| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
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| Amaranthaceae | Alternanthera bettzickiana | Calicoplant, Parrotleaf | Disturbed areas, spread from horticultural use. | Native of South America. | 
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| Amaranthaceae | Alternanthera brasiliana | Brazilian Joyweed | Wet, disturbed areas. | Native of Central and South America. | 
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| Amaranthaceae | Alternanthera caracasana | | Disturbed areas. | Native of South America. Reported for Coastal Plain of SC, and in s. Coastal Plain of GA (Jones & Coile 1988) and for NC (FNA, K) and MD (K). | 
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| Amaranthaceae | Alternanthera flavescens | Yellow Joyweed | Hammocks, sandbars, coastal berms, shell mounds, coastal thickets. Often abundant and somewhat sprawling in understories of buttonwood hammocks and other shaded coastal areas sparsely to moderately saline-influenced. | Widespread in the FL peninsula, north to Brevard County; West Indies, s. Mexico (CAM, ROO, YUC), South America, the native distribution unclear, but seemingly native. The Clay County, FL record appears to be in error (A. Franck, pers. comm.; 2024). | 
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| Amaranthaceae | Alternanthera maritima | Seaside Joyweed, Beach Alternanthera | Coastal strands. | S. FL; West Indies; South America. | 
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| Amaranthaceae | Alternanthera paronychioides | | Disturbed areas, wet or dry flats, beaches. | Native of tropical America. | 
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| Amaranthaceae | Alternanthera philoxeroides | Alligator-weed | Floating in mats on the surface of the waters of blackwater rivers, sloughs, ditches, ponds, and in very moist soil of ditches and shores. | Native of tropical America. This plant is a serious weed of natural areas. Reported for s. IN by Bill Thomas (pers.comm., 2022). | 
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| Amaranthaceae | Alternanthera pungens | | Field edges, parking lots, other disturbed areas. perhaps only a waif at least northward. | Native of tropical America. Known from scattered locations in AL, FL, LA, NY, and TX (Clemants in FNA 2003b); native of tropical America. Reported for Sumter and Tift counties, GA (Carter, Baker, & Morris 2009). | 
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| Amaranthaceae | Alternanthera sessilis | Sessile Joyweed | Disturbed wet muck. | Native of the Tropics. First reported for SC by Nelson & Kelly (1997). Apparently now known in the Southeast from SC, FL, AL, MS, LA, TX (Brown & Marcus 1998) and GA (Jones & Coile 1988). | 
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