Pseudoleskeella is a genus of mosses that I revised taxonomically. This paper is a companion to the revision and explains how I recognized that several features are all aspects of a more united developmental system. The different species of Pseudolesk . . .

Pollen presentation theory (PPT) allows for a re?examination of some classic themes in pollination biology. Here, we outline its implications in the context of bee? and bird?adapted species of Penstemon and Keckiella (Scrophulariaceae). PPT models the . . .

Individual bees often prefer flowers of the same species that they are already foraging on, and other individual bees prefer other flowers. This "floral constancy" has classically been explained as a learned behavior by which bees avoid wasting time s . . .

Floral phenotypes may be as much the result of selection for avoidance of some animal visitors as selection for improving the interaction with better pollinators. When specializing on hummingbird‐pollination, Penstemon flowers may have evolved to impr . . .

In certain angiosperm genera, closely related species have diverged from one another to converge on different pollination syndromes, whereas species with intermediate phenotypes are rare or absent. Convergent conformity to syndromes implies the existe . . .

Speciation involves the formation of reproductive isolating mechanisms such as a difference in pollinators, incompatibility between pollen tubes and stylar tissue, hybrid seed abortion, or poor growth of hybrid seedlings. We studied reproductive isola . . .

In North America and Europe six species of Pseudoleskeella Kindb.(Leskeaceae) are recognized: P. nervosa (Brid.) Loeske, P. sibirica (Arn.) P. Wilson & Norris, comb. et stat. nov.(based on Leskea nervosa (Brid.) Myr. var. sibirica Arn.), P. tectorum ( . . .

Few studies have surveyed the insects visiting flowers at many sites and for many related species. Calochortus, a genus of about 60 species with its center of diversity in California, has flowers with a wide range of appearances. Insects visiting Calo . . .

Certain floral characteristics are associated with specific pollinators. Hummingbird-pollinated flowers are usually red, lack a landing platform, lack nectar guides, and contain a high amount of dilute sucrose-rich nectar. Here we test hypotheses conc . . .