Hass is a cultivar of avocado, with dark-colored, bumpy skin. It is correctly pronounced /'hÃ¦s/, as in "hassle", not */'h??s/, like in the common misspelling "Haas". It is named for its originator, a mail carrier and amateur horticulturist Rudolph Hass. It is the most important avocado in the commercial market worldwide. In the United States, it accounts for more than 80% of the avocado crop, including 95% of the California crop, and it is also the most widely grown avocado in New Zealand. It produces a medium-sized fruit, weighing 200â€“300 g. The skin turns a dark, purplish-black when ripe, while the skin of "green" cultivars remains green. When ripe, it yields to gentle pressure; soft Hass avocados are generally considered over-ripe and possibly rancid.[citations needed] All Hass avocado trees are related to a single "mother tree" that according to Rudolph Hass's family was grown from seeds purchased from A. R. Rideout of Whittier, California, who was believed to be obtaining seeds from any available source, even garbage. (According to the California Avocado Commission, Hass bought a whole tree from Rideout, "an innovator and pioneer in avocados".) Rideout showed Hass, who had no horticultural training, how to care for the seedling and in 1926 Hass planted it at his 1.5â€“acre grove at 430 West Road, La Habra Heights, California. After attempts to graft productive branches from pre-existing Fuerte variety trees (then the predominant cultivar) onto the seedling failed, Hass was convinced to simply let it grow. Although the exact variety of the original seed is uncertain, there is evidence[weasel words] that a large number of Rideout's seeds were from the subspecies Persea americana guatemalensis. Hass patented the resulting tree in 1935 â€“ the first US patent on a tree, and made a contract with Whittier nurseryman Harold Brokaw to grow and distribute the trees produced by the seeds of the "mother tree"; Brokaw was to receive 75% of the proceeds. He specialized in the new variety, and he frequently sold out of the trees. The Hass variety produces fruit year-round, unlike the Fuerte, and has more and larger fruit, with a longer shelf life, and a richer flavor. Although Hass made a profit of less than US$5,000 from the patent (his newfangled patent was not well-respected by other growers, who used single Brokaw-provided trees to graft entire orchards), the US avocado industry today makes over $1 billion annually from the heavy-bearing, high quality fruit of Hass's cultivar, and it accounts for around 80%, worldwide, of all avocados grown today. The "mother tree" died at 76 years old and was cut down on September 11, 2002, after a decade-long battle against phytophthora ("root rot"); two plaques at a private residence at 426 West Road mark the spot where it grew. Each year, the City of La Habra Heights celebrates the internationally famous Hass at the Annual La Habra Heights Avocado Festival in mid-May. Founder Rudolph Hass died in Fallbrook, California (of a heart attack, at Fallbrook Hospital) in 1952, the same year his patent expired and not long after establishing a new 80-acre (320,000 m2) orchard. Hass avocado trees, like some other cultivars, have a tendency to bear well only in alternate years. After a season with a low yield, due to factors such as cold (which the avocado does not tolerate well), the trees tend to produce abundantly the next season. This heavy crop depletes stored carbohydrates, resulting in a reduced yield the following season, and thus the alternate bearing pattern becomes established.