Bloom Watch #7

Another rogue player …

“It looks like we have another rogue cactus on our hands!” said Chris on Monday morning. 

Queen of the Night #379 is at the head of the pack with two buds measuring 110mm and on track to bloom this week. The rest of the regal monarchs are still between 40mm-60mm. 

“With the increase in humidity this week, (40% this morning!) they may pick up the pace. I’ll definitely keep you all posted.” he says. 

“The Queen’s Court at the Overlook has several cacti ready to bloom. One was blooming Friday night! Check them out if you’re brave enough to go outside!” 

Gardens Manager, Chris Kibler, shows where one of the lighting units is installed above a bloom location in eager anticipation of Bloom Night.

A Botany Lesson

Speaking of the Queen’s Court (the row of potted cacti positioned at The Overlook here at Tohono Chul), one of the courtiers, Peniocereus striatus, illustrates a fascinating example of convergent evolution in the plant kingdom. Convergent evolution is the process of distantly related organisms evolving similar traits in order to adapt to similar situations. Introducing, Euphorbia cryptospinosa, native to the landscapes of Ethiopia, Somalia, and Kenya.

Euphorbia cryptospinosa close-up of stems. (Photo courtesy of Dave’s Garden davesgarden.com)
Euphorbia cryptospinosa: Flowering plant in cultivation. (Derivative of a photo by Frank Vincentz, contributor to the collection of photos courtesy WorldofSucculents.com)

This completely unrelated plant from the opposite side of the planet has been shaped by it’s own climate to look much like our Peniocereus striatus. Both have tuberous roots, with slender cylindrical stems that are camoflagued amongst the shrubs where they both grow in sandy, gravely soil. In addition to being succulent, both have developed an ingenious way of preventing extra water loss during drought.

Stomata are unique to plants and are the specialized groups of cells that open and close to allow for gas exchange of CO2, oxygen, and water vapor, through the epidermis of a plant. In our courtier and our friend the Euphorbia cryptospinosa, the stomata are restricted to narrow furrows that run vertically along the stems. When they have acquired sufficient moisture, these stems are plump and the stomata are more exposed to the air to enable gas exchange, but still shielded from the wind.

When the plant stems lose water, the furrows are sucked in from this water loss and they begin to close up like an accordion. By enclosing their stomata this way, they preserve their thin stems from shriveling up, even in very dry habitats. By studying comparative anatomy in this way, we can learn a lot about how plants work. Thanks to the University of Arizona Herbarium for providing this research for free so we can all level up our botany!

(Source: https://cals.arizona.edu/herbarium/sites/cals.arizona.edu.herbarium/files/old_site/assoc/people/rfelger/1997_felger_henrickson_convergent_evol.pdf )

By Tracey Till, Propagation Associate

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Bloom Watch #5

Cruel Summer

This is when we remember why it’s called the desert. The insects in the trees seem to imitate the sizzling Sonoran heat. Critters take refuge in the shade and their cool burrows. They drink from the fountains and hoses as we water the flowers. Days are long and the sunsets beautiful. Saguaro seeds disperse in the full bellies of birds. Prickly pear fruit turns color. 

Waiting for rain.

One of our dedicated gardeners, Shauna, performed her weekly duties of tending to the Queens by providing them with the necessary watering. Supplemental water ensures the vitality of these special plants during times of excessive heat and lack of rainfall.

“I’ve been watching, and the rain in the forecast keeps getting moved a day farther away,” she said. The buds we checked this week were between 40mm and 50mm.  

“No real change from last week.”  We are still approximately 1-2 weeks away from Bloom Night.

Cooking Up A Storm 

The University of Arizona’s CLIMAS has this to say about our monsoon season: 

“The monsoon is driven by the sun heating up the land and the Pacific Ocean at different rates, with land surfaces warming more quickly than the ocean. The warm land creates low-pressure zones as hot air rises… The moisture-laden monsoon air travels north to Arizona and New Mexico, encouraged by the pressure difference between the hot, parched southwestern air and the cooler Mexican air.” (source)

We might never know exactly why the Queen decides to bloom when she does, but from careful observations collected over the years in our little patch of desert, it seems to be closely linked with the occurrence of this pattern. 

Tohoho Chul’s water harvesting garden, Sin Agua, in 2022

It’s a busy time and a slow time here in the desert. A hurry up and wait. Where there is water, there is abundant growth. In our nurseries and in the garden we are all trying to keep up with the vigor of our plants as they soak up this solar energy. But by mid-afternoon, there is a quiet in the garden. The desert has some time to herself. 

Rebel Flower Update

If you’ve been keeping up with Bloom Watch, then you know that last week we had a rebel flower on our hands. One of the Peniocereus greggii buds decided to bloom ahead of schedule, catching our gardening staff by surprise.

As always, the unpredictable nature of these special plants is keeping us on our toes. But fear not, nature enthusiasts! The rest of the buds are on track and expected to grace us with their beauty in approximately 1-2 weeks.

Stay tuned for more updates as we inch near the arrival of the Queen (the rest of them, that is)!

By Tracey Till, Propagation Associate

Don’t miss the big night! Sign up for Bloom Watch emails here. 
Be sure you select “Bloom Watch” on the dropdown menu!