Editing Alternanthera (section)

==Description==
These are annual or perennial herbs or [[subshrub]]s. While some of the better-known species are [[aquatic plant]]s, most are terrestrial.<ref name=tan/> They take many forms, from prostrate to erect to floating. The leaves are oppositely arranged. The [[inflorescence]] is a spike or a rounded head occurring in the leaf axils or the ends of branches. The flowers have 5 [[tepal]]s. There are 3 to 5 [[stamen]]s which are fused into a rim at the bases, and 5 pseudostaminodes, appendages between the stamens that are not true [[staminode]]s. The fruit is a [[Achene|utricle]] containing one seed.<ref name=fna/>

The genus ''Alternanthera'' contains both [[terrestrial plant|terrestrial]] and [[aquatic plant|aquatic]] species. The [[photosynthesis|photosynthetic]] pathway varies in this genus: Some species undergo [[C3 carbon fixation|C<sub>3</sub> carbon fixation]], one clade of 17 species has acquired the [[C4 carbon fixation|C<sub>4</sub> pathway]], and yet other species have an intermediate C<sub>3</sub>-C<sub>4</sub> pathway.<ref name="SageSage2007">{{cite journal |last1=Sage |first1=R.F. |last2=Sage |first2=T.L. |last3=Pearcy |first3=R.W. |last4=Borsch |first4=T. |title=The taxonomic distribution of {{C4}} photosynthesis in Amaranthaceae sensu stricto|journal=American Journal of Botany |volume=94 |issue=12 |year=2007 |pages=1992–2003 |issn=0002-9122 |doi=10.3732/ajb.94.12.1992|pmid=21636394 }} {{open access}}</ref><ref name=san/><ref name=chin>Chinthapalli, B., et al. (2001). [https://link.springer.com/article/10.1023/A:1010981807667#page-1 Phospho''enol''pyruvate carboxylase purified from leaves of C<sub>3</sub>, C<sub>4</sub>, and C<sub>3</sub>-C<sub>4</sub> intermediate species of ''Alternanthera'': Properties at limiting and saturating bicarbonate.] ''Photosynthetica'' 38(3), 415-19.</ref>