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  • Author or Editor: Julia Martens x
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Abstract

Pollen specimens from 8 ornamental crabapples (Malus spp.) were compared using the scanning electron microscope (SEM) to determine if they, like apple cultivars, can be distinguished by pollen characters. All pollen grains were approximately equivalent in size, tricolpate, elliptical in shape, with tectate-perforate exine type. Exine riding was superficially similar among all 8 crabapples, but close examination revealed sufficient detail to distinguish between them. Pollen from 4 of the 8 crabapples, M. baccata var. mandshurica (Maxim.) C. K. Schneid., M. × purpurea (Hort. Barbier) Rehd. ‘Lemoinei’, M. × robusta (Carriere) Rehd. and M. Sargenta Rehd. possessed collared perforations. Among these M. baccata var. mandshurica and M. × purpurea ‘Lemoinei’ pollen had grains with parallel, unbroken exine ridging, while M. × robusta and M. sargentii grains commonly exhibited whorling of ridges. Spacing between exine ridges were wider on pollen grains of M. baccata var. mandshurica than on those of M. × purpurea ‘Lemoinei’, but M. × robusta and M. sargentii could not be distinguished using pollen characters alone. The remaining 4 crabapples lacked collared perforations and were further subdivided by perforation frequency. M. floribunda Siebold ex Van Houtte and M. × purpurea (Hort. Barbier) Rehd. pollen displayed a large number of simple perforations while pollen from M. × purpurea ‘Aldenhamensis’ and M. × zumi calocarpa (Matsum.) Rehd. yielded lower perforation frequencies. M. floribunda pollen had more closely spaced exine ridges than M. × purpurea. M. × purpurea ‘Aldenhamensis’ differed from M. × zumi var. calocarpa in that its pollen generally had larger perforations.

Open Access

Abstract

Leaf and terminal bud samples from 9 crabapples were examined using the scanning electron microscope (SEM) for the purpose of establishing consistent, identifying morphological detail Crabapples utilized in the study included: Malus × purpurea (Hort. Barbier) Redh.; M. × purpurea ‘Aldenhamensis’; M. × purpurea (Hort. Barbier) Rehd.; M. × purpurea ‘Aldenhamensis’; M. × purpurea ‘Lemoinei’; M. baccata var. mandshurica (Maxim.) C. K. Schneid.; M. floribunda Seibold ex Van Houtte; M. hupehensis (Pamp.) Rehd.; M. × robusta (Carriere) Rehd.; M. sargentii Rehd.; and M. × zumi var. calocarpa (Matsum.) Rehd. Overall, characters observed on terminal buds were less useful than leaf features. Only 4 species exhibited distinctive bud characters. Terminal bud surfaces of M. × robusta displayed unique networks of fibrillar wax. M. baccata var. mandshurica and M. × zumi var. calocarpa buds had defined stomatal structures. M. hupehensis exhibited singular invaginations in the bud epidermis. All crabapple leaves examined were hypostomatic, and all stomata appeared anomocytic. Stomatal characteristics most definitive for categorization were size and frequency. Adaxial and abaxial trichomes were similar in structure and were uniform among all species and cultivars. Observed types of abaxial cuticular striations were very useful as identification aides. Seven of the 9 crabapples could be characterized by foliage features alone.

Open Access