Abstract Detail

Floristics & Taxonomy

Sicking, Elizabeth [1], Metzgar, Jordan [2].

Characterizing the ecological preferences and geographic distributions of the Opuntia humifusa complex in Virginia.

Cacti are New World plants distinguished by their variety, xeric adaptations, and colorful flowers which make them well-loved plants in settings ranging from natural areas to home gardens. Although typically associated with deserts and other environments with low precipitation, native cactus species can be found in 46 of the contiguous states in the USA, including Virginia. The prickly pears (Opuntia) consist of over 150 species and have agricultural and medicinal uses throughout the world. They are characterized by rampant hybridization and polyploidization, making them an often taxonomically difficult system. Originally treated as a single species, the Opuntia humifusa complex consists of eight taxa distributed throughout the eastern United States. Three tetraploid members of the Opuntia humifusa complex occur in Virginia: O.mesacantha subsp. mesacantha, O. cespitosa, and O. humifusa. We clarified the range and distribution of each of these three species within the state of Virginia using a combination of herbarium specimens, iNaturalist observation data, and field collections. Opuntia mesacantha subsp. mesacantha is found primarily in eastern Virginia within the coastal plains and O. cespitosa is found in western Virginia in the Ridge and Valley region. Opuntia humifusa is a hybrid of O. mesacantha and O. cespitosa, and is found throughout the state. Despite its more widespread presence in Virginia, O. humifusa has the smallest overall distribution of the three species. Its success in Virginia may be due to an intermediate or novel habitat within the state that it has colonized to avoid competition from its parents. Our research will also identify the ecological preferences and suitable habitat for all three species. We will also assess possible conservation concerns for each species by documenting potentially isolated disjunct populations and determining if O. cespitosa qualifies as a state listed rare plant. Citizen science is an important aspect of our project and can greatly expand our sampling, as cacti are often under-collected and under-represented in herbaria. Our use of an iNaturalist project also allows us to educate native history enthusiasts in Virginia about these little known species and promote increased conservation efforts. By providing basic biodiversity information on these species, our study may assist broader research on conservation biology and the mechanisms involved in polyploidization.

1 - Virginia Tech Massey Herbarium, Biological Sciences, MC0406, Blacksburg, VA, 24061, USA
2 - Virginia Tech, Biological Sciences, 926 W. Campus Dr, MC 0406, Derring Hall 2119, Blacksburg, VA, 24061, United States


Presentation Type: Oral Paper
Number: F&T I010
Abstract ID:315
Candidate for Awards:None

Copyright © 2000-2022, Botanical Society of America. All rights reserved