How many different plants are there in LA County? No one knows!
One thing I've found difficult in trying to photograph all the plant taxa that are native to LA County is that there is no master list. The closest thing I could find was doing a Calflora.org search for native plants by county. This usually results in about 3000 to 3300 plants, depending on updates. There are a couple problems with this number:
Some ID's end up in the wrong places but are still included in the search. I found many observations from the High Sierras showing up as being in Beverly Hills.
Herbarium vouchers are marked as occurring where the physical herbarium building is located instead of where the plant was actually collected.
Having a list of plants is pretty important to the project so I went through all the Calflora IDs to see what actually occurs in LA County. I ended up with 2,590 unique plant taxa in our little zone after excluding plants relevant to the above two problems. If a person said they collected/observed a plant in LA County in the description, then I included the plant.
2,590 plants is an extremely high level of biodiversity. For context, the California Floristic Province in total has 6,927 plants over 293,803 sq km . In LA County, we have 2,590 over just 12,310 sq km . The CFP has 0.0235 plant taxa per sq km on average while LA County has 0.2104. So LA County has nearly 10x higher levels of plant biodiversity than the average level for a world biodiversity hotspot, pretty impressive.
Here is Draft 1 the list, please reach out with any corrections.