Evaluating Herbaceous Perennials for Landscape Performance and Pollinator Behavior in North-Central Texas

Kara Bailey

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ag Science and Natural Resources

Date of Award

Fall 2022

Abstract

Urban areas are increasing with the growing human population, which in turn decreases the resources available for pollinators. Perennial plants can be used in urban settings for visual appeal while also providing for various pollinator species. However, some species of perennials have neither been evaluated for landscape performance in north-central Texas, nor how they may provide forage for pollinators. In this study, 20 species of perennial plants were evaluated based on physical and physiological measures of plant performance, along with documentation of pollinator visits. Weekly, each plant was counted for bloom number, scored based on visual appeal, and observed for 60s to count and identify pollinator visits. Monthly, two species, Salvia guaranatica ‘Black and Blue’ and Malvaviscus arboreus drummondii 'Pam Puryear', were evaluated for stomatal conductance, net photosynthesis, leaf temperature and relative humidity. These two species were also evaluated once using a light response curve, comparing net photosynthesis rates at irradiance levels between 0 and 1500 W·m-2. The top 3 plants, based upon average highest overall score, were Salvia farinacea ‘Henry Duelberg’, Salvia farinacea ‘Augusta Duelberg’, and Salvia × sylvestris ‘Mainacht’. Each species supported a specific type of pollinator. Perovskia atriplicifolia supported the broadest range of pollinators, visited regularly by more than 8 different species. Foeniculum vulgare had the highest number of pollinator visits. To support bumblebee populations, it is recommended to plant Salvias and lantanas. To support other various Hymenopteran, Foeniculum vulgare and Pycnanthemum muticum should be planted. Conoclinum coelistinum and Pycnanthemum muticum are recommended to support Lepidopterans and dipterans. Echinacea purpurea, Phlox paniculata ‘John Fanick’, and Echinacea angustifolia had the highest SPAD readings and are recommended for north-central Texas. Comparing the two light response curves, Malvaviscus arboreus drummondii 'Pam Puryear' had higher net photosynthesis, suggesting it can perform better in high levels of light and should be planted in full sun for maximum performance The species that can be used in urban environments for ornamental purposes while also supporting pollinator populations in north-central Texas are Salvia farinacea 'Augusta Duelberg', Salvia farinacea 'Henry Duelberg', Conoclinum coelistinum, Persovskia atriplicifolia, and Salvia ‘Indigo Spires’.

Advisor

Derald Harp

Subject Categories

Agriculture | Life Sciences

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