Where is sklearn finding feature_names in the iris dataset?

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Apologies for the noobish question.

I'm playing around with the iris dataset that comes with sklearn. When I enter:

iris.feature_names

It outputs:

['sepal length (cm)',
 'sepal width (cm)',
 'petal length (cm)',
 'petal width (cm)']

What I don't understand is where it's getting those names. I opened the iris CSV in Excel and I cannot find any reference to any of those words.

What am I missing?