Pollen morphology of the Rosaceae of Western Canada

Abstract

This paper begins a systematic SEM and LM study of the pollen grains of the Rosaceae in Western Canada with genera Agrimonia, Alchemilla, Amelanchier, Aruncus, Chamaerhodos, and Crataegus. The above genera have tricolporate-tectate pollen grains in monads. Agrimonia gryposepala and A. striata have distinct striate sculpturing perpendicular to the colpus. Alchemilla occidentalis pollen is psilate except in the colpus area which is microechinate. The exine is thickened in the intercolpium. Aruncus Sylvester pollen is very small and exhibits a coarsely striate sculpture. Chamaerhodos erecta pollen has a characteristic protruding pore area with a fusiform operculum over the aperture. The sculpturing consists of patches of short ridges. Crataegus and Amelanchier pollen have pores with a characteristic equatorial bridge or flaps when open. Dimensions of the grains vary with degree of distension. Amelanchier alnifolia pollen exhibits geographic variability. Native North American Crataegus species: C. douglasii, C. rotundifolia and C. succulenta have pollen which exhibits morphological variability and requires more study. In the survey so far, surface sculpturing is the most distinctive feature and, in combination with characteristics of the pore area, seems to distinguish the types. A table of characters permits the pollen of most taxa studied to be identified using LM and SEM