Identification of Eight Crabapples by Pollen Surface Sculpture1

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.

Distinguishing Apple Clones and Cultivars by Surface Morphology and Pollen Physiology

“…Further characteristics of exine topography, such as pit and ridge shape, as demonstrated by Mass (4), Foggle (2, 3), and Martens and Fretz (6), may be utilized to classify species and cultivars; although in many cultivars such traits appear very similar. Grant (11) for instance, was unable to distinguish between subspecies of Zea mays on the basis of wall sculpture alone.…”

“…Reports of the effects of summer pruning on apple trees are varied. Summer pruning has been reported to reduce ( 1 ,7 , 17), to increase (8,12) growth (6,8) compared to dormant-pruned or unpruned controls. Utermark (20) reported that summer pruning reduced tree size, but Marini and Barden (12) concluded that summer pruning compared to similar dormant pruning could not control vegetative growth due to its stimulation of shoot growth in the following year.…”

“…and Vitis (4); between more related ones such as Prunus, Pyrus, and M alus (2,3); between Pyrus (5) and crabapple species (6); or between more closely related plant groups such as peach and nectarine (2,4). It obviously is more difficult to distinguish the cultivars of a given species (2,4) and still more so between clones of a cultivar because of the closeness of the relationship.…”

“…Several authors have remarked that the size and exine pattern of pollen are useful traits to distinguish fruit trees and other plant species (1,2,3,4,5,6). These studies were concerned with the differences between little-related genera such as Vaccinium…”

A Scanning Electron Microscope Study of Pollen of Phoenix (Arecaceae)1

“…Pollen morphology, sculpturing, and structure are useful in taxonomic studies from the family to the cultivar level (8,11,16,25). In this study, SEM was employed to determine if pollen grain morphology and structure could be employed to identify 'Received for publication June 19, 1981. This study was partially funded by a Statewide Critical Applied R e s e a r c h g r a n t t o th e s e c o n d a u t h o r .…”