BOT 360F - Families of Vascular Plants

ROSACEAE: Maloideae
Malus spp.

Malus (apple) includes about 55 species of the north temperate zone. Some species (e.g. M. coronaria, below) are important as wildlife food sources and cover, while others are important as decorative plantings ("flowering crabapples") or for their fruit (see below).

Photo: M. Ferguson © Royal Ontario Museum 1998

"Malus domestica," the cultivated apple, appears to have originated in Central Asia, and to have been carried into Europe by traders and others prior to Roman times. Malus domestica comprises more than 2000 cultivars, each one selected and preserved by humans by vegetative propagation (grafting, etc.) from one generation to the next. This is required because cultivated apples are obligate outcrossers, and so the offspring of any given tree are unlikely to resemble that tree in its desirable characteristics. Meiosis, gametophyte development (no matter how abbreviated), and gamete fusion intervene between generations.

Apples are the most important temperate zone fruit, thanks to their flavor and to the sugars invested in their flesh as part of the endozoochorous seed dispersal syndrome. They are eaten fresh or dried, cooked, or pressed to make juice or cider which, in turn, can be fermented ("hard cider") and distilled (e.g. calvados). Pollan (2001) describes how John Chapman ("Johnny Appleseed") collected apple seeds from cider mills in western Pennsylvania during the early 19th c. and then carried them to the Ohio country where he planted a succession of orchards from which settlers were able to obtain planting stock for their own orchards, and from which new varieties could be discovered and propagated.

Malus coronaria (L.) Miller is the native wild apple of eastern North America. It is a polymorphic complex of diploids, triploids, and tetraploids. Polyploid M. coronaria individuals reproduce asexually (Dickson 1995). Hybrids between ploidy levels can persist and proliferate, with the result that many such asexually reproducing genotypes have been named as species in the past.

Photos: R. Presgrave, © 2000, Royal Ontario Museum.


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