Causes of ALS. ALS is a somewhat diverse and decidedly mystifying disease. In more than nine out of every 10 cases diagnosed, no clear identifying cause of the disease is apparent, that is, patients lack an obvious genetic history, complete with affected family members.
1 Aristocrat - this variety features a waxy skin and is medium green in color. 2  Black Zucchini - very dark green skin and almost white flesh, very common variety of zucchini.  Zucchini Gadzukes - dark green with distinctive light green ridges, resembles a star when sliced crosswise, compact plant.
Look for a uniform green color encompassing the entire zucchini. Look for zucchini that are 6 to 8 inches in length. Select zucchini that is fairly firm and not too soft. It should feel slightly more flexible than a cucumber, but not by much. Avoid soft zucchinis because the softness is a sign they will be inedible very soon.