Sempervivum arachnoideum

{{Short description|Species of succulent}}

{{Speciesbox

|image = Sempervivum_arachnoideum.jpg

|genus = Sempervivum

|species = arachnoideum

|authority = L.

}}

Sempervivum arachnoideum, the cobweb house-leek,{{BSBI 2007 |accessdate=2014-10-17 }} is a species of flowering plant in the family Crassulaceae, native to European mountains, in the Alps, Apennines and Carpathians. Growing to {{convert|8|cm|0|abbr=on}} tall by {{convert|30|cm|0|abbr=on}} wide, it is a rosette-forming succulent perennial, valued in cultivation for its ability to colonise hot, dry areas via offsets.{{cite book|title=RHS A-Z encyclopedia of garden plants|year=2008|publisher=Dorling Kindersley|location=United Kingdom|isbn=978-1405332965|pages=1136}}

The specific epithet arachnoideum refers to its furry central rosettes (long ciliate leaf margins), resembling spider webs.{{cite book|last=Harrison|first=Lorraine|title=RHS Latin for gardeners|year=2012|publisher=Mitchell Beazley|location=United Kingdom|isbn=9781845337315|pages=224}}

It flowers in July, with pink flowers that are raised on stems and are hermaphroditic (having both male and female organs).

This plant,{{cite web|title=RHS Plant Selector - Sempervivum arachnoideum|url=https://www.rhs.org.uk/Plants/17075/Sempervivum-arachnoideum/Details | access-date = 5 March 2021}} and the subspecies Sempervivum arachnoideum subsp. tomentosum,{{cite web | url = https://www.rhs.org.uk/Plants/44689/Sempervivum-arachnoideum-L-subsp-tomentosum-(C-B-Lehm-Schnittsp-)-Schinz-Thell/Details | title = RHS Plantfinder - Sempervivum arachnoideum subsp. tomentosum | access-date = 9 November 2018}} have gained the Royal Horticultural Society's Award of Garden Merit.{{cite web | url = https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants - Ornamental | date = July 2017 | page = 96 | publisher = Royal Horticultural Society | accessdate = 9 November 2018}}