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United States Department of Agriculture

Agricultural Research Service

Research Project: Development & Evaluation of Biological Control Agents for Invasive Species Threatening the Everglades & Other Natural and Mananged Systems

Location: Invasive Plant Research Laboratory

Title: Identity and origins of introduced and native Azolla species in Florida.

item Center, Ted
item Coetzee, Julie -
item Pemberton, Robert
item Purcell, Matthew -
item Hill, Martin -

Submitted to: Aquatic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 27, 2013
Publication Date: November 1, 2013
Citation: Madeira, P.T., Center, T.D., Coetzee, J.A., Pemberton, R.W., Purcell, M.F., Hill, M.P. 2013. Identity and origins of introduced and native Azolla species in Florida. Aquatic Botany. 111:9-15. 2013.

Interpretive Summary: Azolla pinnata, an exotic aquatic fern, is now in the northern Everglades and surrounding agricultural areas where it displays invasive characteristics. Both molecular and morphological tools indicate there are three A. pinnata subspecies and identify the Florida exotic as A. pinnata subsp. pinnata, the Australian subspecies. Specialist biological control agents are therefore most likely to be found in Australia. Molecular/ morphological tools also indicate the identified Florida native is A. caroliniana auct. non Willd., a hybrid species.

Technical Abstract: Azolla pinnata, an introduced aquatic fern, is spreading rapidly causing concern that it may displace native Azolla. It is now present in the Arthur R. Marshall Loxahatchee National Wildlife Refuge, the northernmost portion of the Florida Everglades. Because A. pinnata subspecies are native to Africa, Southeast Asia, and Australia, determining the actual geographic origin of the Florida exotic is important to the discovery of efficacious biological control agents. Both the exotic and native Azollas were examined using morphological and molecular criteria. Both criteria distinguished three A. pinnata subspecies with the Florida exotic matching the Australian A. pinnata subsp. pinnata. Molecular divergence between the A. pinnata subspecies indicates the three types should be considered separate species. The Florida native was characterized by both molecular and morphological methods as Azolla caroliniana. The discovery of a previously uncharacterized Ecuadorian Azolla, which appears to be a paternal ancestor of A. caroliniana, indicates that A. caroliniana is a hybrid species.

Last Modified: 8/27/2014
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