Listmania!
So. Calif. plant identification
By an Amazon.com customer
A Flora of Southern CaliforniaA Flora of Southern California by Philip A. Munz
Buy used from: $34.00
Without doubt, the best reference for this area. Find a used one if it's out of print. Key plants here, then verify if needed with illustrations in other books.
The Jepson Manual: Higher Plants of CaliforniaThe Jepson Manual: Higher Plants of California
Buy new: $83.05 / Used from: $45.89
A good reference, but suffers from a few serious flaws. Got a little space, so 'll say here that I have little use for wildflower guides. You need a comprehensive flora to ID plants.
A Flora of San Diego County CaliforniaA Flora of San Diego County California by R. Mitchel Beauchamp
Buy used from: $40.00
Handy field size. More widely useful than you might expect, especially in Riverside, Orange, and Imperial Cos. (not comprehensive there, but good for quick ref.). Keys but no illustrations.
Flora of Santa Cruz IslandFlora of Santa Cruz Island by Steve Junak
Buy used from: $97.00
A beautiful book with keys and tons of great illustrations. Useful on the adjacent mainland too (see caveat above).
Intermountain Flora Vol. 6: The MonocotyledonsIntermountain Flora Vol. 6: The Monocotyledons by Arthur Cronquist
Buy used from: $183.44
All vols. are excellent. I list V. 6 because grasses & sedges are so hard. Fully illustrated. Esp. good for N & E Mojave & adj. mts. I want something like it for Calif! Awaiting publ of last volume.
Illustrated Flora of the Pacific States (4 Vol. Set)Illustrated Flora of the Pacific States (4 Vol. Set) by Leroy Abrams
Buy used from: $100.18
A huge effort done very well. Exhaustive, with an illustration for every plant. Illustrations often too small, but there's just nothing else like it anywhere. You'll need it eventually.
Vegetation and Flora of the Sonoran DesertVegetation and Flora of the Sonoran Desert by Forrest Shreve
Buy new: $185.00 / Used from: $52.88
Exhaustive and essential for the low desert. Sorry, no illustrations.
A Flora of the Marshes of CaliforniaA Flora of the Marshes of California by Herbert L. Mason
Buy used from: $115.00
Fantistic, wonderfully illustrated book. Essential for wetlands identifications. Far better and more complete than the photocopied wetland guidebooks.