Sempervivum arachnoideum, the cobweb house-leek, is a species of flowering plant in the family Crassulaceae, native to European mountains, in the Alps, Apennines and Carpathians. Growing to 8 cm tall by 30 cm wide, it is a rosette-forming succulent perennial, valued in cultivation for its ability to colonise hot, dry areas via offsets. The specific epithet arachnoideum refers to its furry central rosettes (long ciliate leaf margins), resembling spider webs. It flowers in July, with pink flowers that are raised on stems and are hermaphroditic (having both male and female organs). This plant, and the subspecies Sempervivum arachnoideum subsp. tomentosum, have gained the Royal Horticultural Society's Award of Garden Merit.
No narrative description available for this taxon yet.
⚠ sources differ — GIFT: 0.075 m · LEDA: 0.075 m · TRY: 0.138 m
Plant height generative0.1 m
Plant height max0.1 m
Plant height min0.04 m
Seed length0.52 mm
Seed mass0.028 mg
Life cycle & reproduction8
Deciduousnessevergreen
Dispersal typeself
Flowering endSep
Flowering startJul
Life formsucculent perennial
Life spanperennial
Lifespan years5 years
Raunkiær life formchamaephyte
Diet & foraging1
Parasiteindependent
Habitat & environment4
Climatetemperate
Climberself-supporting
Growth formshrub
Woodinessnon-woody
Physiology & chemistry1
Photosynthetic pathwayCAM
Other traits2
Diaspore typeseed
Plant support typefree-standing
03Chemical composition3 compounds
Compounds documented for Sempervivum arachnoideum across natural-product and food-composition databases — not just the ~150 nutrients on a classic label ("nutritional dark matter").
Compound class profile1 class
Flavonols3
Documented compounds3 total
Compound
Class
Amount
Source
Kaempferol
present
LOTUS
Myricetin
present
LOTUS
Quercetin
present
LOTUS
05DNA & barcoding1 specimens
A DNA barcode is a short, standardised stretch of genes that works like a fingerprint — enough to tell one species from another. Below is the molecular trace Sempervivum arachnoideum has left across the world's sequence archives.
At a glance
DNA specimens1
Marker genes2
GenBank sequences10
eDNA detections1
Countries1
The DNA barcodea real sequence read deposited for this species
★ the standard DNA barcode for this group — the short region actually read to tell this species apart. The rest are extra genes sequenced along the way.
★rbcL3★ITS7
plant barcodefungal barcode
06Genome at a glanceCCDB
The complete instruction manualSempervivum arachnoideum carries — its genome. We read it from three angles — how big it is, how the DNA is packed into chromosomes, and how completely it has been sequenced — and explain how to read each value as you go.
Chromosomes & ploidyhow the DNA is packaged
2n is the full chromosome count in a normal body cell; n is a gamete (egg or sperm), which carries half. Ploidy is how many complete chromosome sets each cell holds — 2× (diploid) is typical for animals, while higher levels (polyploidy) are common in plants. Click any value below to see the underlying records and sources.
CCDB · ita-fl — FAVARGER C. - 1972. Contribution l'tude cytotaxonomique de la flore des Apennins. I.. Bull. Soc. Neuchateloise Sci. Nat. , 95: 1/11/1934.
CCDB · ita-fl — Favarger C., Welter A. - 1979. Sur la prsence en Corse d'hybrides entre Sempervivum montanum L. et S. arachnoideum L.. Bull. Soc. Bot. Fr., Lettres Bot. , 126: 103-109.
CCDB · iber-fl — Nmeros cromosomticos de plantas occidentales, 38-45. Fernndez Casas, J. & A. Garca-Villaraco.Anales Jard. Bot. Madrid36: 395-397(1980).
CCDB · ipcn-api-dl — Favarger, C. & A. Welter. 1979. Sur la presence en Corse l'hybrides entre Sempervivum montanum L. et S. arachnoideum L. Bull. Soc. Bot. France 126: 103–109.
CCDB · ipcn-api-dl — Fernandez Casas, J. & A. Garcia-villaraco. 1980. Numeros cromosomaticos de plantas occidentales, 38-45. Anales Jard. Bot. Madrid 36: 395–398.
CCDB · CromoCat 2015 — Castroviejo & al. (2003). Flora Iberica (vol. I-VIII, X, XIV) Publicaciones del CSIC Madrid
CCDB · CromoCat 2015 — Fernández Casas, J. & García Villaraco, A. (1980). Números cromosomáticos de plantas occidentales, 38-45. Anales Jard. Bot. Madrid 36: 395-398.
2n 325×CCDB · fl-europaea · CCDB · CromoCat 2015
CCDB · fl-europaea — Zesiger, 1961
CCDB · CromoCat 2015 — Castroviejo & al. (2003). Flora Iberica (vol. I-VIII, X, XIV) Publicaciones del CSIC Madrid
CCDB · CromoCat 2015 — Welter, A. (1977). Étude d'un complexe polyploïde: Sempervivum arachnoideum L. (Crassulaceae) dans la flore orophile d'Europe centrale et meridionale. Thèse Universite scientifique et medicale de Grenoble. pp.90
CCDB · CromoCat 2015 — Welter, A. (1979). Étude d'un complexe polyploïde: Sempervivum arachnoideum L. (Crassulaceae) dans la flore orophile d'Europe centrale et meridionale. Compt. Rend. Hebd. Seances Acad. Sci., Sér. 288(4):387-390
CCDB · CromoCat 2015 — Welter, A. (1980). Study of a plyploid complex: Sempervirum arachnoideum L. in the mountain flora of Central and Southern Europe. Houslekes 11(2):51-55.
Human sightings and records, or camera-trap / sensor detections — someone (or a device) saw or captured the species in the wild.
Coordinate accuracy31% within 1 km
≤100 m 7 557≤1 km 1 789≤10 km 19 632>10 km 1 619
30 597 georeferenced · 6 317 without coordinates
Open the mapobservation + sensor36 914
Museum / Voucheredphysical evidence
Backed by a physical specimen — a herbarium sheet, sample or voucher held in a collection. “Vouchered” means supported by material evidence, not just an observation.
Coordinate accuracy32% within 1 km
≤100 m 14≤1 km 39≤10 km 105>10 km 6
164 georeferenced · 257 without coordinates
Open the institutions mapphysical evidence421
Cultivated / Captivenot free-living
A living individual in a botanical garden, zoo or nursery — cultivated or kept, not free-living.
Coordinate accuracy100% within 1 km
≤1 km 4
4 georeferenced · 7 without coordinates
Open the mapnot free-living11
Wildobservation + sensor
Human sightings and records, or camera-trap / sensor detections — someone (or a device) saw or captured the species in the wild.
10Collections & institutions
Holding institutions32 of 65 geolocated
Institutions and collections holding physical, vouchered specimens of this species — click a row to fly to it on the map.
Institution
Specimens
BIO-UNIPIlocation not on record
72
Bern, CH
25
Chicago, US
24
LDlocation not on record
24
Museum Ludovicae Ulricae, Zoology Institute of the University of Uppsalalocation not on record
22
BFLlocation not on record
17
MAlocation not on record
15
Oskarshamn, SE
15
Salzburg, AT
15
BDBClocation not on record
11
SLU Artdatabankenlocation not on record
9
BClocation not on record
9
Institut und Museum fuer Geologie und Palaeontologielocation not on record
8
Entomological Society of Latvialocation not on record
8
Bourges, FR
7
Philadelphia, US
6
CJBGlocation not on record
6
Glarus, CH
5
Porrentruy, CH
4
BRNUlocation not on record
4
Staatliches Museum fuer Naturkunde Karlsruhe (State Museum of Natural History)location not on record
4
Tilburg, NL
4
Paris, FR
4
GJOlocation not on record
4
Görlitz, DE
4
Barcelona, ES
4
St. Paul, US
4
Adam Mickiewicz University in Poznańlocation not on record
4
Provincia di Livornolocation not on record
3
Wlocation not on record
3
Uppsala, SE
3
MeiseBGlocation not on record
2
SNSNMClocation not on record
2
Madison, US
2
Canadian Department of Agriculturelocation not on record
2
Helsinki, FI
2
Vitoria, ES
2
College of the Atlantic, Museumlocation not on record
2
CICYTEXlocation not on record
2
Edinburgh, GB
1
Denver, US
1
Moscow State Universitylocation not on record
1
Salamanca, ES
1
Wellington, NZ
1
Zürich, CH
1
Museo civico di Storia naturale Giacomo Doria di Genova | Giacomo Doria Natural History Museum in Genoalocation not on record
1
Badajoz, ES
1
SZUlocation not on record
1
Rotorua, NZ
1
Muséum Henri Lecoqlocation not on record
1
Fribourg, CH
1
IPE-CSIClocation not on record
1
Uniwersytet Śląski w Katowicachlocation not on record
1
LfUlocation not on record
1
Saint Louis, US
1
DBF-NHMDlocation not on record
1
València, ES
1
Monastir, TN
1
PRClocation not on record
1
Chongqing Museumlocation not on record
1
Boise, US
1
Pamplona, ES
1
Madrid, ES
1
Universidad de Caldas (UCaldas)location not on record
1
Auckland, NZ
1
65 institutions · 389 of 421 vouchered records shown · 30 without an institution code
Cultivated / Captivenot free-living
A living individual in a botanical garden, zoo or nursery — cultivated or kept, not free-living.
09Environmental DNA1 detections
Where the DNA of Sempervivum arachnoideum was picked up in samples of water, soil or air — nobody saw the organism, only its DNA left behind. A trace is a clue that the species was near, not a confirmed sighting.
Signal
Detections DNA found1
Studies independent surveys1
Countries1
Signal confidence: weakweighed across independent studies, places & mapped detections
Where its DNA was found
0 of 1 detections have coordinates
Open the map1 country0
How strong is each trace?
DNA read depthRead counts were not reported for this species — the map shows presence only, not how strong each trace was.
Modelled climatemodelled
−15°Ctemperature across detection sites+40°C
Temperature median5.50 °C 5.50–5.50
Seasonal swing summer↔winter22.1 °C
Max temp (day)9.80 °C
Min temp (night)-0.5 °C
Precipitation81.3 mm/mo
Air humidity59.8 %
Moisture balance11.5 mm/mo
Vapour deficit411 Pa
Wind speed2.20 m/s
Cloud cover46.4 %
CHELSA 1981–2010, ~9 km grid, at location & month of 1 detection point · median with p10–p90 · reflects where sampling happened, not only the true niche
How to read this: each dot is one detection of this species' DNA in an environmental sample. The confidence meter weighs how many independent studies and places back up the signal — one detection in one study is a hint; many across several studies is solid. Records dated before 2008 (when eDNA methods began) are treated as likely mislabeled and left off the map.
WikipediaWikimedia Foundation11 languages↗
BioWikiNetmultilingual Wikipediamultilingual↗
GBIFGlobal Biodiversity Information Facility37 413 records↗
ENAEuropean Nucleotide Archive · EMBL-EBI1 eDNA detections↗
BOLD SystemsCentre for Biodiversity Genomics1 specimens↗
NCBIUS National Library of Medicinesequences↗
LOTUSNatural Products (Wikidata)compounds↗
GRIN TaxonomyUSDA-ARSdistribution & uses↗
Open Tree of LifeOpenTreephylogeny backbone↗
CCDBChromosome Counts DB · Tel Aviv U.genome & karyotype↗
PloiDBPloidy Databasegenome & karyotype
Paleobiology DatabasePBDB consortiumfossil record↗
GLoBIGlobal Biotic Interactionsbiotic interactions↗