Parish's bush-mallow (Malacothamnus parishii) is known only from its type collections from July 20th 1895 in the vicinity of San Bernadino, CA at an altitude of 1000-1500ft. It is presumed extinct as it hasn't been recorded since then and as the majority of the San Bernadino area is now developed.

This may be a distinct taxon or it may just be a form of the common Malacothamnus fasciculatus. The main distinguishing characteristic from Malacothamnus fasciculatus is the leaf shape being not very lobed and having parallel sides. The red lines denote this in the following image of a type specimen. (Update: I think the leaf bases being cuneate and not cordate may be a major thing to look for too.)

Below are scans of two type specimens:

Larger version here).

Larger version here).

As with all bush-mallows, relatively recent burn areas are the best place to look. Here is a map of recent burns in the San Bernadino area. Follow this link for an interactive map.

Here is a list of all collections from the same collector and day. All I can deduce from this is that he visited a wet area that day, but the Malacothamnus might not be from the wet area. If the collection numbers are in order, there is a fire follower in-between wetland taxa, so these may all be from near the same area. The Malacothamnus collection is flanked by dry-land taxa.

See also my post here on what to focus on if you want to be able to ID a bush-mallow from photos.