to asparagus. As these are more present in young asparagus, this accords with the observation that the smell is more pronounced after eating young asparagus. The biological mechanism for the production of these compounds is less clear. The onset of the asparagus urine smell is remarkably rapid while the decline is slower. The smell has been reported to be detectable 15 to 30 minutes after ingestion and subsides with a half-life of approximately four hours. Nomenclature A. officinalis is widely known simply as "asparagus", and may be confused with unrelated plant species also known as "asparagus", such as Ornithogalum pyrenaicum known as "Prussian asparagus" for its edible shoots. The English word asparagus derives from classical Latin but the plant was once known in English as sperage, from the Medieval Latin sparagus. This term itself derives from the Greek aspharagos or asparagos, but the Greek terms are of uncertain provenance: the latter form admits the possibility of a Proto-Indo-European root meaning "to jerk, scatter," directly or via a Persian descendant meaning "twig, branch"; but the Ancient Greek word itself, meaning "gully, chasm," seems to be of Pre-Greek origin instead. Asparagus was corrupted in some places to "sparrow grass"; indeed, John Walker wrote in 1791 that "Sparrowgrass is so general that asparagus has an air of stiffness and pedantry". The name 'sparrow grass' was still in common use in rural East Anglia, England well into the twentieth century. In Turkish, asparagus is known as kuşkonmaz, literally "[a] bird won't land [on it]", in reference to the shape of the plant. Cultivation Since asparagus often originates in maritime habitats, it thrives in soils that are too saline for normal weeds to grow. Thus, a little salt was traditionally used to suppress weeds in beds intended for asparagus; this has the disadvantage that the soil cannot be used for anything else. Some places are better for growing asparagus than others. The fertility of the soil is a large factor. "Crowns" are planted in winter, and the first shoots appear in spring; the first pickings or "thinnings" are known as sprue asparagus. Sprue has thin stems. A breed of "early-season asparagus" that can be harvested two months earlier than usual was announced by a UK grower in early 2011. This variety does not need to lie dormant and blooms at , rather than the usual . Purple asparagus differs from its green and white counterparts