Examining Morphological and Habitat Variation within Stenanthium gramineum (Eastern Featherbells, Melanthiaceae)

Hannah Cook, M.S. Candidate, Biology, Western Carolina University

Stenanthium gramineum (Ker. Gawler) Morong, commonly known as “Eastern Featherbells” is a perennial herb that occurs in the Southern Appalachians and more broadly throughout the midwestern, southwestern and eastern U.S. Historically, this species has been under-studied, and is taxonomically unclear. Currently, two varieties are recognized, distinguished in part by habitat differences. Stenanthium gramineum var. gramineum is considered a rock-outcrop species throughout its large range of the southwestern, midwestern and eastern U.S., but also occurs on grassy balds and serpentine barrens of the Southern Appalachians. Stenanthium gramineum var. robustum (S. Watson) Fernald is said to be found in bogs and wet meadows; it is listed as endangered and threatened throughout its native range of the eastern U.S., causing need for special attention. A third variety, S. gramineum var. micranthum Fernald, is not currently recognized, but was described on the basis of its unique granitic dome rock outcrop habitat. It appears to be extremely rare, and seems to be exclusive to a small range within the eastern U.S. In sum, each of these varieties occupy unique, sensitive habitat, and potentially could be recognized as separate species, as they may display discrete differences in morphological characteristics. The goal of this project was to investigate morphological and ecological characteristics of the three S. gramineum varieties in order to clarify their taxonomy and aid conservation. During the summer and fall of 2019, I located seven flowering populations of two taxa (var. gramineum and var. robustum) in the Southern Appalachians, measured morphological and environmental characters in the field and collected samples for morphological, leaf anatomical and pollen analysis. To expand the dataset, I measured multiple morphological characters on herbarium specimens from throughout the ranges of each taxon. Multivariate analysis will be performed to determine whether two or more distinct entities can be discriminated based on these data. This study should clarify the taxonomic status of var. robustum and identify the most reliable characters used to define it, and should facilitate identification and conservation of this rare taxon.

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