Thursday, May 28, 2009

Late May 2009

"Attention everyone. It's May and the spring wildflower season is over. Everyone please return to your air conditioned houses. There is nothing to see here."

I have heard variations of this seasonal death sentence countless times over the years, and my reaction to it is still the same as it has always been: it ain't over yet.

In the minds of many, the Sonoran desert spring is the season of goldpoppies, lupines, and owl's clover with warming days, cool nights, and the supressed memories of rock salt and studded snow tires. It's that short window of time when the desert wakes up and explodes in color, splattering itself onto Arizona Highways magazine covers and making the now lush, drive-by scenery through "the desert" look as disarmingly safe and enticing as a mountain meadow, as if Julie Andrews could appear at any moment. It's the season to take the kids for a hike with a reasonable chance of survival wearing only baseball caps and a few pints of water tucked into a fanny pack. This is what I call "Part One" of spring and it usually lasts from mid-February to mid-April. It's the first part of the Sonoran desert spring that is generally inviting and accessible, yet notoriously fickle with its flower show and highly dependent on well-timed fall and early winter rains.

Part 2 of the Sonoran Desert spring is far more dependable but it's not for the faint of heart, which is why so many people roll up their awnings and point their motorhomes towards Wisconsin and Michigan in April. The homing instinct to arrive in Grand Rapids in time to watch the snow melt has cheated many poor souls from ever experiencing the spectacular, albeit hotter half of our spring. While the first half is dominated by ephemerals and relatively small perennial plants, the second half is dominated by the flowering of the deserts larger elements, like yuccas, agaves, cacti, mesquites, both of our native species of palo verdes, and ironwoods. In other words, just about everything that didn't bloom in February, March, and mid April is now hard at it in late April and May, including saguaros.

Here is a short list, in ascending chronological order, of what common native plants to expect to flower exclusively (or nearly so) during Part Deux of spring in the environs of Boyce Thompson Arboretum.

April

  • Boyce Thompson hedgehog- Echinocereus boyce-thompsonii
  • Pincushion Mammillaria- Mammillaria grahamii
  • Buckhorn cholla- Cylindropuntia acanthocarpa
  • Engelmann prickly pear- Opuntia engelmannii
  • Blue palo verde- Parkinsonia florida
  • Soap tree yucca- Yucca elata
  • Banana yucca- Yucca baccata
  • Jojoba- Simmondsia chinensis

May

  • Native mesquite- Prosopis velutina
  • Catclaw- Acacia greggii
  • Foothill palo verde- Parkinsonia microphlla
  • Ironwood- Olneya tesota
  • Saguaro- Carnegiea gigantea
  • Chain fruit cholla- Cylindropuntia fulgida

In addition to these are several carryovers from the first half, including:

  • Fairy duster- Calliandra eriophylla
  • Flat top buckwheat- Eriogonum fasciculatum
  • Creosote- Larrea tridentata
  • Ocotillo- Fouquieria splendens

This was the best year for foothill palo verdes that I've seen since 2005; every hillside was covered in an unbroken sea of yellow in all directions, like being emersed in a low hanging sulfer fog. Foothill palo verdes have a light, chiffon-like yellow compared to the more saturated yellow of the earlier flowering blue palo verdes and they are the dominant tree on the hillsides surrounding the Arboretum. 2005 was also a great year for the prolific brittlebush which grows amongst the foothill palo verdes but flowers a month ealier, making that year even more spectacular than this year with an unbroken yellow colorfest for two solid months from April through May. Still, 2009 has been no slouch with ironwoods flowering as densely as I have ever seen them.



In the end, all superlatives used in the descriptions of wildflower displays are inherently subjective. What might be "mind-boggling" to me could be merely "spine-tingling" to someone else. The important thing is not to give up too early. Though summer is definitely knocking at our door, the desert still has a lot to give to those of us that are willing to put on a wide brim hat, carry quarts of water rather than pints, and, at the very least, give the desert a second chance.

Kim Stone
Horticulturist