Abstract
Modern pollen grains from several species of Abies, Picea and Pinus occurring mainly in the Rocky Mountain region of the United States and Canada were examined using the scanning electron microscope. Distinguishing characteristics for the species were found using systematized observational and photographic methods on extensive collections. Preparation of the samples included acetolysis, critical-point drying to preserve three-dimensional morphology, and carbon-gold coating. The technique employed in preparing the pollen samples is outlined in detail in this paper. Species distinctions were based on types of morphological structures rather than on measurements of the grains or their parts; however, several subjective determinations of shape and proportion proved useful in distinguishing certain species. Pollen grains of Abies grandis, A. amabilis and A. lasiocarpa were found to differ in the morphology of the triradiate streak. Picea glauca and P. sitchensis differ in cappula morphology and P. engelmannii shows distinctive bladder proportion and placement. Pinus ponderosa differs from P. contorta on the basis of cappula morphology. Pinus monticola and P. albicaulis can, at the same time, be singled out from the other pines studied and distinguished one from the other by a combination of a cappula and cappa characteristics. Pinus cembroides is distinguished from the other pines by its characteristic cappa and P. edulis by shape, proportion and attachement of its bladders. Although Pinus monophylla showed no single distinctive morphological feature, it can be separated from the other pines studied by a process of elimination based on several characteristics.
Published Version
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