Pollen morphology and chromosome numbers of the family Plantaginaceae in North America

Abstract

Pollen grains of 28 Plantago and one Littorella species found in North America are described in detail and a key to their identification is presented. The general distribution, habitats, pollen production per anther, flower types (i.e. cleistogamous or chasmogamous) are given for each taxon and in addition the chromosome numbers are reported for 17 Plantago species and Littorella americana. Evidence is presented that Plantago fastigiata does not belong to the section Leucopsyllium. Fossil pollen grains of the Plantaginaceae, most likely to be found in any quantity in postglacial deposits of the Pleistocene epoch, are as follows: Plantago rugelii; P. cordata; P. eriopoda; P. macrocarpa; P. maritima; P. canescens; and Littorella americana.