Chaparral is the name of the ecoregion that extends from Baja Mexico to northern California along the coast and in towards the Sierra Mountains. The ecoregion gets its name from the Chaparral plant community, which is dominated by shrubs: Scrub oaks, Toyon (has red berries, looks like holly if you are in a hurry, and Hollywood gets its name from this plant), Sage, Coyotebush, Manzanita, Chamise, etc. - lots of plants that you would recognize if you happen to live in this part of the world. The name comes from the Spanish word "chaparro" meaning green oak. Chaparral is often pretty dense brush - them leather leggins that cowboys wear are "chaps" to protect their legs as they ride through. Great article about Chaparral at Wikipedia http://en.wikipedia.org/wiki/Chaparral .
There are other shrub-dominated plant communities that are part of the Chaparral ecoregion. Coastal sage scrub consists of California sagebrush (which is Artemisia, not Sage, Salvia as I had thought); also Coyotebush and Lupine. This is the plant community that dominates the Marin Headlands where it looks common enough. So much urban development has taken place along the coast, however, that Coastal sage scrub may be an endangered habitat type. Las Pilitas Nursery has a great run down on this plant community and its plants http://www.laspilitas.com/nature-of-california/communities/coastal-sage-scrub
The Chaparral ecoregion also includes tree-dominated plant communities, some of which don’t at all look like the Chaparral plant community, so this is a bit confusing till you see these plant communities out in the field in great interdigitated swaths. I spent much of today hiking through 200 acres of Central Oak Woodland plant community which transitioned to Chaparral, and both of which descended to a riparian plant community at the valley bottoms (in Mendocino County, California, USA).
Although aspect plays a part in plant community dynamics it is relatively minor. For example a north-facing (cool) slope Chaparral community might have more Toyon and Oak while a south-facing (hot) slope also has Chaparral, though you might find more Chamise. Far more important is the depth of soils. Shallow soils – Chaparral. Deeper soils – Central Oak Woodland dominated by Blue oak, much deeper soils - Central Oak Woodland dominated by Black Oak, which drops a lot of leaf litter and as a consequence builds up an even deeper soil. It is no accident that some of the best vineyard terroirs in Napa, Sonoma, and Mendocino Counties are on sloping sites that used to be Black Oak stands.
