Near sunset we may fancy them in silent meditation as if determining some mooted question of time or weather. For in case of long continued drought the reservoir systems of these great trees store up enough moisture to last them for three years, and they will blossom and fruit just the same without fail and on time! Over the entire length of these giants, run long ridges or flutings, which serve the plants as miraculous reservoirs for water: as the ridges expand, the plant becomes water-filled; and as the great tree uses up its moisture, these flutings contract into proper position, thereby exhibiting but one of the many marvels in engineering consummated by Nature, the Great Engineer. Along his twenty or twenty-five flutings she has given Sahuaro a formidable array of long sharp spikes which defy the approach of man and beast alike: grayish black spines, clustering on the lower ridges of the plant and never bearing flowers, and clusters of yellowish thorns, on the upper part of stem and branches, that bear the blossoms and fruit. Thirty to fifty feet tall, these sentinels of the desert tower above the baby Pincushion, the Cholla, the Creosote and Desert Sagebrush, and the other Cerei, which seem but tiny dwarfs in comparison. Columns of their massive trunks grow singly for a distance of ten to fifteen feet, then curve abruptly erect in candelabralike branches, terminating in masses of waxy white blossoms, the whole giving strongly the effect of a lighted candelabra in the dazzling sunlight. Full-grown Sahuaro weigh six tons or more; they are very sturdily constructed, vigorous and hardy, caring not for wind or weather or time. Woodpeckers make their homes in the waxy green trunks of old Sahuaro, and the injuries made by birds are sealed over by a coating of tissue from the plant itself. These coverings often take form of water containers and are so used by the Indians. The spiked armor causes Sahuaro to be feared by man and bird and beast, and the bold woodpecker and the hawk are almost alone in venturing to nest in their trunks.