Huperzia selago (Lycopodium selago) (s.lat); The Fir Clubmoss has a characteristic fingerlike growth of stems branching form the base. The vegetative leaves and sporophyl-bearing leaves are similar. Thus the plant does not have a sporohpyllic cone like most other clubmosses. Quite characteristic are also the presence of gemmae (sometimes referred to as bullbills). The absence of trailing stems ("runners") is also a characteristic that can be used to identify this primitive tracheophyte on Iceland. It grows in heatherlands and amongst rocky places. On Iceland it is generally known as Skollafingur.
Huperzia's make up a complicated group where the species defenition still has to be settled by specialists. The description above is a general one. There are though rather distinct growth types (morphotypes) which are considered to be different species by some specialists where others consider the three groups on Iceland as subspecies of the the species H. selago. On top of that in different regions of the (sub-)arctic of the northern hemisphere hybrids are found. The three groups are:
- "appressa": These plants have leaves at the bottom which are larger than those on top. It forms gemmae* along the upper part of the stem. The leaves are spreading below but pressed to the stem in the middle and top part of the stem).
- "arctica": leaves are equal below and above. Gemmae* are only formed on the top. The leaves are pressed to the stem except where gemmae had been formed in the past, giving the plant a rather shaggy appearance. They form sporangia all along the stem.
- "selago s.str.": These plants rarely form gemmae*. They have sporangia's only in the distal (top) part of the stem. The leaves are all spreading. Populations of this morphotype are found only in the lowlands.
All three morphological types grow on Iceland. However, some consider appressa and arctica as one morphological type, being arctica. Populations of this/these morphotypes are more common, both in low- and highlands
*: Gemmae: a gemma is a vegetative reproduction product. These can vary from a few-celled rod (common in mosses) to a a group of small leaves as seen in this species(-group). See the photo to get an impression.
So one can goup them as three subspecies of Huperzia selago (Huperzio selago subsp. selago, Huperzia selago subsp. appressa and Huperzia selago subsp. arctica) or as three different species (Huperzia selago s.str, Huperzia appressa and Huperzia arctica
the Icelandic names to these three groups are:
- selago s.str.: Skollafingur
- appressa: Paufafingur
- arctica: Skufsafingur
They are all members of the Lycopodiaceae, the clubmoss family