Identification of Eight Crabapples by Pollen Surface Sculpture1

Abstract

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.