Principal Taxa

• Taxonomists assign rank to taxa. The taxon Plantae (the plant kingdom) enjoys top rank. The lower taxa in descending order of rank are: divisions, classes, orders, families, genera, species, and subspecies. Each of these taxa is a subdivision of the taxon immediately above it. Intermediate classifications also exist between these main categories, such as, subclasses and subfamilies.
  
  

System of Linnaeus

• Carolus Linnaeus, an influential 18th century botanist, placed the apple in a class that he called Icosandria. He defined Icosandria as plants that have 20 or more stamens (male parts) attached to the calyx (the cup of leaflike sepals below the flower petals). He also placed apples in the order Pentagynia (which means five female parts) and in the family Pomaceae. (Pomum means fruit.) Finally, he assigned the name Pyrus malus to distinguish the apple from all other plants.
  
  

Taxonomy after Linnaeus

• Later taxonomists changed these names. August Eichler grouped the flowering plants with the conifers in the division Spermatophyta and placed the flowering plants in the class Angiospermae. Others grouped all vascular plants (ferns, conifers, and flowering plants, which have xylem, in which water flows, and phloem, for sap flow) into a single division called Tracheophyta. A currently popular system places flowering plants in a division called Magnoliophyta and a class called Magnoliopsida.
  
  

Rosaceae

• The apple tree belongs to the rose family Rosaceae.rose rose image by Freddy Smeets from Fotolia.com
  
  Recent systems of taxonomy place the apple tree in the order Rosales and the family Rosaceae, though the Linnaean name Pomaceae hasn't disappeared completelly. The apple tree has flowers similar to most members of Rosaceae: five sepals, five petals, numerous stamens, and especially a hypanthium (a structure under the flower, for example) consisting of the fused bottom parts of the petals, sepals and stamens.
  
  

Maloideae

• Apple blossoms.apple tree 1 image by Przemyslaw Koroza from Fotolia.com
  
  Taxonomists divide Rosaceae into a number of subfamilies, the exact number varying with the classification system used. The apple tree traditionally belongs to the subfamily Maloideae. Maloideae means literally "like the apple." Members of this subfamily are like the apple in the position of the ovary (below the other flower parts) and because they have a fruit called a pome, in which the hypanthium develops into edible fleshy tissue surrounding the ovary where the seeds develop.
  
  

Genus Malus

• The name Linnaeus gave to the apple did not endure. Miller gave it what is now its official name: Malus pumila. Borkhausen called it Malus domestica, often used in literature. Malus malus was also suggested, but after a lengthy controversy botanists decided to outlaw tautonyms, in which the genus name and the species name are the same.
  
  

Wild Apples

• Crab apples and wild apples also belong to the genus Malus. Writers sometimes call the common European wild apple by the Linnaean name Pyrus malus, though its proper name is Malus silvestris.