Finding the right Species
You should be able to key through the first two steps of this key, then it gets more difficult. Try it and check your first two steps.
Your third step is choosing between 4 and 4'. There is a bit of conflicting information at this point that makes the choice difficult.
There are several characteristics to compare:
1) Whether the inflorescence is open or dense is a bit difficult to tell without being able to compare an open and a dense inflorescence.
2) There are more than 10 flowers [in an inflorescence] in those inflorescences that were photographed. That favors choice 4'.
3) The petiole is fairly close to 2 cm long (see petiole photo). Choosing between petioles > 2 cm and petioles < 2 cm, is not useful. (Additionally, the words "generally < 2 cm" for choice 4, and "petiole generally > 2 cm (0-3 cm in Berberis pinnata)" for choice 4', mean there are exceptions.)
4) Is the shape of the terminal leaflets "lanceolate, oblong, or narrowly elliptic" (choice 4), or "ovate to wide-elliptic" (choice 4')? The one in the "leaf" photo looks oblong to me, but another ("leaf2") looks slightly ovate. ...difficult to tell.
This is a case in which I would key both ways, then compare the descriptions of the candidate species.
Assignment:
There are 11 taxa (species, subspecies, and varieties) past this point in the key. This part of the assignment is more easily assessed (by me) in a quiz format. Therefore, the quiz that follows this lesson will ask you about each of these 11 taxa. For each, you will be asked why you eliminated them or why you chose the. You should use information from the key and/or from the description, and/or from other sources (e.g., CalPhotos or Calflora.
Reminder: If you did not initially enter the correct answers on the fourth page of this lesson ("Start keying"), go back and correct your answers before submitting.