Rare Species Guide

  Synonyms

Salicornia europaea ssp. rubra

  Basis for Listing

Salicornia rubra (red saltwort) is a succulent halophyte characteristic of salt flats and the margins of alkaline lakes in arid regions of the West. The range of S. rubra is relatively widespread, but because of its specialized habitat, its distribution is local and sporadic. The occurrence of S. rubra in Minnesota seems incongruous, because its habitat is not widely known to occur in the state. Such habitats do exist at the western edge of Minnesota, but they have always been uncommon and have now been largely eliminated by agricultural activities.

There are very few documented records of S. rubra in Minnesota, most of which are from Kittson County (Aspen Parklands Subsection) at the far northwestern corner of the state. Some of these records have not been verified on the ground for several years and may no longer be extant. Kittson County is the only county in Minnesota where a significant amount of suitable habitat may still exist. And yet, land conversion for agriculture continues to proceed at a rapid rate. Much of this land was previously considered unsuitable for agriculture because of its low productivity. But because of the high demand for land, the conversion of marginal land is expected to continue. For these reasons, S. rubra was listed as a threatened species in Minnesota in 1984.

There have recently been reports of S. rubra occurring on gravel shoulders of freeways in the Twin Cities metro area. This is not surprising. The heavy use of salt on freeways in the winter and the periodic grading of the shoulders create marginal habitat for S. rubra. It is likely that seeds of this species were inadvertently carried to these habitats by road maintenance equipment that had previously been used in western states. These roadside occurrences of S. rubra are clearly transitory and are not considered viable populations. As such, they have no role to play in conservation. If S. rubra is to survive in Minnesota, it must be preserved in its native habitat.

  Description

Among Minnesota's flora, the appearance of S. rubra is quite unusual and distinctive. It has succulent, apparently leafless stems and branches, producing a skeleton-like appearance. The flowers are very small and appear to come from joints in the stem (actually rudimentary leaves). They will not be noticed without a close examination of the plant. At maturity, the whole plant turns ruby red, creating the impression of a red carpet around pond margins where it occurs. Nothing about the plant will appear at all familiar to someone who is not familiar with the genus (Kadereit et al. 2007).

  Habitat

Salicornia rubra occurs in salt flats, alkaline depressions, exposed shores of alkaline lakes, and saline swales in prairies. Suitable habitats receive full sunlight and are sparsely vegetated. When evaporation at a site exceeds inflow of water, soluble salts and exchangeable sodium may accumulate, resulting in alkaline or saline soils. These salts or sodium can be found naturally in the soil, in soluble fertilizer salts, in stream water, lake water, or irrigation water. Such habitats are found sparingly in western Minnesota. Associated plant species that are also tolerant of these extreme conditions include Atriplex patula (spearscale), Distichlis spicata var. stricta (salt grass), Hordeum jubatum (foxtail barley), Puccinellia nuttalliana (Nuttall's alkali grass), and Suaeda calceoliformis (sea-blite).

  Biology / Life History

Salicornia rubra is a small annual forb with succulent stems. It shows an unrivaled tolerance for saline conditions. In fact, it has been shown to require high concentrations of salt (NaCl) rather than simply tolerating it (Tiku 2006). Plants become shorter and denser at higher salinity but are not significantly harmed. As a wetland dries or water levels recede, the seeds of this species will germinate in the exposed salt or alkali-encrusted silt.

Vegetation zones in such habitats vary markedly from year to year depending on water levels. These are pioneer communities that may be dominated by only a few specialized species or sometimes only S. rubra. Salicornia rubra has been observed to cover an entire wetland basin in exceptionally dry years when little, if any, standing water remained by late summer. Such productive years serves to replenish a seed bank in the soil that can persist until favorable conditions return (Gul and Weber 2001). The seeds have the ability to maintain viability even under the most saline conditions (Khan et al. 2001).

  Conservation / Management

Because native habitats on saline and alkaline soils that S. rubra prefers have been largely eliminated by agricultural activities, it is very important to protect any remaining habitats from degradation. Wetland protection laws that prevent draining or filling are vital in this regard.

  Best Time to Search

The best time to search for Salicornia rubra is when plants have matured, though neither flowers nor seeds are needed for identification. At maturity, the stems will have turned scarlet and be easily visible. This is generally late summer into autumn but may be weather dependent.

  Conservation Efforts in Minnesota

What is believed to be the largest and most stable population of S. rubra in Minnesota occurs at Salt Lake Wildlife Management Area in Lac Qui Parle County (Minnesota River Prairie Subsection). The population there is large, well-protected, and presumably viable. Other known sites are smaller, unprotected, and vulnerable.

  Authors/Revisions

Welby R. Smith (MNDNR), 2021

(Note: all content ©MNDNR)

  References and Additional Information

Gul, B., and D. J. Weber. 2001. Seed bank dynamics in a Great Basin salt playa. Journal of Arid Environments 49(4):785-794.

Harris, L. C., B. Gul, M. A. Kahn, L. D. Hansen, and B. N. Smith. 2001. Seasonal changes in respiration of halophytes in salt playas in the Great Basin, U.S.A. Wetlands Ecology and Management 9:463-468.

Kadereit, G., P. Ball, S. Beer, L. Mucina, D. Sokoloff, P. Teege, A. E. Yaprak, and H. Freitag. 2007. A taxonomic nightmare comes true: phylogeny and biogeography of glassworts (Salicornia L., Chenopodiaceae). Taxon 56(4):1143-1170.

Khan, M. A., B. Gul, and D. J. Weber. 2000. Germination responses of Salicornia rubra to temperature and salinity. Journal of Arid Environments 45(3):207-214.

Khan, M. A., B. Gul, and D. J. Weber. 2001. Effect of salinity on the growth and ion content of Salicornia rubra. Communications in Soil Science and Plant Analysis 32:2965-2977.

Tiku, B. L. 2006. Effect of salinity on the photosynthesis of the halophyte Salicornia rubra and Distichlis stricta. Physiologia Plantarum 37(1):23-28.