Sunday, July 18, 2010

Bloom Night

Tohono Chul Park in northwest Tucson held its nineteenth (19th!) annual “Bloom Night” this past Friday, July 16, 2010. The event is done on short notice as park personnel evaluate the potential for Night-blooming Cereus flowers to be at their peak. I subscribed to the park’s Facebook status, so was alerted on Friday that the stage was set for that night.

Night-blooming Cereus, also known as “Queen-of-the-Night,” “reina-de-la-noche,” and “deer-horn cactus is known scientifically as Peniocereus greggii (formerly Cereus greggii). The plant is easily overlooked entirely in the daytime, as the slender stems, with four or five ribs, appear to be lifeless, propped against a tree or shrub under which the cactus grew. The Night-blooming Cereus can reach to eight feet in height, with the help of its “nurse” tree, but is usually substantially shorter. The majority of those I saw Friday night were roughly two to three feet tall.

Once each year in June or July the plant puts forth shockingly beautiful blooms under the cover of darkness. Each flower is a “one night only” affair, hoping that a sphinx moth will find it and pollinate it. The flower enhances its chances of this by emitting a fragrance that carries for up to one hundred feet. Moth olfactory senses must be vastly more acute than our human noses. Unless I literally stick my schnoz into the flower I get nothing.

Tohono Chul is a private park, so while they do stay open late (6:30 PM – midnight) for this one night, they also charge you for your visit. At only five dollars it is a bargain in many ways (for one thing, the usual daytime admission is $7). The park is a combination of natural desert and planted examples of plants from Arizona, Mexico, and elsewhere. There is a “tea house,” gift shop, and more on its 49 acres.

It is a pity that there are not more after dark programs here and at other parks around the Tucson area. It is at night that one encounters many of the more interesting flora and fauna. Ironically, I found Tohono Chul’s example of Giant Sprawling Morning Glory, Ipomoea longifolia, to be even more spectacular than the star of the show. Judge for yourself (below).

The park obviously waters their plants considerably more than occurs naturally, as you won’t see an enormous Sacred Datura (Western Jimsonweed), Datura wrightii, like this anywhere in the desert, at least in my experience.

The animals in the desert night can be equally spectacular. Field crickets (genus Gryllus) add an auditory accompaniment to any evening stroll.

They have to be careful they don’t blunder anywhere near a tarantula burrow, though, or get run down by one of the agile wolf spiders (family Lycosidae) that are on the prowl.

Most of the trails in the park are marked on Bloom Night with luminaries (candles inside paper bags), but since I had both a headlamp and a flashlight, I took the liberty of exploring some of the paths that remained in the dark. I was rewarded with arguably my most exciting find of the night: a small Western Diamondback Rattlesnake, Crotalus atrox, coiled along the edge of the path. It remained perfectly still the entire time I snapped images and introduced it to other curious visitors.

That is perhaps what I enjoy most about events like this: the opportunity to share my own discoveries with others, and give them a little knowledge, too, providing I know something about the animal or plant at hand. I must have spent fifteen minutes showing a steady parade of other visitors this female funnel-web weaving wolf spider (Sosippus californicus) toting her egg case across her silken sheet. Some folks were disappointed that it was not a Night-blooming Cereus flower I was taking pictures of, but most were quite curious and took their own images with phones or point-and-shoots. I love that.

One final note, you never know who you are going to meet at these shindigs. I saw Karen Wright for the first time in years. She’s the wonderful photographer who took the portraits of me that adorn my blogs and the back of the Kaufman Field Guide to Insects of North America. I also met a wonderful young couple who graciously offered me a ride home after the show. Thank you, Kerrah and Tim, for your company and generosity.


  1. My friend George had these blooming in her yard just last night. Check out her post at

  2. Hi! I think you may have solved a question for me. We have observed a greyish brown spider with striped legs that carries its egg sac that lives by a local creek (Orange County, CA), that skims over water, that hops. I thought it looked like a grass spider, but we saw it carry its egg sac (my 4yo originally noticed it and told me to come see a spider wearing a diaper, lol!) I'll have to check around next time to see if there are funnel webs around. Thank you so much for posting your observations, here also:
    I haven't been able to find much else about it anywhere.