Yes. Female plants have XX as sex genes. Male plants have XY. When you cross two plants they pass on half of chromosomes. That half is 'in' a pollen grain and in a calyx, and isn't always the same half. When you take pollen from a female it doesn't matter which half she passes on, it's always an X, so crossing two females results in XX, which is a female. Lesbian plants can only create daughters. Tiresias Mist and Lesbian Dream are examples of CS products, another and better option is spraying STS instead of CS.