Eat pines, not pills!
While this list focuses on the leaves of conifers, vitamin C is also concentrated in the inner bark of many species (for example, eastern white pine inner bark at 100g contains approximately 200mg of vitamin C).
Vitamin C is prevalent year-round, though there is a trend of increasing content during the growing season for many conifers, with levels typically reaching their highest in the autumn months.
How do you prefer to get your vitamin C?
*Sources for this list include Journal of Ethnobiology and Ethnomedicine (2009), Canadian Medical Association Journal (1943), and Farmacia (2013).