Salvia x jamensis plants are a cross between Salvia microphylla and Salvia greggii, with massed flowers similar to those of their parents. They are proving to be excellent compact salvias for Sydney, blooming over a long period from late spring till autumn. The two species share native territory in northern Mexico near the village of Jame (pronounced 'ha-may') in the province of Coahuila and hybridised naturally to produce plants known colloquially as 'Jame sage', which were discovered in 1991. Plants have also been found in a couple of other nearby provinces in Mexico. They form shrubs usually less than a metre in height and flower colours range from red, rose and orange to salmon and pale yellow; some are bicoloured.
In horticulture, any complex hybrid involving these two species is also called Salvia x jamensis, and recent years have seen the appearance of many named cultivars. In my experience, they do better in Sydney than the Salvia greggii cultivars, which seem to prefer less humidity. A well-known example of Salvia x jamensis is the plant 'Hot Lips' (pictured above, ht 90 cm), a vigorous, bushy perennial, with bicoloured red and white flowers (although in very hot weather, the colour can vary to all-white or all-red!). My understanding is that the 'Mesa' range of Salvia are also Salvia x jamensis. They are very good plants and come in a range of colours. My favourite is 'Mesa Azure', which is a lovely soft blue/mauve hue, but there are also rose, purple and scarlet varieties. They grow to around 50 cm in height. The 'So Cool' and 'Heatwave' ranges, with flowers in many hues, may also be forms of this hybrid, although they are marketed as 'Salvia microphylla hybrids'.
Salvia x jamensis prefer sun (though will tolerate light shade) and good drainage. The best time to prune them in Sydney seems to be in late May. They will regrow through winter and begin to flower again in late spring, and will continue on until the end of autumn. Propagation is by cuttings or layering of stems.