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Modem taxonomists classify the genus Malus into 25 to 30 species and several subspecies (9, 25). Most species of this genus intercross freely, since there are no evident physiological and genetic barriers. Moreover, collections of Malus found in arboreta are classified inadequately and usually are grown from seed which is generally a result of interspecific or intraspecific hybrids (9).
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S. S. Korban (1986) studied this question.
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