Houseleeks

A couple weeks ago I blethered a bit about my replanting of a pot formerly dedicated to annuals with an assortment of stonecrops (sedums) and a houseleek. When I first got to blethering I hadn't taken the time to read the plant tags closely (probably a mistake which I will live to regret, but gardeners are all about hope. In my defence I'll note that Homestead had -- and has had -- an established container planting of mixed sedums and what-have-yous, in which I can identify all the things I got, so I don't think I'm being too over-optimistic).

When I got around to reading the plant tags, I found that I'd managed to go on a world tour of stonecrops -- the genus is distributed throughout the northern hemisphere, and the selection I brought home includes natives to places ranging from Europe to Siberia.

Then I looked at the tag for the houseleek, which was labelled 'hens and chicks' in big letters across the top. I saw it was also labelled (in much smaller print), Echeveria nodulosa.

That's funny, thought I. I thought houseleeks were Sempervivum spp.

So then I started reading, and oh, the things I have learned.

First off, all three genera -- Echeveria, Sedum, and Sempervivum -- belong to the family Crassulaceae, so they're cousins and kin. Most of them are succulents. In growth habit, they can range from creepers to shrubs. I am going to ignore the genus Jovibarba which is very closely related to Sempervivum, and sometimes considered a subgenus of it, because I don't want to get bogged down there.

Houseleeks, also called Hens and Chicks, are Sempervivum, usually S. tectorum though there are other species. They're also sometimes called by names which seem to reflect the belief that they dispelled lightning, such as Jove's beard or Thor's beard. They're native to southern/central Europe but have long since been spread to the rest of the continent. Sempervivophilia offers a survey of houseleeks and man from the classical period onward.

That Charlemagne ordered houseleeks planted on the roofs of houses to dispel lightning was engraved somewhere deep in my brain, and apparently deep in the brains of garden writers everywhere, but I couldn't find the source at first and was beginning to wonder if we'd all been taken in by some superb urban legend.

Not so. Charlemagne's edict is found in his Capitulare de villis, LXX: Et ille hortulanus habeat super domum suam Iovis barbam.

Note though that while the houseleeks are called 'Jove's beard' (the common name for them in French is still 'joubarbe') the edict doesn't specifically mention lightning. So where'd the lightning part come from? Did folk belief get tacked on somewhere?

Sempervivophilia also notes that there are no classical references to houseleek as a dispeller of lightning.

However.

Linnaeus is said to have mentioned the use of houseleek was a means of preserving thatched roofs from fire; I've traced this reference in English so far as the second edition of Elizabeth Kent's Flora Domestica (1825). The Uppsala University Linnaeus garden tour site mentions that in Linnaeus's home province of Småland, common houseleek was planted on the roofs as a protection against fire.

The advantage of a thatched or turf roof planted with succulents over one not so planted seems clear enough. Sempervivophilia has a photo of houseleeks after a fire, where they seem to have been the only thing that survived.

I am unclear as to the nature of Linnaeus' references to houseleeks. The first time I encountered the reference to him, he was presented as being 'astonished' at the habit of Swedes for covering their roofs with the plants. It seems unlikely that he'd have been too astonished if it was common practice in the province where he was born and raised, unless perhaps his astonishment dated from his first exposure to the practice as a young boy. I haven't tracked down the exact reference yet so I can't say for sure.

A last note on houseleeks: the (British) Natural History Museum research project on country cures includes a page on the houseleek.

Now, what of my echeveria?

Echeverias are also commonly called hens and chicks, and they are similar in appearance and habit to houseleeks. The echeverias, however, are native to central America. The genus is named after the 18th C. botanical artist Atanasio Echeverría y Godoy (mispelled on approximately a bazillion web sites as Echeverria Codoy). Little seems to be known about Echeverría, other than that he accompanied Martin de Sessé y Lacasta and Mariano Mociño Suárez de Figueroa on their expedition to document the flora and fauna of Mexico. Some of his drawings survive in the collection of the Hunt Institute.

My plant I think was mislabeled, or at least it looks nothing like E. nodulosa. It looks more like the pictures I've googled of E. runyonii var 'Topsy Turvy.'

No word yet on echeveria as a defence against fire or lightning. Given that my house has survived probable hundreds of thunderstorms since it was built, there is probably nothing very surprising in it surviving the several which have passed through since I planted the echeveria.