Abstract
The number of flowers of Sternbergia colchiciflora observed in autumn in its sole French locality is very variable from one year to another ; some years no flower is observed. Individual survey of plants in the field and cultivation ex situ show that even when no flower is observed, some plants produce fruit and seeds. Indeed, Sternbergia colchiciflora really flowers every year, but with two types of flowers, either chasmogamous, aerial and visible, or cleistogamous, subterranean and invisible. The ratio of these two types seems to depend, for the populations studied, on the amount of rainfall in September, a high amount favouring chasmogamy to the detriment of cleistogamy.