A reader with an interest in C4 plants

"Hi, I was wondering if you could tell me a big list of all the flowering plants that use c4 photosynthesis. also which ones are available in Washignton state during the fall season."

For those of you who don't know C4 plants have an alternative photosynthetic system where the 1st product of photosynthesis if a 4-carbon molecule, thus C4. The great advantage over "regular" C3 photosynthesis is that carbon fixed isn't lost to photorespiration, which increases at higher temperatures.
So let's pull out our big list of Washington state plants that use C4. Oops, well, no such list exists. Without knowing the reason for this query, it's hard to offer much direction. C4 plants should be easy to find, even during the fall, but C4 crops may be in seasonal decline. Here's the easy ones, most of which can be found in WA, all tropical grasses: maize, sugarcane, sorghum, also switch grass and Bremuda grass. A lot of desert plants are C4, but not sure how hot and dry Washington state deserts are. If native plants are sought, then best check with the WA Native Plant Society.