Not considered a valid subspecies by Calflora, The Plant List, Flora Novae Angliae. Kew looks poorly-cited for this one, listing one source, "Index synonymique de la flore d'Afrique du nord."
Taxon 556361 was manually created on Aug 7, 2017, after this taxon swap, citing VASCAN.
Additionally (and maybe irrelevant), VASCAN was added as an iNat taxonomic authority after this taxon swap (Sept 11, 2017).
Unintended disagreements occur when a parent (B) is
thinned by swapping a child (E) to another part of the
taxonomic tree, resulting in existing IDs of the parent being interpreted
as disagreements with existing IDs of the swapped child.
Identification
ID 2 of taxon E will be an unintended disagreement with ID 1 of taxon B after the taxon swap
If thinning a parent results in more than 10 unintended disagreements, you
should split the parent after swapping the child to replace existing IDs
of the parent (B) with IDs that don't disagree.
I am confused...why is this taxon invalid but another is active?
Inactive taxon:
https://www.inaturalist.org/taxa/237892-Phragmites-australis-australis
Active Taxon:
https://www.inaturalist.org/taxa/556361-Phragmites-australis-australis