- "Wild apple" redirects here. In Australia, this may refer to the unrelated Pouteria eerwah.
Malus (pronounced /ˈmeɪləs/), the apples, is a genus of about 30–35 species of small deciduous trees or shrubs in the family Rosaceae. Other studies go as far as to say it includes 55 species including the domesticated Orchard Apple, or Table apple as it used to be called (M. domestica, derived from M. sieversii). The other species and subspecies are generally known as "wild apples", "crab apples", "crabapples" or "crabs".
Apple trees are small, usually 4–12 m tall when full grown. The leaves are 3–10 cm long, positioned opposite from each other. They have a simple shape with a saw-tooth edge. The flowers come from corymbs, and have five petals, which may be white, pink or red, with usually red stamens that produce lots of pollen, and an ovary which is below them. Flowering takes place in the spring after 50–80 growing degree days (this varies a lot according to subspecies and cultivar). Apples need to be pollinated from one tree to another by insects (typically bees, which freely visit the flowers for both nectar and pollen). All are unable to pollinate themselves, and (with the exception of a few specially developed cultivars) self-pollination is impossible, making pollinating insects required.
For Malus sylvestris domestica, see Apple. The fruit of the other species is not an important crop in most areas because they are very sour and (in some species) very like wood, and are rarely eaten raw for this reason. However, crabapples are an excellent source of pectin, and their juice can be made into a ruby-coloured jelly.Some kinds of crab apples make good applesauce.
Crabapples are widely grown as trees for the pleasure of their appearance, grown for their beautiful flowers or fruit. There are cultivars selected for these qualities and for resistance to disease.
They are also used as tree for pollinating food apple trees in apple orchards. Varieties of crab apple are selected to bloom at the same time as the apple trees in an orchard, and the crabs are planted every sixth or seventh tree, or limbs of a crab tree are grafted onto some of the apple trees. See also Fruit tree pollination.
Because of the many blossoms and small sized fruit, crab apples are popular for use in bonsai. Because the trees are small due to the needs of the hobby, but still show the abundant fruit bearing of full-sized crab apples, it is important to thin out fruit so that trees do not stress themselves.
- Sunset Western Garden Book, 1995:606–607
- Phipps, J.B. et al. (1990). "A checklist of the subfamily Maloideae (Rosaceae)". Can. J. Bot. 68: 2209. doi:10.1139/b90-288.
- Rombauer, I.; Becker, M. R., & Becker, E. (2002) . All About Canning & Preserving (The Joy of Cooking series). New York: Scribner. p. 72. ISBN 0-7432-1502-8.
- Cornell University, Department of Horticulture Apple Tree Rootstocks Ecogardening Factsheet #21, Summer 1999
- Fraser, Ana. "Traditional Uses of Wood." 22 Aug 2005. 17 July 2008. http://www.the-tree.org.uk/TreeCultivation&Uses/Uses/usesofwood.htm#Apple%20wood
- Germplasm Resources Information Network: Malus
- Flora of China: Malus
- Virginia Cooperative Extension – Disease resistant crabapples
- Ontario Ministry of Agriculture and Food – Crabapple pollenizers for apples
- The PRI disease resistant apple breeding program: a cooperative among Purdue University, Rutgers, and the University of Illinois.
- Germplasm Resources Information Network: Diab