consider the definitive "pear flavour". Colours of the pear vary from green (when unripe), to yellow (ripe) and red. Red Bartletts or Williams are very similar to the traditional Williams, aside from ripening to a reddish colour rather than a yellow colour. Red-skinned mutant clones (i.e. "sports") of the Williams are increasing in popularity, including three major varieties in the US: the Max Red Bartlett, the Sensation Red Bartlett, and the Rosired Bartlett. One study of several macrosatellite loci in 63 European Pear (Pyrus communis L.) cultivars did not distinguish Max Red Bartlett and Sensation Red Bartlett from the standard Williams, which was expected since the red mutants were derived from the Williams by mutation. Dozens of other cultivars and hybrids have been created from Williams, created for properties like cold resistance, ripening time, skin colouration, and grafting compatibility. Best when picked with the internal pressure of the pear is between , the pear should still be green and relatively hard when picked. Optimum conditions for ripening are in dry shady areas, and ripening usually takes 7 to 10 days from when the pear was picked. As the pear ripens the color will slowly change to a soft yellow and the pear will soften. Commercially produced pears are normally picked and shipped to the stores while green. Tree Pear trees are usually productive for 50 to 75 years though some still produce fruit after 100 years. Height: with slightly less spread Flowers: White flowers grouped in a corymb Blooming time: April–May (in the Northern Hemisphere) Fruit and seeds: Large, golden yellow skin, brownish red blush, classic shape with smooth, white flesh. Harvest from mid-August to mid-September (Northern Hemisphere). Leaves: The leaves are simple, glossy green leaves that alternate on the twig. They grow up to long, are thick with slight midrib curves folding the edges inwards. They have fine teeth on the margin. Elevation: Habitat: Orchards and landscaping Production and uses US pear production In 1985, this variety represented 80% of US pear production while in 2004 it represented 50% of reported pear production, displaced primarily by the continuing growth of d'Anjou and Bosc pears, both winter pears more tolerant of cold than the Bartlett. While more pears are sold fresh in the US than processed, Bartlett pears are the primary choice for canned halves, puree, and most pear juice and nectar in the US, comprising about two-thirds of Bartlett