A remarkable low growing species with silver/grey leaves and black, honey-scented flowers. It is hardy enough to be grown outside in the southern UK, given a sunny, sheltered, freely drained spot. In 2010 it lost its leaves but came back as strongly as ever to flower late summer and autumn.
It seems most of the 'sidoides' in cultivation in the UK are hybrids (probably with P.reniforme) and have wine purple/maroon flowers. The easy way to tell is that the hybrids have main stems and make a bushy plant much like many popular 'scented leaved' pelargoniums with the flowers on side branches.
Sidoides on the other hand has no stems at all - the leaves are on long petioles arising directly from the base of the plant. The flowers are on very long (up 40cms), extremely slender stems which also arise directly from the base and radiate out horizontally. The flowers are very close to true black with no hint of purple or pink. Once you have seen the two together the difference is obvious.