Does your wife mean 'Salix'? If your tree is a weeping one, which drops its leaves in winter, and then has catkin yellow flowers in spring, it'll be Kilmarnock Willow (willow is the common name for Salix)

I could find no reference to "salus" it could be a local name, the most common tree Ican think of is the Laburnum or a shrub such as forsythia.
You could put yellow flowered tree into google images and then show them to your wife, if we have a name we may be able to help