A wild lilac bush in the Santa Rita Experimental Range.


Plant observer Patricia A. Pearson was so impressed by the life of a wild lilac bush growing in the Santa Rita Mountains that she bought one for her Sahuarita yard.

Edy Alderson, who grew up on a Midwest family farm, quickly learned how to grow desert plants by watching them in nature.

Their experiences show the personal benefits of practicing phenology.

Phenologists study seasonal changes that plants and animals go through over several years in their environments.

They observe such plant changes as when buds form, branches leaf out, flowers bloom, fruit ripen and leaves fall. They note what animals use them for food, nesting or other reasons.

By coupling that information with climate data, scientists can understand how life responds to climate change.

For instance, Alderson explains, cold weather that hits an area later than usual causes some flowering plants to bloom later. Migrating birds that feed on or pollinate those plants may arrive to the area with no food source available.

This scientific field and how it can help even gardeners tending their own yards will be demonstrated at Saturday's Phenology Day. The new event includes walks along some of the 75 miles of phenology trail segments in Tucson. Folks can attend some or all of the activities.

The trails allow people to observe plants and animals, and log data for scientists or for themselves.

Pearson and Alderson, both master gardeners, say their observations make them better gardeners.

They have spent a year following mesquites, ocotillos and that wild lilac bush in the Santa Rita Experimental Range next to the Santa Rita Mountains.

Pearson was inspired after watching the non-native lilac bush thrive in the desert.

"I was so excited about that one that I went … and bought one," she says. "This has been encouraging me to try different things."

Alderson says she's always been aware of the cycle of crop and landscape plants that grew easily in her native Illinois. Phenology taught her how things grow in the Sonoran Desert.

"It's a whole new set of things in the desert," she says. "I'm a better observer of what's going on in my garden. I didn't have to pay as much attention in Illinois."

If you go

Phenology Day

• What: Free activities that demonstrate the scientific study of phenology.

• When: 9 a.m.-3 p.m. Saturday.


9 a.m.: Introduction to phenology and phenology trail walk, Pima Cooperative Extension or Santa Rita Experimental Range Florida Station in Green Valley.

10:30 a.m.: Visits to phenology trail segments at Biosphere 2, Audubon Mason Center or University of Arizona campus arboretum.

12:30 p.m.: Phenology research talk at USA National Phenology Network (USA-NPN) office, 1955 E. Sixth St.

1 p.m.: Trail segment tours in Sam Hughes and Rincon Heights neighborhoods.

2:30 p.m. Ice cream social, USA-NPN office.

• Information: 622-0363, www.usanpn.org

Contact Tucson freelance writer Elena Acoba at acoba@dakotacom.net.