Synonyms

Lycopodium porophilum, Huperzia selago var. porophila, Lycopodium selago var. patens

  Basis for Listing

This fern ally appears to have several discontinuous ranges. The northern range includes parts of the upper Midwest, and the southern range is centered in the mountainous regions of the east-central states. Within these ranges, Huperzia porophila may be locally common in moist, sheltered habitats on sandstone ledges. However, the species seems to be rare even where suitable habitat exists. Historic populations documented by herbarium specimens collected in Blue Earth County in 1883, in Hennepin County in 1902, in Lake County in 1943, and in St. Louis County in 1949 have presumably been destroyed by human activities. There are only a very few populations known to currently exist in Winona, Houston, Cook, and Lake counties. Given its rarity, Huperzia porophila was listed as a threatened species in Minnesota in 1984.

  Description

The genus Huperzia in Minnesota consists of 4 species: H. porophila, H. lucidula (shining fir moss), H. appalachiana (Appalachian fir moss), and H. selago (northern fir moss), and a wide assortment of their hybrids. They all have sporangia borne in the axils of unmodified leaves rather than in strobili or "cones." Huperzia porophila can be distinguished from the other 3 species by its short, slender rooting bases (as compared to the sprawling and elongate bases of H. lucidula) and flat leaf bases (as compared to the plump, hollow leaf bases of H. selago). However, positive identification usually requires a microscopic examination of the spores.

  Habitat

Prior to 2000, all Minnesota specimens had been collected from sandstone bluffs and ledges in southeastern Minnesota. Beginning in 2000, the species was found at a number of sites in northeastern Minnesota on diabase cliffs. Sites in the northeast are typically northerly facing, wooded habitats that are moist and well shaded. Throughout its Minnesota range, H. porophila occurs with other Huperzia species and hybrids, especially H. lucidula, H. appalachiana, H. x bartleyi (Bartley's fir moss), and H. x buttersii (Butters' fir moss). Typically, H. porophila is much less abundant than other Huperzias at a given site.

  Biology / Life History

Vegetative growth begins in the spring or early summer, and spores are produced in mid- to late summer. Like most other Minnesota Huperzias, the foliage is at least somewhat evergreen. Plants often reproduce vegetatively through gemmae, which break off from the upper portions of the plant to form new plants. Hybrids are common, and are often found in mixed populations with H. lucidula, H. selago, H. appalachiana, and H. porophila.

Plants are visible throughout the growing season, but because spores are needed for positive identification, searches for H. porophila should be conducted from mid-summer through fall.

  Conservation / Management

Habitat for H. porophila is limited in Minnesota. Potentially suitable habitats can be found only in the Lower Mississippi and Minnesota River valleys and in scattered sites in the Arrowhead region. But even where suitable habitat is available, H. porophila rarely occurs. The two historic populations known from old herbarium specimens (Blue Earth County in 1883 and Hennepin County in 1902) have never been relocated and may no longer exist. However, because of the resemblance of this species to more common Huperzia species and hybrids, and its propensity to grow in mixed colonies, some populations may have been inadvertently overlooked. Targeted searches in regions of the southeast where sandstone bedrock occurs at the surface, and diabase cliffs in the northeast, may uncover new populations.

Even though the cliff habitats of this species might seem durable and not easily damaged, the rare plant assemblages that occur on them are extremely fragile. They are shallowly rooted in crevices and typically occur in low numbers. Huperzia porophila occurrences warrant protection from recreational uses such as rock-climbing and scrambling (non-technical rock hopping and exploration).

  Conservation Efforts in Minnesota

Known populations of H. porophila currently exist in a State Park, a State Forest, and on the property of a private environmental learning center. These sites are presumably well protected from most development activities that might threaten this species, such as rock quarrying, but the subtler threats posed by recreational use of cliff habitats have not been fully addressed.

  References and Additional Information

Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis, Minnesota. 320 pp.

Peck, J. H. 1982. Ferns and fern allies of the driftless area of Illinois, Iowa, Minnesota, and Wisconsin. Milwaukee Public Museum Press, Contributions in Biology and Geology Book 53, Milwaukee, Wisconsin. 140 pp.

Wagner, W. H., Jr., and J. M. Beitel. 1993. Huperzia. Pages 20-24 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 2. Oxford University Press, New York, New York.