Tuesday, July 12, 2011

The Arizona Queen of the Night, Peniocereus greggii

Two of my watercolors of the Night-blooming Cereus
Last night the Arizona Queen of the Night (Peniocereus greggii) bloomed in our part of the desert. Buds on all plants in our area simultaneously opened at sunset, the petals still growing and stretching outward for hours, until finally the dense anthers and star-fish-shaped stigma were presented above a skirt of slightly drooping petals.

I don't know what signal synchronizes this magical event. It's not day length, because it can occur any time between mid June and the beginning of August, and Tohono Chul Park 30 miles to the east celebrated the bloom about a week ago. The blooming is also rather independent of the onset of the rainy season, probably because the plants are drawing on the resources of a large underground bulb, although the hydration state of a plant seems to decide whether it's going to bloom in any given year at all. Sometimes, often following a very rich flowering, all the visible parts of a plant just dry off and crumble, and it takes years until the next flowers appear.

 The vegetative parts of this cactus are so thin and unassuming that 
they blend in completely with the branches of the Creosote bush. Our friends Frank and Lynn bought the land next to us years ago and were very much looking forward to the flowers of one Queen that we had planted, but we were all surprised by several other large plants that suddenly opened their flowers last night. 

The cactus flowers stay open into the early morning hours, so a couple of hours before sunrise Cody and I went out into the desert to find some more blooming Arizona Queens. At night usually a cloud of sweet fragrance is the first sign that leads pollinators and photographers to the plants. But at dawn, the pale flowers stand out like beacons. 

The flowers are about the size of a baseball. Many plants are not more than knee-high, but today I found several that were taller than I. This is impressive considering that a heard of cattle had a devastating 4 year run in this 400 acre parcel of state trust land. Wile the bovines destroyed Paloverdes, Prickly Pears and Ironwood trees,  they left the fragile stems of E. gregii untouched in their cover of Creosote branches.

This ten-flower cactus was the prize of the morning. I wished you could smell the cloud of sweet fragrance that surrounded it. This smell attracts the nocturnal sphingid moths that are the main pollinators of P. greggii. Big Manducas and the White-lined sphinx Hyles lineata are usually very common, but this year I have only seen a few at my black lights. 

When the moths are scarce unpollinated flowers probably stay fresh longer and their the beacon-like appearance at day break may insure visits by bees, although those promiscuous pollen gatherers are probably not the most reliable pollinators.


  1. They are beautiful flowers. How pure and white they look.

  2. What an exquisite flower! I had a cereus once, and the bud-to-blossom process was so wonderful to watch. Thank you for posting these photos!

  3. From Barbara Robeson via flickr:
    Margarethe, I just read this blog entry and this is the most beautiful thing I have ever seen. I had not heard of this flower and its magnificent orchestrated performance - how wonderful. I must see this.
    Your paintings are quite wonderful and I think you capture the amazing luminosity.

  4. These are truly amazing...the flowers ,the photos and the paintings . The eye of the artist always sees beyond a camera lens . You truly have a talent which you very generously share . Thank you.

  5. How interesting that your 'population' of P. greggii bloomed a week later than ours. How fun to find more plants by finding the blooms. We found a second specimen on our property that way too. Wonderful post, photos and painting!

  6. Wonderful and very interesting post as always! :) Your watercolors are absolutely beautiful!!

  7. Looks beautiful if no bees in the flower. The post was good. Keep it up.. Ocean Audit