Native to south - central Mexico, Stenocereus pruinosus is columnar with stems that branch at the base and reach 20 feet in height in the wild. S. pruinosus usually have only 5 to 7 ribs and the new growth produces a grey powdery bloom and attractive patterns on the stems, hence the name "Grey Ghost". It produces nocturnal white flowers with a pinkish tinge and like the other Stenos the fruit is spiny till ripe, and edible.
     I have one of these in my garden and another potted. I'm thinking of planting them both elsewhere in the garden where they'll have room to grow. My first location may not be a good choice given the size they can reach. Xenomorf, a fellow member of the Davesgarden.com gardening forums, allows me to use his pictures on the site. Thanks Xeno :-) Also check out a gallery of some of his other pictures in the Photo Galleries/Friends section. Below is a picture of the flower.