It is nearly hard to discern whether a marijuana seed is female or male based on appearance. To test for the Y chromosome, you can use a lab test or a plant sex kit to determine the sex of a seed.  However, as the seeds begin to pre-flower, observable variations emerge. And here are two tips for identifying cannabis seeds: When male seeds are pre-flowering, they develop a pollen bag at the branch junctions. Male marijuana seeds develop far quicker than female marijuana seeds. Female plants produce a pale white pistillate. Female seeds, on average, take longer to grow.