Abstract

This thesis explores the seed germination of seven wildflowers native to sub-alpine ecosystems. Wildflowers are an essential functional group in native plant ecosystems. Also known as forbs, these plants offer a myriad of benefits in addition to being aesthetically pleasing. They provide habitats for anthropods and small mammals, support native pollinator populations, and grow well with other plant functional groups (especially perennial grasses and shrubs). Healthy plant communities make use of the limited resources in our native ecosystems, competing with invasive species that can otherwise dominate the landscape. Germination involves the transition from seed to an actively growing plant. Following germination, the seedling relies on stored energy reserves until it becomes as an autotrophic organism. Because germination is irreversible, it is the most vulnerable period of the plant lifecycle. Seeds of sub-alpine plants typically have complex dormancy-breaking requirements before growth begins. Therefore, understanding factors that influence the germination is essential to understanding propagation for horticultural use as well as timing of seedings for ecological restoration. The first chapter investigates the germination behavior of two co-occurring Asteraceae species across an elevation gradient. Mules ear (Wyethia amplexicaulis) and arrowleaf balsamroot (Balsamorhiza sagittata) seeds were collected at low, mid, and high elevation locations then subjected to a number of cold stratification treatment lengths (4-20 weeks) Both showed variance in germination behavior between elevation collection locations, with higher locations exhibiting a longer stratification requirement. The second study was developed to determine methods for breaking dormancy in five wildflower species for which existing literature is nonexistent or lacking. Delphinium nuttalianum (low larkspur), Delphinium exaltatum (tall larkspur), Frasera speciosa (green gentian), Polemonium foliosissimum var. alpinum (Jacob's ladder), and Mimulus grandifloras (monkey flower) were selected for this study because they all have the potential for use in horticulture and restoration ecology applications. Three species (low larkspur, tall larkspur, and green gentian) required long-term cold stratification to break dormancy. Jacob's ladder required physical scarification to break dormancy, and monkey flower required the combination of constant temperature with light exposure to germinate. These findings indicate that 1) six of seven species should be autumn-planted, and that propagation for horticulture use for five of the species is a lengthy process involving several months; 2) propagation of monkey flower seeds include strict temperature and light requirements; and 3) while seeds collected from different locations have the same type of dormancy-breaking requirements, variation in the degree of seed dormancy has ecological relevance.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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