This post is simply a place to collect various notes and random information relating to the beach naupaka complex for my own future reference and to help guide my decisions as I identify these plants.
There was a taxonomic change made for Scaevola taccada by Kew and the Kew taxonomy is used by iNaturalist. S. taccada has apparently been split into S. plumieri and S. Sericea. S. taccada is now a synonym for S. plumieri. S. plumieri and S. sericea are said to have precedence over S. taccada. I would note that I was confused and had the temerity to write to Kew and ask about the change, and to my surprise Kew wrote right back:
"The references [to the taxon change] can be found here:
http://plantsoftheworldonline.org/taxon/urn:lsid:ipni.org:names:384339-1#bibliography
What you call Scaevola taccada with white fruits is probably now correctly known as S. sericea:
http://plantsoftheworldonline.org/taxon/urn:lsid:ipni.org:names:30200356-2
Regards, Rafaël Govaerts
Senior Content Editor – Plant & Fungal Names, Biodiversity Informatics & Spatial Analysis, Royal Botanic Gardens, Kew, Jodrell Laboratory, Kew Road, TW9 3DS, United Kingdom"
The Kew herbarium sheet for S. plumieri http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:384294-1 notes "Fruit blue or black, sub-globose, 10–15 mm. across, very fleshy, drying warty."
The City of Sanibel Vegetation Committee has a good publication on distinguishing Scaevola plumieri:
"Scaevola plumieri, is an erect to trailing, herbaceous evergreen shrub which can grow to four feet in height. These plants often form dense clumps, and the alternate, glossy green, thick leaves cluster near the branch tips. Inkberry prefers a dry, sandy habitat and is an ideal plant for the beach zone as it is salt and drought tolerant. The trailing succulent stems help to trap sand and acting as a beach stabilizer. Although, this plant is most often found near the beach, it will grow in a variety of soils. Inkberry tolerates full sun, flowers most of the year, and its dense growth provides excellent shelter for birds and mammals. The small, fan-like, whitish colored flowers with a yellow throat grow in clusters among the terminal leaves, followed by glossy black fruits eaten by birds."
The publication goes on to contrast the inkberry to the non-native Scaevola, referred to as Scaevola taccada in the publication, "The non-native inkberry.. is a weedy, fleshy variety, forming dense mounds of shiny green leaves. The white half-flower is followed by a white berry. "
Source: https://www.mysanibel.com/content/download/23790/147551
Another note came in from Robert Archer at the South African National Biodiversity Institute:
"The names S. sericea and S. taccada have been very frequently been debated over the last 70 years or more. This all depended on a strict application of the code at the time or a less strict application. So much so that an effort has been made to conserve the name S. taccada as it was the most frequently used name at the time. This application was not accepted as instead the code was adjusted and by using this name as an example (Art 41.4 ex 10 (https://www.iapt-taxon.org/nomen/pages/main/art_41.html?)). Therefore as I am not aware of any new or recent (re-)application of the names and as the references on POWO are not very recent or not available to me, or I did not try to find it. The statement that S. taccada is now a synonym of S. plumieri needs to be clarified and till then cannot be followed by iNat. Apart from the white fruit, the thicker stems with the prominent leaf scars and the rounded leaves with its prominent midrib and venation distinguish this species. The type of S. sericea and hence S. taccada ssp. sericea when it was published by St John in 1960 was from the "Savage Island" (Niue). Would this be worth keeping in the Inat database. Probably not."
https://www.inaturalist.org/observations/13343808
The note at IAPT states in example ten:
"Scaevola taccada was validly published by Roxburgh (Hort. Bengal.: 15. 1814) solely by reference to an illustration in Rheede (Hort. Malab. 4: t. 59. 1683) that is associated with a description of a species. Because the same illustration was cited in the protologue of the earlier name Lobelia taccada Gaertn. (Fruct. Sem. Pl. 1: 119. 1788) and the two names apply to the same species, S. taccada is treated as a new combination, S. taccada (Gaertn.) Roxb., not as the name of a new species, even though in Roxburgh’s protologue there is no reference, either direct or indirect, to L. taccada."
As of the writing of this edit of this post (May 2019) other databases do not accept S. sericea:
http://www.tropicos.org/Name/14600036?tab=acceptednames
http://theplantlist.org/tpl1.1/record/tro-14600036
https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=505045#null
As iNaturalist follows Kew and a curator could run the swap at any time, I see value in at least keeping the white fruit species from being merged into S. plumieri by IDing them as S. taccada subsp. sericea. For now I consider that the key photographic distinction may have to be the fruit color. White will apparently be S. sericea, black or blue will apparently be S. plumieri. Note that as of the writing of this post, the taxon swap has not yet occurred in iNaturalist, thus there is no option at present to ID the white fruited S. taccada as S. sericea, only as S. taccada ssp. sericea. S. plumieri, on the other hand, is an available ID in iNaturalist. I suspect there is also the matter yet to be sorted out that Pacific island beach naupaka does not have leaves covered with fine, silky hairs (sericea), but is glabrous.
Perhaps someone will publish a paper against the 2012 resurrection of S. sericea and retain S. taccada as per the IAPT code adjustment.
As a post-script R. Archer notes that identifications should only be made S. taccada and not the subspecies:
"[That S. sericea is not listed as accepted] is because of two issues. The first is the nomenclature issue, where it is established in the above-mentioned websites that S. taccada is the accepted name with C. sericea as a synonym. Note that the Theplantlist.org is the precursor for the Kew POWO. The second issue is taxonomy. Are there more than one subspecies or even varieties? The ssp. sericea is an attempt by St. John in 1960 published this as well as other varieties but he presumably did not follow up to publish a revision of the group. The presence of hair is obviously one character but as you mentioned it seems to vary. Therefore the best practice would be to use Scaevola taccada only."
"Taxonomy is described sometimes as a science and sometimes as an art, but really it’s a battleground."
- Bill Bryson, A Short History of Nearly Everything
