Known from only one extant native occurrence at the Presidio in San Francisco; plants there belong to a single clone. Five of six historical occurrences extirpated by urbanization; currently threatened by non-native plants, encroachment of native shrubs, and branch dieback due to fungal pathogen. USFWS uses the name A. pungens var. ravenii. See Madroño 19(6):200 (1968) for original description.