Ivesia species are little known relatives of Potentilla known by the common name 'Mousetail'.
In general they are tap rooted herbaceous perennials, with many pilose, slender, fern-like leaves 3-18 inches long, sprouting from the base. These basal leaves are in some held upright in others loosely sprawling. The leaves have tiny lateral leaflets crowded in pairs along the leaf rib. These flexible slender leaves, with their densely packed overlapping leaflets can really look like mouse tails. Especially in the species Ivesia santolinoides. http://calphotos.berkeley.edu/cgi/img_query?enlarge=0000+0000+0709+1370
The flowers are, in many of the thirty species, clustered at the top of slender stems held just above the foliage in others they splay out around the crown. The hues of color range from white to bright yellow.
Most of the thirty species are found in far western states of OR, CA, NV, UT, ID, WA, CO, MT and AZ. Many have very limited distribution and therefore, concern is often voiced about the danger posed by developmental impacts on their ranges. The species occupy varied ecosystems from high alpine granitic screes and rock crevices, to vernally moist clay tables and ephemeral playas.
Miniature alpine and desert species would make good trough plants just for their unique foliage alone. Some of these include Ivesia rhypara, baileyi, webberi, cryptocaulis, pityocharis, longibracteata, lycopodioides, argyrocoma. The taller alpine and sub-alpine species hold their own in a larger rock garden setting with frilly foliage and nice airy displays of flowers. You may want to look for Ivesia tweedyi, gordonii, aperta or paniculata.
I grow Ivesia aperta var. canina, a rare variety found only in one valley of California. This Ivesia is known by the common name 'Dog Valley Ivesia' the valley is located in, Sierra County CA.
Ivesia gordonii is the most wide spread of the genus and is found at high elevations throughout the west. It is also one of the showest.