המועדפים של pastabaum

🇨🇿 Tytéž rostliny jako pozorování 208935897 po několika nočních mrazech (ten poslední -5°C, tady navíc u vody). Stonky se rozpadají na kašovitou hmotu. Kéž by mrazu šlo využít na boj s nimi.
🇬🇧 The same plants as observation 208935897 after several frosty nights (the last one -5°C, here the effect amplified by nearby water). The stalks disintegrate into a mushy mass. If only the effect of frost were useable in fighting with them.

This taxon is part of a group of apomictic pseudogamous species. This group is traditionally called P. collina agg. In POWO the name P. collina is restricted to a taxon that has a limited distribution in Russia. The specific taxon of P. collina agg. in eastern Austria was variably named (leucopolitana, wibeliana, wiemanniana), but all those names are not valid for this area. The taxon of P. collina agg. in eastern Austria could be identical with the east European P. thyrsiflora or it is a distinct species.
Diagnostic features of this taxon of the Potentilla collina-group (partly valid also for related species):
perennial; stem ascending, normally 15-30 cm high; ground leaves normally with 5 leaflets, withering when flowering, but occur again later in the year (August) when a second phase of flowering after rain could happen; stipules and stem hairy; stipules often incised, but not until the bottom; stem leaves quite variable with 3 to 6 teeth on each side of each leaflet, above sparsely hairy, but beneath more or less densely hairy with crispate and tufted hairs (not that densely hairy than P. argentea s.l.), the margins of the leaves are not rolled back (like in P. argentea); the inflorescence is quite numerous-flowered; the petals are normally slightly longer or at least as long as the sepals.

Possibly???
About 5.5-6 ft tall. Note the gaps between the female spike and the male spike are quite variable, a field characteristic that was pointed out to me by @pastabaum.
This roadside pond is an old quarry pond. Soil is sand and gravel.

1. Trifolium campestre

Together with:

1. Trifolium repens
2. Trifolium pratense
3. Trifolium dubium
4. Trifolium hybridum

Honorable mentions:
(6) Medicago lupulina (not Trifolium but looks similar)

Not in the picture but only a few meters away:
[7] Trifolium ochroleucon (?!)
[8] Trifolium arvense

Growing in a newly reconstructed retention area with seemingly poor soil and low vegetation.

Also RIP: Bolboschoenus laticarpus

Fruchtstiele dicht mit kurzen Drüsen besetzt; bis zu 9-blütig; Basallappen der Laubblattspreite nicht oder kaum überdeckend; Laubblattstiel mit kurzen Drüsen besetzt, wobei die Drüsenstiele nur 2-5 x so lang sind wie das Drüsenköpfchen (auf den letzten zwei Fotos kann man dies erahnen).

Sehr ähnlich und leicht zu verwechseln mit Melilotus officinalis, jedoch eine Art der Feuchtlebensräume!
Flügel so lang oder kaum länger als das Schiffchen (bei M. officinalis deutlich länger); Fruchtknoten und Früchte schwach behaart (bei M. officinalis völlig kahl); reife Früchte undeutlich netzrunzelig (bei M. officinalis deutlich querrunzelig).
Für M. altissimus und M. officinalis gilt gleichermaßen: untere Nebenblätter oft mit 1-2 Zähnen, obere schmal-linealisch ohne Zähne; Fiederblättchen der unteren Stängelblätter meist deutlich breiter als die der oberen.
Letzte zwei Bilder: Blüten und junge Früchte im Vergleich von M. altissimus (links) und M. officinalis (rechts).

Identification based on the shape and size of the leaves and the presence of small hairs of 1-2 cells long on the abaxial surface.
Pictures of hairs taken from the microscope on the 23rd of June 2022.

Identification based on the size of the impressive height of the plant, on the shape and great size of the leaves as well as their thickness, and on the long hairs observable on their abaxial surface.
Bike for scale.