to increased nutrient and temperature levels, operating both singly and in combination, suggesting a faster rate of turnover of plant material in the dwarf shrub community under these treatments.

Although temperature appeared to have a greater stimulating effect on dwarf shrubs than nutrient additions in these higher latitudes and altitudes studies, it is likely that under warmer, more mesic temperate conditions, nutrients will become proportionally more important, affecting comparative growth rates and perhaps also the competitive relationships between these dwarf shrubs. The effect of additional water produced surprisingly little response in the subarctic dwarf shrub vegetation, despite the experiment being carried out in one of the driest parts of Scandinavia (Press et al. 1998).

Comparative evergreen/deciduous nutrient-use efficiency: A similar study in a subalpine heath in the Dolomites in N Italy comparing the water- and photosynthetic nutrient-use efficiency in co-existing V. vitis-idaea and V. myrtillus. This found as expected that deciduous V. myrtillus produced the higher rates of net photosynthesis, and that this was positively correlated with leaf nutrient-status and with carbon dioxide concentrations within the leaf. The percentages of N (nitrogen) and P (phosphate) pools reabsorbed from senescing leaves was also somewhat higher in the deciduous species. Lower concentrations of P in senescing evergreen leaves showed however, that V. vitis-idaea was more proficient at re-absorbing this element (but not N), when compared to the deciduous species, and the evergreen shrub had a higher carbon gain per unit foliar N and P, due to a longer mean residence time of both nutrients in the plant tissues (ie it conserved these nutrients better).

The study did not detect any differences in water-use efficiency between the two shrub species, either on an instantaneous or a long-term basis, but this is probably because there was no sign of any water deficiency in the habitat throughout the growing season studied; there were no appreciable dry periods except at the very end of the season when V. myrtillus had already shed most of its leaves but V. vitis-idaea was still active (Gerdol et al. 2000). However, in drier, perhaps more wind-exposed, or in semi-arid or arid conditions, it is highly likely that possession of evergreen or sclerophyll leaves may serve a different ecological role, functioning then in a water-conservation mechanism. In north-central Florida, for example, deciduous species predominate in mesic fertile sites, while evergreen plant communities segregate off to occupy dry, sterile sites, a familiar enough pattern worldwide (Monk 1966).

Gerdol and co-workers (2000) concluded that evergreen V. vitis-idaea is competitively advantaged over deciduous V. myrtillus, but only in extremely nutrient-poor habitats, and especially so when the latter are phosphorus-limited. However in terms of their carbon economy (ie photosynthetic assimilation and storage), the co-existence of the two species in mixed communities surely must also reflect some degree of niche differentiation with respect to their light regime, apart that is, from the differing duration of their assimilation period mentioned above.

A further study in treeless subalpine heath on three differing soils carried out in the Italian SE Alps by Gerdol and co-workers (2004), looked at both above-ground and below-ground biomass of V. vitis-idaea and V. myrtillus in relation to manipulated soil moisture and nutrient content. Results indicated that V. myrtillus was primarily P-limited and V. vitis-idaea primarily N-limited. Water content affected the distribution of the two shrubs in a similar way, both species producing the lowest biomass of the experiment when growing on peat, possibly due to a toxic effect of waterlogging in wet substrates. Higher P-availability in the soil enhanced V. myrtillus rather than V. vitis-idaea, the presence of which is less distinctly related to soil nutrient content.

Carbohydrate cycle phenology

Deciduous species generally have higher photosynthetic capacities than evergreen species and require higher photon flux densities (ie light intensities) before photosynthesis in individual leaves becomes light saturated. When photosynthetic performance was examined in situ in a subarctic dwarf-shrub heath, evergreen V. vitis-idaea assimilated about one fifth of its yearly carbon gain during periods when the related deciduous species V. myrtillus and V. uliginosum were leafless (Karlsson 1989). Although it would need to be investigated, it seems very likely this fraction could be even greater under temperate conditions, and might be sufficient to significantly affect the competitive outcome between evergreen and deciduous species at least at the beginning of the growing season.

On the other hand, carbon lost from evergreen leaves through respiration during the winter months will undoubtedly reduce the gain from the longer growing season in more temperate latitudes. Another finding was that the seasonal photosynthetic productivity of the deciduous V. myrtillus was more light limited than that of the evergreen V. vitis-idaea under most natural conditions (Karlsson 1989).

A Scottish Vaccinium phenology study: Carbohydrate content measured in samples of three species of Vaccinium collected from an exposed Scottish cliff ledge at 700 m on Ben Lui, Perthshire at intervals of 2 to 8 weeks over a period of least 16 months found that all three subshrubs followed a similar cycle to one another in both their aboveground and underground parts (Stewart & Bannister 1973). A rapid, substantial increase in their carbohydrate reserves occurred early in the spring. In deciduous V. uliginosum for instance, this 'spring rise' occurred between the end of April and the third week in May, before its leaves were open. The spring rise occurred even earlier in V. vitis-idaea and V. myrtillus, both of which possess at least some photosynthetic tissue at this time of year - ie V. myrtillus has wintergreen, barkless stem tissue, while V. vitis-idaea has evergreen leaves. This was followed by a rapid drop in carbohydrate content later in the spring, or the early summer in the case of V. uliginosum, and in the below-ground parts only of V. vitis-idaea. A general increase in carbohydrate levels then occurred during the months when all three plants bear leaves (referred to as 'the summer rise'), followed in V. uliginosum by 'the winter fall' after the end of October, when respiration continues but temperature and other conditions no longer favour photosynthesis.

Carbohydrate levels in V. vitis-idaea and V. myrtillus actually begin dropping earlier than in V. uliginosum, beginning to occur around the end of August. In Cowberry this continued only until the first week in November and the fall in stored carbohydrate is occasioned by an autumn flush of growth (Ritchie 1955 b). In V. myrtillus the dropping levels of carbohydrate reserves ("the winter fall") continues until the "spring rise" in the second week in February, and the causes are an autumn flush of growth followed by subsequent respiratory losses during the winter months (Stewart & Bannister 1973).

Leaf decomposition and nutrient release

Against the trend favouring possession of evergreen leaves is the considerably greater length of time required for leathery leaf litter to decompose and release nutrients bound up in the dead tissues. This includes time for the water-soluble nutrients to leach into the soil and become re-available to living roots, ie to recycle, and also time for the mass of such dead residues to physically disappear from the soil surface, rather than accumulate in a deepening litter layer that might inhibit other species and affect moisture soil relations and root nutrient uptake (Monk 1966).

Sexual and vegetative reproduction

As discussed in detail for V. myrtillus (see species account), over a wide geographic area of the northern hemisphere seed of V. vitis-idaea is either absent from the soil, or is present only in very small quantity, so that reproduction must primarily be vegetative. This is accomplished by branching and fragmentation of its shallow, underground rhizome (Vander Kloet & Hill 1994).

The shrub usually flowers sparingly in B & I, only one to three blossoms appearing on each pendulous raceme cluster, although the species is capable of producing up to twelve flowers on each (but more normally five or six). It is reported that flowering occurs in spring and again in early summer (Ritchie 1955b; Grime et al. 1988), but the plant is much too rarely recorded in Fermanagh to determine if this is the case. The N American form of the species, subsp. minus, differs in flowering only once, as one might expect of a plant with a largely subarctic, short season distribution (Hall & Shay 1981).

According to Ritchie (1955b), Cowberry plants do not produce many flowers until they are somewhere between 5 and 10 years established. Russian studies put the time of first flowering considerably later than this, most plants requiring 14 to 20 years growth before reaching sexual maturity (Hall & Shay 1981). The flowers are said to be homogamous, or almost so, the sexual parts ripening more or less simultaneously. Pollination is either by insects (commonly bees and butterflies), or involves selfing, since the species is partially self-compatible. Like V. myrtillus, Cowberry is reported to habitually inbreed, but in V. vitis-idaea this is largely or entirely due to the scarce occurrence of many of the over-dispersed populations in B & I, making cross-pollination a relatively rare event (Ritchie 1955b).

V. vitis-idaea suffers a drastic decrease in fertility after self-pollination when compared to cross-pollination, another limiting property it shares with V. myrtillus. Partial self-sterility in both these Vaccinium spp. is due to embryo abortion early in seed development (ie early inbreeding depression). Guillaume & Jacquemart (1999) hypothesized that this is based on the expression of partially recessive lethal alleles during embryo development.

Fruit and seed production

In respect to fruit production, toxic properties of the berries, seed transport (mainly by birds), germination, rarity of seedlings and their slow rate of establishment, there appears to be very little physiological or ecological difference between V. vitis-idaea and V. myrtillus (Ritchie 1955b, 1956; Hall & Shay 1981). Obviously since the former subshrub is much rarer, particularly further south towards the limit of its range in England, Wales and throughout Ireland, under the prevailing environmental conditions, opportunities for successful sexual reproduction and genetic recombination are even more unlikely in Cowberry than in Bilberry. Nevertheless, in parallel with other arctic-alpine plant species surviving changing conditions in B & I from the Late-glacial period to the present day, V. vitis-idaea demonstrates the characteristic tenacity all these species share, being able to maintain existing, but perhaps shrinking populations, even when sexual reproduction and the ready transport which seed provides for the colonisation of fresh sites becomes severely limited and they become increasingly dependent upon vegetative reproduction for their survival.

Hybrid

In Britain, a very rare intermediate hybrid (V. × intermedium Ruthe) is formed with V. myrtillus, but it has never been recorded anywhere in Ireland. The hybrid is widespread in C & N Europe (Stace et al. 2015).

Irish occurrence

In the rest of Ireland apart from Fermanagh, the distributions of V. vitis-idaea and Empetrum nigrum do overlap, but the latter species is very much better represented throughout the Republic of Ireland. In comparison, south of the International border V. vitis-idaea is confined to sites in six mountainous regions in the Donegal, Sligo-Leitrim, Connemara, Wicklow, Limerick and Waterford areas, although there are old records in the Irish Census Cat. from three other VCs further south (H7, H10 & H13). In Co Limerick (H8) for example, Cowberry was found by Stelfox in the western portion of the Galtee mountains (Praeger 1946), and one small, very inaccessible colony survives there (Reynolds 2013). Elsewhere none of these southern records have been refound for many years and they may well be extinct (Scannell & Synnott 1987). In the northern province of Ulster, V. vitis-idaea has a very much wider, although still a rare and mainly upland occurrence, which is strikingly coincident with that of Empetrum nigrum (Hackney et al. 1992).

British occurrence

Although managing to persist in single isolated hectads in S Devon and S Somerset (VCs 3, 5), further north V. vitis-idaea is widespread in much of upland Britain and has its greatest presence in Scotland. In England, it is most abundant in the SE Pennines and the Pennines in Cumbria. Cowberry is described as "not infrequent" on mountains in the Lake District and it descends to near sea-level close to Morecambe Bay (Halliday 1997). V. vitis-idaea is described as rare, sparse and declining on the Pennine Uplands of Co Durham (23 tetrads mapped; Graham 1988, p. 155), while on the other hand in Northumberland the species is described as being scattered and frequent and plentiful on higher parts of The Cheviot (being mapped in 93 five km squares, plus three pre-1968 (Swan 1993, p. 188)). The New Atlas gives the species a low change index value of ‑0.18, which suggests that overall, at the hectad level of discrimination, the distribution has not significantly altered since the 1962 BSBI Atlas (Preston et al. 2002; Walters & Perring 1962).

European and world distribution

Hultén (1971, Map 69) illustrates the distributions of the two closely related subspecies, the circumpolar subsp. minus overlapping the more southerly subsp. vitis-idaea in Scandinavia, where introgression between the subspecies occurs; they co-exist again in Asia in parts of E China and Japan. In W Europe, V. vitis-idaea is widely distributed in arctic, boreal and temperate areas and towards the south of its range has montane and alpine outliers in France, N Spain and N Portugal. The same form of the plant also has further outliers east of the Black Sea (Hultén 1971; Hultén & Fries 1986, Map 1460).

The overall picture of the total species range fits the familiar pattern of the arctic-alpine flora element of Matthews (1955), the plant having a significant portion of its geographical range lying north of the tree limit, although this itself is a very variable and difficult concept to define. For good accounts of the problems, historical and otherwise, in delimiting arctic and alpine timberlines, see Barry & Ives (1974), Larsen (1974) and Wardle (1974).

Uses

Cowberries are very sharply tart until they are subjected to frost, so they become somewhat more palatable later in the winter period. Despite their strongly astringent nature, in N Europe, and especially in Scandinavia, there is a tradition of collecting them by combing them from the branch ends. The berries are used to make jelly, or mixed with other wild fruits, such as rose hips, to make jam. Cowberries are also widely processed and marketed in Japan and are commercially harvested in parts of Scandinavia, Russia, Alaska and Canada. Considerable amounts of fruit are imported into the United States annually. Much of this imported fruit is consumed by people of Scandinavian descent who use the so-called 'Swedish lingenberry' in traditional dishes.

V. vitis-idaea s.l. has the potential for more extensive commercial development and some native stands in the subarctic could be managed with a minimum of cultivation, as are those of Low sweet blueberry. The feasibility of expanded commercial operations has being trialed in parts of North America (Tirmenstein 1991).

Porsild (1937) pointed out the valuable antiscorbutic properties of Cowberries due to their high vitamin C content. In comparison with V. myrtillus, V. vitis-idaea appears to have very little traditional use in herbal medicine, the only reference to it uncovered by Allen & Hatfield (2004) being as an ingredient of an inhalant for a blocked nose or for treating blocked sinuses in Cumbria.

Names

The Latin specific epithet, 'vitis-idaea', is a name first used by Theophrastus and it means 'vine of Mount Ida or Idaea', a reference to a Greek mountain where presumably the plant grows, or once did (Gilbert-Carter 1964). The Mountain Flora of Greece, 1 (Strid 1986, p. 741) mentions several sites for the species, but it does not appear to include any Mount Ida!

Twelve English common names are listed by Britten & Holland (1886) including 'Flowering Box', 'Brawlins', 'Clusterberry', 'Ling-berry', plus some names shared with other species of the genus. The most familiar and entirely inappropriate name, 'Cowberry', is said to have arisen from a 19th century blunder which confused the genus name 'vaccinium', the fruit of the whortle, with 'vaccinum', the Latin for 'what belongs or pertains to a cow' (Prior 1879, p. 55; Grigson 1974).

Threats

Since V. vitis-idaea is already very local and sparse, only occurring in out of the way sites, it is somewhat protected by these factors. The lack of effective seed regeneration however, means that once populations are lost for any reason, they are not naturally replaced and thus the species is vulnerable to any change in the environment.

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