When these
flower, they have a tube behind them that looks almost like a mini cucumber if i let it grow big enuff.
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OK, shows what i know dunnit.
They're female if they have an embryo fruit behind the
flower. They require pollination by a male
flower in order to set the fruit. Bees will normally do this for you. The males are similar but they don't have the little fruit and with most cucurbitae are on a longer stalk. You can take off a male
flower, remove the petals and pollinate the female by hand. Do so in the mornings, (just because), and get the
flowers when they are fresh looking.
This is the case for all the vegies you mentioned.
I'm not a big fan of removing the
flowers off anything in the vegie patch, so i'd leave them on there. I always figure if they're ready to produce then i'll let them. (However, with citrus, for example, i'm all for removing the fruit for the first few years but they aint annuals.)