Mountain wildflowers are usually associated with the days of summer high in the Catalina Mountains, but some are bursting into bloom now at  8,000 feet in the range north of Tucson.

Plant experts say it appears to be another result of Southern Arizona’s uncommonly warm, dry winter.

“From my own experience in the Catalinas, this spring appears to be a pretty early one. This is probably because of two things: It has been a very warm and dry winter, and the autumn precipitation we received this year came relatively early,” said Paul CaraDonna, a doctoral student in the University of Arizona’s department of ecology and evolutionary biology. He is co-author of a study on changes in the timing of wildflower blooms, published this year in  Proceedings of the National Academy of Sciences.

“Both precipitation and temperature play very important roles in signaling to plants when it is a good time to grow and flower,” CaraDonna said. “The overwhelming trend across the globe, in all sorts of different ecosystems, is that as the climate warms, biological events are occurring earlier. Early flowering times and early springs associated with warming temperatures are most pronounced at higher latitudes and higher elevations.”


Frank Rose, author of “Mountain Wildflowers of Southern Arizona: A Field Guide to the Santa Catalina Mountains and Other Nearby Ranges,” said early blooming appears to be partly an effect of drought.

“In general I think it is true to say that there is a trend toward earlier blooming times for most of the flowers,” Rose said. “The dryness affects this. Some plants rush to flower in very dry weather, and have flowers lower to the ground than they normally are.”

He adds  whimsically: “I imagine the plants thinking, ‘It is very dry — not much rain in the forecast. Let’s get on with the blooming right away and not waste a lot of energy building long stalks and leaves.’ It is also possible that plants don’t think like that.”


Most trails above 7,500 feet in the Catalinas and other ranges near Tucson will have some blooms now and more in the coming weeks.

The Box Camp Trail, which begins at an elevation of about 8,000 feet between mile markers 21 and 22 on the Catalina Highway, is graced with lots of yellow groundsel flowers and some purple-blue lupines.

Contact reporter Doug Kreutz at or at 573-4192. On Twitter: @DouglasKreutz