Pineapples

The pineapple (Ananas comosus) is a tropical plant and fruit (multiple), probably native to Uruguay, Brazil or Paraguay. It is a tall (1–1.5 m) herbaceous perennial plant with 30 or more trough-shaped and pointed leaves 30–100 cm long, surrounding a thick stem. The pineapple is an example of a multiple fruit: multiple, spirally-arranged flowers along the axis each produce a fleshy fruit that becomes pressed against the fruits of adjacent flowers, forming what appears to be a single fleshy fruit. The leaves of the Smooth Cayenne cultivar mostly lack spines except at the leaf tip, but the Spanish and Queen cultivars have large spines along the leaf margins. Pineapples are the only bromeliad fruit in widespread cultivation. It is one of the most commercially important plants which carry out Crassulacean acid metabolism, or CAM photosynthesis.
The fruitlets of a pineapple are arranged in two interlocking spirals, eight spirals in one direction, thirteen in the other; each being a Fibonacci number. This is one of many examples of Fibonacci numbers appearing in nature.
The natural (or most common) pollinator of the pineapple is the hummingbird. Pollination is required for seed formation; the presence of seeds negatively affects the quality of the fruit. In Hawaii, where pineapple is cultivated on an agricultural scale, importation of hummingbirds is prohibited for this reason.
At one time, most canned and fresh pineapples came from the cultivar "Smooth Cayenne". Since about 2000, the most common fresh pineapple fruit found in U.S. and European supermarkets is a low-acid hybrid that was developed in Hawaii in the early 1970s. Pineapple is commonly used in desserts and other types of fruit dishes, or served on its own. Fresh pineapple is often somewhat expensive as the tropical fruit is delicate and difficult to ship. Pineapples can ripen after harvest, but require certain temperatures for this process to occur. The ripening of pineapples can be rather difficult as they will not ripen for some time and in a day or two become over-ripe, therefore, pineapples are most widely available canned.