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There are many books that will guide you, and also many online sites. If it is a native wildflower, most regions have online lists to help. For garden plants, see the Web Links to the left. The one...
if the colors are very bright and BEAUTIFUL then it is a male and if the colors are dull and boring then it is a female
Female what? Female goats with horns are common, Female sheep with horns, not so much, but some breeds do.
Well male flowers have different flower parts than females. Did you know?: Female flowers actually have ovaries in a flower kind of way