Sentence:  While seabeach <WSD>amaranth</WSD> is a fugitive annual, its habitat requirements are known; it is found on sandy ocean beaches, where its primary habitat consists of overwash flats at accreting ends of islands and the sparsely vegetated zone between the high-tide line and the toe of the primary dune on non-eroding beaches. This narrow habitat niche for seabeach <WSD>amaranth</WSD> is bounded by its relative intolerance of flooding in lower beach settings and competition with other plants in upper beach and dune settings. 
Meaning of the word marked with <WSD> tags:  Any of various herbs of the genus "Amaranthus".