Rare Species Guide

  Synonyms

Valeriana edulis ssp. ciliata, Valeriana ciliata

  Basis for Listing

Valeriana edulis var. ciliata was not formerly rare in Minnesota, but the nearly total destruction of prairie and fen habitats has reduced populations to small, isolated fragments, many of which cling to existence in embattled habitat remnants on roadsides and railroad rights-of-way. The situation is similar throughout the species' range, especially in Iowa, Ohio, Michigan, Indiana, and Ontario.

The destruction of fen and prairie habitats has come from a different source in recent decades. At least half of the V. edulis var. ciliata populations are associated with prairie strips on railroad rights-of way. These prairie strips have long been unavailable for agriculture and have served as de facto sanctuaries for many native species. However, recent decades have seen railroad companies abandoning and selling the rights-of-way. These rights-of-way and the prairies that occur on them are typically bought by adjacent landowners and converted to crop production.

Our current knowledge of this species reflects an attempt by the Minnesota DNR to inventory these prairie strips before they are destroyed. A number of recently discovered populations have already been lost, especially in Mower, Steele, and Waseca counties. Valeriana edulis var. ciliata was listed as a threatened species in Minnesota in 1984.

  Description

Valeriana edulis var. ciliata is the only indigenous member of this family in Minnesota, and it can be easily identified. Whitish flowers are unisexual with 5 petals, 3 stamens (male, pollen-producing structures), and a 3-lobed stigma (part of female, seed producing structure). Sepals (structures composing the outer whorl of the flower) are modified into distinctive, featherlike bristles that are rolled up in flower but expand when the fruit matures. The flower cluster has numerous later branches that become diffuse with age. Conical taproots and secondary roots are yellow and strongly scented. Leaves are thick, parallel-veined, and fringed with marginal hairs, making the leaves appear to have silver edges. Basal leaves are on short, winged stalks, have a continuous margin, and occasional basal lobes. Stem leaves are smaller, in remote pairs, and divided into pairs of leaflets. Variety edulis is found in western North America and appears to have no contact with var. ciliata. Their distribution follows closely the patterns of Pleistocene glaciation, and it is surmised that these were once a single subspecies that became separated during glaciation (Meyer 1951).

Other common names for the species include tobacco root, edible valerian, and common valerian.

  Habitat

Valeriana edulis var. ciliata appears to favor a moist, sunny, calcareous habitat, including calcareous fens, wet meadows, and moist prairies. Many of these habitats are found along railroad right-of-ways. In these habitats, V. edulis var. ciliata is typically associated with other declining species such as Asclepias sullivantii (Sullivant's milkweed), Cypripedium candidum (small white lady's-slipper), and Arnoglossum plantagineum (tuberous Indian-plantain). In the Paleozoic Plateau of southeastern Minnesota, the species occurs in thin, rocky soil and on cliff ledges associated with dry bluff prairies. Though these bluff settings share a similar pH, they appear much drier than the more typical moist prairie, meadow, and fen habitats. However, plants often seem to be growing in localized microsites along bedrock strata where extra moisture seems to be present.

  Biology / Life History

Valeriana edulis var. ciliata is a long-lived perennial that spreads only by seeds. Judging from the design of the seed with its plumed fruit, it is made for short flights or hitchhiking. Wind or animals that pick up the seeds in their fur likely effect the species' dispersal. A dispersal barrier is fragmentation of prairie remnants, with the accompanying loss of animal corridors and pollinators (Meyer 1951; Voss 1996).

The best time to search for V. edulis var. ciliata is when it is flowering or fruiting from May through early September, though plants are visible May through October.

  Conservation / Management

Valeriana edulis var. ciliata habitat is threatened by conversion to agricultural uses, draining of wetlands, and invasion of non-native plant species, particularly Bromus inermis (smooth brome). The non-native invasive shrub Rhamnus cathartica (common buckthorn) threatens at least one wet prairie population. Another prairie remnant with V. edulis var. ciliata is overgrown with native shrubs following decades of fire suppression. Woody plants, whether native or not, should be removed to allow the open, sunny conditions required by the species. This should be done manually or with carefully timed and planned fire; chemical herbicides should be used only as a last resort. Herbicides are often used on roadsides to kill all broadleaf plants, thereby leaving only the non-native B. inermis. Since a large proportion of the surviving colonies of V. edulis var. ciliata occur on roadsides (because they are usually out-of-reach of the plow), this creates a double dilemma. Not only will the herbicides kill V. edulis var. ciliata, they will kill all broadleaf plants, removing nearly all competitors of B. inermis. This allows B. inermis to thrive and create such a dense sod that no broadleaf plant, including V. edulis var. ciliata, has a chance to get reestablished.

  Conservation Efforts in Minnesota

Several sites of this species occur on public land that was acquired for conservation purposes. However, proper and consistent management of these sites remains a challenge.

  References and Additional Information

Meyer, F. G. 1951. Valeriana in North America and the West Indies (Valerianaceae). Annals of the Missouri Botanical Garden 38(4):377-503.