Yes. Zucchini, crooknecks and patty pans (scallops) are all the same species. They cross pollinate readily, but it does not affect the fruit only the next generation.

Thank you! Is it the same with pumpkin?

Yes. does not affect first generation fruit. Many halloween type pumpkins are C. pepo and cross with crooknecks, straight necks, scallops and zucchini. Some of the larger orange ones are c. maxima. there are also C. moschata and C. mixta varieties. They don't naturally cross with different species.

very interesting, i am growing some Rouge Vif d'tampes, they do get a bit on the red hue, i would like to save some seed,do you think they will only pollinate with themselves?

Rouge Vif d'tampes is a C. maxima. It will cross with other C. maxima. That group includes the pumpkins like Big Max, Atlantic Giant, Jarrahdale, Hubbards, Buttercup types,Kabocha. It won't cross with summer squash or Halloween type pumpkins.

hey thanks, i have most of those growing except the atlantic giant and jarrahdale,, i will take precautions with a few of the rouge Vif d'tampes to avoid unwanted crosses. and maybe a few of the others time permitting.thanks again