Ssp.assurgentiflora comes from the northern Channel islands (Anacapa and San Miguel), and Ssp. glabra from San Clemente and Santa Catalina islands.
Historical Reference: Lavatera assurgentiflora is a large shrub, sometimes twelve feet tall, from the Santa Barbara Channel Islands. Some say it came originally from Spain. At any rate it is growing on the Islands and since it has been used for a long time for coastal windbreaks it has escaped bounds and naturalized itself near the coast almost as far north as San Francisco. This Island Mallow is a valiant battler with the elements and a courageous bloomer. In spring it is gay with flowers; when Foxtail and other grasses turn loose their seeds to bristle like porcupine quills in collectors' and photographers' clothing, it is still alive with rose-pink, dark-veined bowls; when most wild shrubs are overtaken by drought and relax into rest, there are usually a few blooms left on the Mallow. It is only when the cold January winds thrash it about that L. assurgentiflora begins to look depressed, sheds some tattered leaves, and shows empty gray-green calyx cups hanging raggedly along its smooth, gray-tan boughs.
The big bush is rounded in shape but loose and open with many stems spreading outward from the base. The Maple-like leaves are a bright light green and the large bowl-shaped flowers, two inches across, are rosy pink, a little paler toward the center, and striped with deep purple-carmine, suggesting in their detail an old flower picture.
If you live along the California coast south of San Francisco or in a corresponding coastal climate elsewhere you can hardly fail with Lavatera assurgentiflora and you will find it very useful for a wide hedge in poor soil where few other shrubs will grow. As it will volunteer all over the place, you may expect to see a whole forest of little Mallows. A bit of pruning helps it to keep its shape, but summer watering is not absolutely necessary. I bave never tried growing it in northern coastal California nor in gardens of the hot, dry, sections of the interior.
Flowering Shrubs of California and Their Value to the Gardener
By Lester Rowntree
Stanford University Press, first edition 1939