Watching the Saguaro Bloom

The flower of the giant cactus, or saguaro, is Arizona's State Flower. That this should be so is very appropriate, for no other plant means "Arizona" to so many people. The saguaros are the great drawing card of our arboreal desert and rank along with the Grand Canyon and Painted Desert in appeal to visitors in the Land of Sunshine. Arizona shares its giants with Sonora, but with no state in the Union except for a few strays growing on the California side of the Colorado River.

The great giants stand out on the desert landscape like huge exclamation points, mutely proclaiming to all the world that this is Arizona. Along the busy highways some of them have been "snapped" so often they almost seem to draw themselves up and pose whenever a car pulls off to the side of the road. Saguaros never grow tiresome, each one being a distinct individual, and their variation in form is infinite. The massive plant is the largest succulent in the United States and one of the largest in the world. The National Park Service has set aside a giant cactus "forest" near Tucson, as a national monument. Another tract, between Ajo and the Mexican border, is similarly protected for the benefit of the public. In the latter monument two interesting related species, the organ pipe cactus and the sinita, grow along with the saguaro. In late Máy and June the three species bloom simultaneously.

The early Spaniards found the saguaro of great economic importance to the natives. Their accounts contained many references to the pitahaya and to other cacti that yield edible fruit, especially the pitahaya dulce or organ pipe cactus. It is curious, however, that the conquistadores and padres seemed to have had interest only in the utilitarian aspect of the vegetation. Not until the Americans came into our region, three centuries after Coronado's famous exploration, did accounts of scientific value become available.

The first technical description of the saguaro was written in 1848 by George Engleman, famous botanist and physician of St. Louis, Missouri, from notes and sketches furnished by Lieutenant William H. Emory. Emory was a topographical engineer who accompanied Colonel Kearny in 1846 on a forced march through Arizona, then Mexican territory. Kearny's detachment, part of the "Army of the West," was traveling in a great hurry to reinforce the American soldiery in California which was in precarious combat with the Spanish Californians. Emory was a remarkable observer and never missed an opportunity to take astronomical observations on latitude and longitude, note details concerning the natives, or observe the topography along the route of march. He also collected plant specimens. The cacti did not submit any better then than they do now to being converted into dried botanical specimens, so the party's draughtsman, J. M. Stanley, sketched some of the plants. Consequently, Engleman was enabled to describe several new cacti including the saguaro, which he called Cereus giganteus.

WATCHING the ... a blossom

It seems unbelievable that any question should remain unanswered concerning the blooming of the State Flower. The sight is commonplace to Arizonans and nearly every one has seen the branches profusely crowned with the beautiful virgin-white flowers. But the fact is they are so inaccessible way up at the tips of the towering branches that few persons have gone to the trouble to become well acquainted with them, and even eminent cactus authorities have been a little confused as to whether the flowers are nocturnal or diurnal. However, with few exceptions (notably Palmer Stockwell in his bulletin on Arizona Cacti) authorities have agreed that the saguaro is day-blooming, or playing safe have been noncommittal on the subject.

Saguaro BLOOM

In the past flowering season we took the trouble, and a very pleasant "trouble" it turned out to be, to sit up with the giants for a few nights. Several evenings of quiet observation in the starlit hills alone with the giants put an end to our doubts. We found the saguaro to be night-blooming, in fact a "night-blooming cereus." The flowers, although truly nocturnal, do not wither until late the following afternoon, but to our knowledge they never last longer than twenty-one hours. Our photographs show how and when the flowers open.

Unlike some of the other night-blooming cacti, the saguaro buds seem to be in no hurry to open. They wait until quite a while after the sun has set, seemingly until they can be certain that night actually has come to stay. Then they begin to open in a slow, measured manner befitting the dignity of the great giant of the desert. The pictures were taken at hourly intervals from 8 to 12 o'clock at night, on May 23, last year and at 10 oclock the following morning. About 15 minutes before the first picture was taken the bud showed, by a loosening of the outermost petals near the top, that it was ready to open that night.

Although the pictures were taken primarily to show the opening of the flowers, other details are of some interest. At the right can be seen a wilted flower that had opened the preceding night. Note that it had shriveled further and that its petals were much more incurved the next morning. The view includes several large buds that were approaching the flowering stage and, near the bottom, two old brown withered flowers. In the rear can be seen a side view of another flower that was opening the same night.

We kept saguaro flowers at hand during the flowering season, for observation, and asked nearly every one who happened by to smell. To some the flowers smelled like cantaloupe, but to most persons the odor resembled that of ripe watermelons. While the flowers are opening at night the petals are pure white and somewhat translucent, but by morning they change to creamy-white and appear rather opaque.

The giant cactus is no exception to the general rule followed by the pessimistic cactus clan in producing a large quantity of pollen and a great number of seeds. Pollination is effected mainly by insects, but the insects have their own affairs to attend to and no doubt much of the pollen never reaches its mark. The necessity for developing many seeds is also obvious. Great quantities are eaten by birds, and of the remainder but few fall in situations favorable to growth of seedlings. The seedling saguaros, though abundant, are very juicy and tender at first, and not many survive long without the protection of shrubbery or brush and a reasonable amount of plain good luck.

We moderns have drifted away from nature as a provider and concern ourselves with it largely for pleasure. This is not true of the aboriginal inhabitants who preceded us on the desert nor their descendants. They studied nature from necessity and learned to make some use of nearly every plant. Their acquaintance with the giant cactus was intimate and profitable. The stems came in handy for constructing shelters and the plant supplied other needs, but it was the abundant crop of juicy palatable fruit that meant the most to the natives. Possibly the aborigines could not have survived permanently in the inhospitable desert without the saguaro. The crop is unfailing, for the plants have enormous capacity for water storage and produce a