Stellaria pubera and Stellaria corei
Present taxonomy would place a Stellaria pubera with:
(1) sepals as-long-as or longer than the petals; and
(2) sepals whose underside/abaxial surface is smooth/bald/glabrous
as Stellaria corei, originally described as a subspecies of Stellaria pubera.
However, it is apparent (see iNat observations below) that individuals of Stellaria pubera can have:
1) long pubescent sepals
2) long glabrous sepals
3) short pubescent sepals
4) short glabrous sepals
How can this be?
That being said, only 1 observation has been found (as of 23 May 2021) of a Stellaria pubera with pubescent sepals that are longer than the flower petals [this may be a triploid]. I therefore tentatively suggest that
What to do with the triploids? A situation that perplexes current taxonomy.
Below are iNaturalist observations of Stellaria pubera
1) Pubescent and Short Sepals
https://www.inaturalist.org/observations/75730401 pubescent short sepals
https://www.inaturalist.org/observations/75581210 pubescent short sepals
https://www.inaturalist.org/observations/75501455 pubescent short sepals
https://www.inaturalist.org/observations/75367119 pubescent short sepals
2) Glabrous and Short Sepals
https://www.inaturalist.org/observations/75620153 glabrous short sepals
https://www.inaturalist.org/observations/75432600 glabrous short sepals
https://www.inaturalist.org/observations/75309895 glabrous short sepals
https://www.inaturalist.org/observations/75367619 glabrous short sepals
https://www.inaturalist.org/observations/75823835 glabrous short sepals
https://www.inaturalist.org/observations/77168514 glabrous short sepals
https://www.inaturalist.org/observations/77386917 glabrous short sepals
https://www.inaturalist.org/observations/77702361 glabrous short sepals
https://www.inaturalist.org/observations/78464955 glabrous short sepals
https://www.inaturalist.org/observations/78925219 glabrous short sepals
https://www.inaturalist.org/observations/79358374 glabrous short sepals
https://www.inaturalist.org/observations/79594252 glabrous short sepals
https://www.inaturalist.org/observations/80194371 glabrous short sepals
3) Pubescent and Long Sepals (nearly-as-long-as or longer than the flower petals)
https://www.inaturalist.org/observations/75264055 pubescent very long sepals ***
https://www.inaturalist.org/observations/75371414 pubescent long sepals
https://www.inaturalist.org/observations/75369222 pubescent long sepals
https://www.inaturalist.org/observations/75365581 pubescent long sepals
https://www.inaturalist.org/observations/75603724 pubescent long sepals
https://www.inaturalist.org/observations/76389550 pubescent long sepals
https://www.inaturalist.org/observations/76261689 pubescent long sepals
https://www.inaturalist.org/observations/77204533 pubescent long sepals
https://www.inaturalist.org/observations/77304357 pubescent long sepals
https://www.inaturalist.org/observations/77392727 pubescent long sepals
https://www.inaturalist.org/observations/77747127 pubescent long sepals
https://www.inaturalist.org/observations/77942031 pubescent long sepals
https://www.inaturalist.org/observations/78538457 pubescent long sepals
https://www.inaturalist.org/observations/78562824 pubescent long sepals
https://www.inaturalist.org/observations/78930613 pubescent long sepals