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Valeriana officinalis L., Common Valerian

Account Summary

Native, common and widespread. Eurasian boreo-temperate, widely naturalised beyond its native range, including in N America.

1881; Stewart, S.A.; Callow (or Carrick) Hill.

March to November.

Growth form and preferred habitats

An extremely variable, glabrous perennial with stout, robust, erect, almost unbranched stems from 50 to 200 cm tall, and pinnate leaves with 9-13 lanceolate, usually (but not always) toothed leaflets. Butcher (1961) describes the leaves as being, "all pinnate, lower with leaflets toothed on the lower side only". By this he means, the side of each leaflet nearest the leaf base only is toothed.

Plants develop a short, simple rhizome or rootstock that permits a limited degree of vegetative spread by producing short stolons (Grime et al. 1988, 2007; Stace 1997; Sell & Murrell 2006).

Plants in wetland sites are very much taller and have broader, more toothed leaflets than those growing on dry calcareous soils. This size and shape feature is recognised as being related to chromosome number, ie octoploids are present in wet sites, tetraploids on dry ones (New Flora of the BI 1991; An Irish Flora 1996; Parnell & Curtis 2012). The tetraploids are small plants with narrow leaves and they appear confined to dry calcareous ground. However, as pointed out by Webb et al. (1996), intermediates abound in many features in this species and, "more work is required on Irish material". This requirement would need to be met before the current author (RSF) and RHN could feel able to differentiate the two subspecies that have already been proposed. These are subsp. sambucifolia (J.C. Mikan ex Pohl) Hayw., the more common of the two, in damp ground, and subsp. collina (Wallr.) Nyman in dry, calcareous situations (Sell & Murrell 2006).

Perhaps partly as a result of this taxonomic and ecological dichotomy, V. officinalis is frequent in a wide range of moderately fertile, relatively undisturbed rough grassland habitats, including tall herb vegetation in marshes, fens, wet woods, fen carr, riverbanks, ditches and damp grassland, as well as appearing less frequently on dry, calcareous ground (P.J. Wilson, in: Preston et al. 2002). In the Shropshire region of England, Sinker et al. (1985) described it as mostly frequenting, "wet to damp peat, clay or loam soils that are moderately acid to neutral, in sun to half-shade".

The presence and persistence of the species in tall herb vegetation indicates some measure of shade tolerance and ability to set seed under such circumstances, but it does not appear to survive regular levels of repeated grazing, which therefore tends to limit it to rough, marginal ground, or to situations where there is only occasional, light to moderate levels of disturbance that assists Valerian by limiting the vigour of other potentially dominant species thus allowing it to persist (Grime et al. 1988, 2007). Flowering stems of V. officinalis are very much taller than non-flowering ones, ie 150 cm as opposed to around 20-30 cm. As Grime et al. (1988, 2007) also point out, leaves on flowering stems are generally concentrated on the lower half of the stem, a feature that together with the minor degree of vegetative spread the species is capable of, must limit its ability to compete in tall herb habitats. After flowering and fruiting, the aerial branches die off and gradually disappear and the plant overwinters underground. This is another feature that affects the species' competitive ability.

The established strategy of V. officinalis is categorised by Grime et al. 1988, 2007) as C-S-R, meaning it displays a balanced combination of all three basic ecological strategies, Competitor, Stress-tolerator and Ruderal.

Fermanagh occurrence

As one would expect in the hyper-oceanic climate of NW Ireland, the wetland form of the plant is very much more prevalent in Fermanagh. V. officinalis is a familiar and welcome sight in the tall herb community of rough and ungrazed damp grassland, reed swamp, on sedge tussocks and under medium shade in fen carr woodland, as well as on lakeshores and on stream- and river-banks. A dry ground form, probably the tetraploid, occurs on calcareous hills and scree in Fermanagh. Overall, V. officinalis has been recorded in a total of 268 widely scattered Fermanagh tetrads, representing 50.8% of those in the VC.

Flowering reproduction

V. officinalis flowers from late-May to August. The white, or tinged pink or lilac flowers are borne in a broad, flat, many-flowered, loose, compound, 3-forked, corymbose cyme with very narrow bracts immediately below the flowers. The middle flower is the oldest in each ultimate cluster (Hutchinson 1972). According to Grime et al. (1988, 2007) there can be over 100 flowers in an inflorescence. The flowers are bisexual and the individual flower and fruit are remarkable and well worth examining. As described by Melderis & Bangerter (1955), the calyx is superior to the ovary and is 5-lobed at first and inrolled. Hutchinson (1972) memorably describes the inrolled calyx being, "like the fingers of a closed fist". Later, after the ovules in the flower have been fertilised, the calyx rays open out into a feathery pappus of hairs, "like a parachute", as Hutchinson says, attached to the top of the fruit. The ovary contains three locules, compartments or cells, only one of which contains a single, pendulous ovule, the other two being empty (Hutchinson 1972).

The corolla has a long, exceedingly slender tube and five spreading lobes, 5 mm across, from which three stamens and three styles both clearly protrude (Melderis & Bangerter 1955). The corolla lobes are rounded and somewhat unequal (Butcher 1961). Only an insect with a very long proboscis or tongue, and an amazing degree of control over such an unwieldy implement, could gain legitimate access to the flower's nectar food reward, which is contained in a small pouch-like swelling at the base of the corolla tube. Five purple nectar guides lead the insect to the pouch (Melderis & Bangerter 1955). The flowers are scented, and are of course 'designed' to attract insect visitors. They are protandrous, the anthers opening before the stigma lobes are receptive and projecting beyond them. Later, the style elongates so that the stigma lobes reach almost the same level in the flower as the anthers. They are then pollinated by insects transferring pollen from younger flowers, while the old stamens in the same flower curve outwards, avoiding the stigma lobes and allowing cross-pollination to occur (Hutchinson 1972).

The visitors listed by Proctor et al. (1996) include caddis-flies, craneflies and mosquitoes, all of which have relatively short tongues and, in some cases, biting mouthparts. The list also includes the expected long-tongued butterflies and moths who are the principal pollinators. Presumably nectar theft, by boring a hole in the slender corolla tube or the spur, is practised by the shorter-tongued insects mentioned.

After fertilisation, the single-seeded, fruit nutlet is small, (8 × 2 mm), conical in shape, dry, ribbed and crowned by a feathery pappus that about equals the achene (ie single-seeded, dry fruit), that acts like a parachute, enabling wind dispersal to be more effective (Butcher 1961; Hutchinson 1972).

There are a total of eight estimates of seed survival in the NW Europe survey of soil seed banks, all of them indicating that seed is transient, persisting in the soil for less than one year (Thompson et al. 1997).

Fossil history

Fossil fruits and pollen evidence assembled by Godwin (1975) prove that V. officinalis has a very long fossil history in B & I and a presence in both glacial and interglacial stages right to the present day. The fossil record suggests it was abundant in the early stage of the present interglacial in England, zone IV, but was reduced after this until a subsequent increase in zone VI, possibly the result of an upsurge in lake margin vegetation at that time. Thus Godwin concluded V. officinalis has been a persistent native species throughout the Pleistocene period and probably survived here in situ as a periglacial species during glacial phases.

Uses

Valerian root has a long medical history and, like Agrimony (Agrimonia eupatoria), was held in such esteem in medieval times that it was referred to as 'All Heal' (Grieve 1931). Although Valerian has been dropped from modern official pharmacopoeias, drugs obtained from it were previously used to treat psycho-neuroses, and as a sedative and neuralgic pain-killer, particularly appreciated for having none of the after-effects produced by narcotics. Valerian root exudes valeric acid, which smells of rancid perspiration. It was referred to by the old herbalist doctors, Dioscorides and Galen, as 'Phu', presumably an expression of aversion to its offensive smell (Grieve 1931; McLean 1981).

McLean (1981) noted that Valerian was hardly ever cultivated in medieval gardens in Britain, though it did have a great reputation as a heal-all herb. She remarks, "It was not welcomed in gardens, except by those who believed more in a nasty plant's power to harm disease than a pleasant plant's power to do one good. It was generally left on the wild side of the horticultural fringes …". Grigson (1955, 1987) records that as recently as 1916 Valerian root was cultivated on a commercial scale in Derbyshire; it was gathered wild from the woods and transplanted for medicinal use.

Thrisk (1997) has commented and suggested, that from the mid-1990s onwards there has been a renewed cultural preference for herbal remedies, rather than use of synthetic chemical drugs, and since government from time to time promotes alternative agriculture and farm diversification, it is not impossible a revival of some kinds of herbal agriculture could emerge and it might include V. officinalis.

British and Irish occurrence

Common Valerian remains frequent and widespread throughout B & I, but has never been recorded in the Shetland isles (VC 112). Inspection of the New Atlas hectad map indicates there has been a definite, but not massive decline across both Britain and Ireland, most especially noticeable in SE England, during the last 60 years. Presumably, this is due to habitat loss associated with the intensification of farming, drainage and other forms of development (P.J. Wilson, in: Preston et al. 2002).

European and world occurrence

V. officinalis is a variable polyploid complex that belongs to the Eurasian boreo-temperate phytogeographical element. As such, it stretches from N & C Europe from Iceland and Scandinavia southwards to C Spain, S France, most of Italy and to the mountains of Greece. Hultén & Fries (1986) map it stretching eastwards to scattered locations in temperate Asia reaching Japan, and B & I Floras concur (Clapham et al. 1987; Sell & Murrell 2006). It is definitely introduced in E & C areas of N America (Hultén & Fries 1986, Map 1743).

Names

The genus name 'Valeriana' is a medieval name, possibly or probably from the Latin 'valeo' meaning 'to be well' (Gilbert-Carter 1964; Melderis & Bangerter 1955). The Latin specific epithet 'officinalis' is from 'officina', meaning 'druggist's shop', ie the source of medicinal drugs (Melderis & Bangerter 1955).

Grigson (1955, 1987) lists a total of eleven English common names, most of them referring to the herbal healing reputation of the species. Examples include 'All-heal', 'Heal-all', 'Cut-finger', 'Cut-finger leaf' and 'Cut leaf'. Other names allude to the peculiar, somewhat unpleasant, smell of the plant, which is said to be attractive to cats. Vickery (2019) scores considerably higher than Grigson with a total of 20 English common names, although some from N Ireland are probably Gaelic derived rather than English, such as 'Bolaira'. Others are local dialect mis-spellings and mis-pronunciations, corruptions of 'Valerian', such as 'Phillaira' in Co Donegal (H34, H35), 'Villera' in Co Antrim (H39) and 'Valara' in Cumberland (VC 70). The same ideas as to using the herb to heal cuts, and it being a cure-all panacea, plus the rank odour the plant or its root give off that cats appreciate, also apply.

Threats

None.

References

Proctor, M., Yeo, P. and Lack, A. (1996); Stace, C. (1991); Stace 1997; Webb,D.A., Parnell,J. and Doogue,D. (1996); Parnell & Curtis 2012; Grieve, M. (1931); Thirsk, J. (1997); McLean, T. (1981); Vickery (2019); Grigson 1955, 1987), Gilbert-Carter 1964; Melderis & Bangerter 1955; Preston et al 2002; Butcher 1961; Hutchinson 1972; Grime et al. (1988, 2007); Sell & Murrell 2006; Sinker et al. (1985); Sprague 1949; Hultén & Fries 1986; Godwin 1975; Thompson et al. 1997; Clapham et al. (1987).