Phil Savoie / Smeathman's furrow bee (Lasioglossum smeathmanellum) tiny bee feeding on Biting stonecrop (Sedum acre) Monmouthshire, Wales, UK. June.

Phil Savoie / Hairy yellow faced bee Hylaeus hyalinatus), female, feeding on Biting stonecrop ((Sedum acre) flower, Monmouthshire, Wales, UK. June.

Phil Savoie / Hairy yellow faced bee Hylaeus hyalinatus), female, feeding on Biting stonecrop ((Sedum acre) flower, Monmouthshire, Wales, UK. June.

Dong Lei / Rhodiola crenulata growing in mountain habitat, Mt Qomolangma National Park, Qinghai Tibet Plateau, China.

Dong Lei / Rhodiola crenulata in mountain habitat, Mt Qomolangma National Park, Qinghai Tibet Plateau, China.

Dong Lei / Rhodiola crenulata, Mt Everest, Mt Qomolangma National Park, Qinghai Tibet Plateau, China.

Heather Angel / Mother of thousands (Kalanchoe daigremontiana), viviparous growth with vegetative propagation of plantlets on leaf margins. In cultivation.

Nick Upton / Dark purple tree houseleek (Aeonium arboreum atropurpureum), a Moroccan species, flowering, Jardin de Cactus, Lanzarote, Canary Islands, February.

Nick Upton / White Stonecrop (Sedum album) clump flowering in a limestone rock crevice, near Sotres, Picos de Europa, Asturias, Spain, August.

Nick Upton / White Stonecrop (Sedum album) clump flowering in a limestone rock crevice, near Sotres, Picos de Europa, Asturias, Spain, August.

Ernie Janes / Lamb's-tail flowers (Umbilicus oppositifolius) Norfolk, England, UK. May.

Ernie Janes / Glaucous echeveria (Echeveria secunda var. glauca) cultivated plant native to Mexico.