The regularization parameters of xgboost

#1

I’m so confused that I did not find anything about this parameter(γT) in image
in https://xgboost.readthedocs.io/en/latest/python/python_api.html#module-xgboost.plotting ?

Could anyone please help me?

#2

Importance concerns the features alone. The regularization parameter is set during the training for the algorithm, it’s not involved in the feature importance if I’m not mistaken.