I apologise for being to brief above.
I see there were also correct form 'Pisum sativum subsp. elatius' in iNaturalist but it was supressed in favour of the incorrect one, with 'elatium'. This word does not exist in Latin.

There exist a common (positive) adjective 'elatus' - 'elata' - 'elatum' (in masculine, feminine, neutral genders, respectively) meaning 'high'. There is also a comparative adjective meaning 'higher', which is 'elatior' - elatior' - 'elatius' in masculine, feminine, neutral genders, respectively. The latter is our case - the generic name 'Pisum' is of the neutral gender, so the species or subspecies epithet is coordinated to it in gender and is 'elatius'. (All the Latin words mentioned above in singular and in the nominative case, as should be in the botanical nomenclature. Also note that positive and comparative adjectives are considered different specific epithets, so 'elatius' is not a form of 'elatum' but a different word. We more often see comparative adjectives in botanical nomenclature in more familiar masculine and feminine genders, which in our case would coincide in, 'elatior').

Although the above grammatic argument is decisive, I would like to point out that the correct form 'Pisum sativum subsp. elatius' is invariably used in rich literature on wild peas (leaving aside other systematic treatments using other ranks or names, such as Pisum elatius, Pisum syriacum, Pisum sativum subsp. biflorum, Lathyrus oleraceus subsp. biflorus etc.)

The full form, with authorities, is Pisum sativum L. subsp. elatius (Bieb.) Aschers. et Graebn. In this sense, according to the at present most broadly used compromise system (Maxted, N. Ambrose, M. 2001. Peas (Pisum L.). In: Plant genetic resources of legumes in the Mediterranean. Eds. Maxted N. and S.J. Bennett. Kluwer Academic Publishers. The Netherlands. Chapter 10, pp 181-190)
it embraces all genuine wild representatives of the species Pisum sativum, being so opposed to the cultivated subpecies Pisum sativum subsp. sativum.

Thank you for considering the case,
While the subspecies concept in botany is not so well defined and overall worldwide databases still contain some non-optimal solutions and even erroes, this specific case is quite clear.

According to the currently most used system of the genus Pisum (I'm afraid not available online):
Maxted, N. Ambrose, M. 2001. Peas (Pisum L.). In: Plant genetic resources of legumes in the Mediterranean. Eds. Maxted N. and S.J. Bennett. Kluwer Academic Publishers. The Netherlands. Chapter 10, pp 181-190.
the species Pisum sativum L. is considered to have two subspecies:
Pisum sativum subsp. sativum , including cultivated peas
Pisum sativum subsp. elatius (Bieb.) Aschers. et Graebn. in the broad sense , embracing all genuine wild populations of the species (not sometimes occurring feral peas).

This system is not without drawbacks since it makes P. sativum subsp. elatius paraphyletic (since P. sativum subsp. sativum was derived from it), but is very convenient practlically. There is a leading diagnostic character: P. sativum subsp. elatius has spontaneously dehiscing pods providing ballistic seed dispersal for several metres, that allows a wild plant to disperse. P. sativum subsp. sativum has non-dehiscing pods allowing harvesting. In this situation of disruptive selection the former subspecies cannot be cultivated while the latter cannot exist in nature for long. (Other diagnostic characters of P. sativum subsp. elatius are seed dormancy, sometimes for several years, and as a rule tuberculated seed cover).

Besides, this sytem best fits the concept of iNaturalist which suggest registry of wild organisms. Now we have an explicitly wild taxon, P. sativum subsp. elatius. Importantly, it includes very local and rare plants , while the cultivated peas are common and widespread. If P. sativum subsp. elatius were subsumed to P. sativum, (i) the rare observations of the former would look like those of cultivated (or rare feral) plants, which users forgot to mark as such and (ii) could encourage users to register cultivated peas. Retaining P. sativum subsp. elatius will stress uniquity of genuine wild pea populations and encourage their registry in iNaturalist. So, please, retain this subspecies.

P.S. Profound taxonomical changes in pulses are not excluded in future, since recent molecular phylogenetic studies suggested to subsume the genera Pisum and Vavilovia to Lathyrus and Lens to Vicia. But at least a long time is necessary for botanist to accept this view, so at present it is too early to go into more details.

elatius, of course

https://www.inaturalist.org/taxon_changes/32265

@beetledude could you correct the misspelling?

@oleg_kosterin yes, in the future we should consider the possibility to follow the latest phylogenetic novelties that lead to the inclusion of Pisum in Lathyrus but let's keep subsp. elatius (the wild pea) separated from the nominal subspecies (the cultivated pea. In my opinion, since the two taxa seem to be well distinct, at least here in the Mediterranean, we should avoid to follow the taxonomic backbone for botanical names in which the two taxa are included in the species.

@mftasp thank you