Endophyllum sempervivi - Parasite or Symbiotic Housleek's Rust?

As the name shows, it grows inside houseleeks leaves. In the genus Endophyllum there are about 15 parasitic species, everyone with its specific host. It belongs to the family Pucciniaceae (Basidiomycetes), where we find more common rusts (e.g. wheat rust or corn smut.) E. sempervivi is specialised only in houseleeks.

Unidentified rust on houseleek, similar to Endophyllum but with black spores. Bohinj, September.

After infection, visual damage is not immediately seen. Infected leaves then start growing to enormous sizes, up to 4 times the normal. The phenomenon can be explained as a changed concentration of growing enzymes (auxins).  Infected and prolonged leaves live long enough to supply the fungus with food. The rust doesn't destroy its host. At the end of its growing cycle, yellow-brown spores are observable on both sides of houseleek's leaves.

Gigantic form of houseleek. Bohinj, July.

A Blazing Forma - Another Unexplained Phenomenon

Here and there, in nature or in the culture, some rosettes are seen that are extremely asymmetrical. The leaves on the North side of the plant are much longer and erect. The plant seems to be turning to the sun. The phenomenon does not last, however, and extended consequences are not observed.

A blazing forma. Smokus"ki vrh, July.

For the Next Millennium

We are lucky to live in a country where habitat borders of houseleeks are concentrated. In Slovenia there is a SE border for S. tectorum, South border for S. wulfenii and J. globifera. Populations of species on their borders are always different from the majority, so some new forms could be found. We might recognise some other species in that territory which was neglected, (e.g. S. marmoreum forma dinaricum, S. montanum subsp. montanum, S. montanum subsp. stiriacum.) Even if no new forms are found or recognised, new field studies about houseleeks will increase the knowledge of this interesting genus. Precise distribution of these plants in our country is insufficient at this time. The plant's use might have a great future in food production too. It could be a natural food additive to prevent spoiling. There are many substances still to be discovered for medicinal use, and houseleeks definitely have effective contributions to make in that area.