Freshwater Plants. Freshwater (also referred to as 'aquatic') plants are probably one of the most conspicuous features of the lakes, ponds, and streams of Acadia National Park. Approximately 80 species of freshwater plants can be found in the park, with an additional dozen species that are considered semi-aquatic shoreline species. Seven of these aquatic or semi-aquatic species are either currently listed or proposed for listing on Maine's Official List of Endangered and Threatened Plants, while about 30 others are considered 'locally rare.'