(2841) Lechea verticillata Willd., Sp. Pl. 1: 495. Jun 1797 [Angiosp.: Elatin.], nom. cons. prop. Typus: Ind[ia], 1791, Klein, right-hand plant (B-W barcode B -W 02396 -01 0!), typ. cons. prop. Many authors (e.g., Backer in Van Steenis, Fl. Males., Ser. 1, 4: 203–206. 1951; Verdcourt, Fl. Trop. E. Africa, Elatinaceae: 1–5. 1968; Sohmer in Dassanayake, Revis. Handb. Fl. Ceylon 1: 424–427. 1980; Verdon in Jessop, Fl. Centr. Australia: 228–229. 1981) have attributed the name Bergia ammannioides to Roth (Nov. Pl. Sp.: 219. 1821), while others such as Thiselton Dyer (in Hooker, Fl. Brit. India 1: 250–252. 1874), and Backer & Bakhuizen van den Brink (Fl. Java 1: 205. 1963) have adopted B. ammannioides Roxb. (Hort. Bengal.: 34. 1814). Those who have attributed the name to Roth have done so presumably because they considered B. ammannioides Roxb. to be a nomen nudum. However, as noted by Robinson (in Philipp. J. Sci., C 7: 411–419. 1912), since Roxburgh (l.c. 1814), when he published B. ammannioides, made reference in a footnote to Lechea verticillata Willd., B. ammannioides Roxb. can be accepted as a nomen novum for Lechea verticillata Willd. (Sp. Pl. 1: 495. Jun 1797). Also since Willdenow (l.c. 2: 770. 1799) had validly published the name B. verticillata for another taxon, the epithet verticillata was unavailable in Bergia in 1814 and so B. ammannioides Roxb. (l.c. 1814) is legitimate. Roth (l.c.), when he adopted the name Bergia ammannioides, made no mention of Roxburgh, indeed it would seem that he was quite unaware of Roxburgh's use of the name. Roth indicated that he based his B. ammannioides on a specimen that he had received from Heyne. He also gives Heyne as the source of the name. As this was not the source of Willdenow's Lechea verticillata, it is therefore considered that, under Art. 53.1 of the ICN (Turland & al. in Regnum Veg. 159. 2018), B. ammannioides Roth is a later homonym of B. ammannioides Roxb. It is obvious that authors whether they used B. ammannioides Roth or B. ammannioides Roxb. thought they were applying the same name to the species. For the purpose of determining the traditional usage of the name B. ammannioides Roxb., the only practical solution is to treat the adoption of B. ammannioides Roth by an author as a bibliographic error for B. ammannioides Roxb. The species to which the name Bergia ammannioides has been applied occurs over a wide region extending from Africa through Asia to Australia. Bergia ammannioides is a common weed of rice paddies and waste places in many regions of the world (e.g., Verdcourt, l.c.; Holm & al., Geogr. Atlas World Weeds: 45. 1979; Soerjani & al., Weeds Rice Indonesia: 268–269. 1987). Both Roth (l.c.) and Roxburgh (l.c. 1814; Fl. Ind., ed. 1832: 389. 1832) applied the name Bergia ammannioides to a 5-merous taxon. Later, Wight (in Bot. Misc. 3: 93–95. 1832) published the name B. ammannioides var. triandra for a closely related 3(–4)-merous taxon. Fischer & Meyer (in Linnaea 10: 69–75. 1835) recognised this taxon as a distinct species and published the name B. trimera. In addition to the number of floral parts, the distinctness of the two taxa is supported by the characters of indumentum (glandular hairs in B. ammannioides), shape of sepals and petals, style/stigmas (sessile in B. trimera) and seed ornamentation. Bergia trimera appears to be confined to India, Sri Lanka and Australia, while B. ammannioides has a wider distribution including Africa, the Middle East, India, Asia and Australia. The author has not observed the 3-merous and 5-merous elements mixed in the one population nor mixed gatherings on herbarium sheets to indicate that both elements might occur in the same population. It was found that Bergia ammannioides has been applied by only a few workers in Africa and Asia (e.g., Verdcourt, l.c.; Sohmer, l.c.) in a broad sense, to include both 3(–4)- and 5-merous plants. However, most have applied the name to the 5-merous plants only, e.g., in India (Roxburgh, l.c. 1832), Pakistan (Ghapoor & Ali in Nasir & Ali, Fl. W. Pakistan 19: 1–5. 1972), Middle East (Rechinger, Fl. Lowland Iraq: 433. 1964; Zohary in Zohary & Feinbrun-Dothan, Fl. Palaest. 2: 364–366. 1972), Africa (Oliver, Fl. Trop. Afr. 1: 151–154. 1868; Wild in Exell & Wild, Fl. Zambes. 1: 373–378. 1961; Obermeyer in Codd & al., Fl. S. Africa 22: 28. 1976; Boutique, Fl. Congo, Rwanda & Burundi 7: 1–3. 1967), Taiwan (Huang, Fl. Taiwan, ed. 1, 3: 788–790. 1977), Malesia (Backer, l.c.; Backer & Bakhuizen van den Brink, l.c.) and Australia (Black, Fl. S. Australia, ed. 2, 3: 579–580. 1952 [photolitho repr. 1964]; Cunningham & al., Pl. W. New South Wales: 499. 1981; Verdon, l.c.; Jessop & Toelken, Fl. S. Australia 2: 881–883. 1986; Leach in J. Adelaide Bot. Gard. 11: 75–100. 1989, in Fl. Australia on line, https://profiles.ala.org.au/opus/foa/profile/Bergia 2019; Jacobs in Harden, Fl. New South Wales 1: 492–493. 1990, and Wheeler, Fl. Kimberley Region: 155–158. 1992). All the Australian authors above include the 3(–4)-merous species as distinct from the 5-merous one in their treatments and adopt B. trimera Fisch. & C.A. Mey. (l.c.) for the former. A few workers (e.g., Bentham, Fl. Austral. 1: 178–181. 1863; Thiselton Dyer, l.c.; Trimen, Handb. Fl. Ceylon 1: 92. 1893) have treated the 3(–4)-merous plants as only varietally distinct from the 5-merous plants. These workers have adopted either B. ammannioides var. trimera (Fisch. & C.A. Mey.) Benth. (l.c.) (e.g., Thiselton Dyer, l.c.), or the earlier B. ammannioides var. triandra Wight (l.c.) (e.g., Trimen, l.c.) for the 3(–4)-merous taxon. The only use of the name B. ammannioides in the strict sense for the 3-merous species was in India by Mathew & Britto (in Mathew, Fl. Tamilnadu Carnatic 3: 86–91. 1983) and Mathew (Excurs. Fl. Centr. Tamilnadu: 28. 1991). Since Bergia ammannioides Roxb. was published as a replacement name for Lechea verticillata its type is the type of L. verticillata (Art. 7.4). There appears to be no published account on the typification of L. verticillata. Willdenow (l.c.), when he published the name L. verticillata, cited no specimens but reported the origin of the species as “Habitat in India orientali” and that he had seen dried material. According to Hiepko (Herb. Willdenow: Alphabetical Index, IDC, 1972), Schlechtendal usually wrote the name of the species in the top right-hand corner of the sheet and the name of the botanist from whom Willdenow had received the specimen(s) in the lower right-hand corner. Also when available Willdenow's description labels were attached to the outside of the herbarium folder. The only sheet in the Willdenow Herbarium at Berlin that has been annotated “L. verticillata” by Schlechtendal is sheet number 2396/1 (barcoded as B -W 02396 -01 0). This sheet also bears in the lower right-hand corner Schlechtendal's annotation “Klein Ind. 1794” indicating that the material was collected by D. Klein in India and that Willdenow had received it in 1794. The folder has attached to it a label in Willdenow's hand, which reads in part “Triandria Trigynia | Lechea verticillata floribus | verticillatis, […]”. It would seem reasonable that the dried material referred to by Willdenow in his protologue of L. verticillata is preserved on this sheet. There are two plants attached to this sheet both of which fit the modern concept of Bergia. The plant on the left-hand side is 3-merous and is referable to the species for which Fischer & Meyer (l.c.) published the name B. trimera, while the one on the right-hand side is 5-merous and is referable to the species for which both Roxburgh (l.c. 1814) and Roth (l.c.) adopted B. ammannioides. As I noted on the sheet in B-W (on 24 June 1991), the two plants clearly represent different gatherings and are, therefore, two different specimens (Art. 8.2). Since it can be assumed that both specimens on sheet 2396/1 were available to Willdenow prior to the publication of the name Lechea verticillata, it would seem reasonable to accept both specimens on this sheet as original material (Art 9.4) of the name L. verticillata. In the protologue of L. verticillata, Willdenow stated: “Calyx triphyllus. Corolla tripetala. Stamina tria.” and “Styli tres. Capsula trilocularis.” This information is in full agreement with the specimen on the left-hand side but it is in conflict with the specimen on the right-hand side. The designation of the specimen on the right-hand side as the type of L. verticillata would enable the current usage of Bergia ammannioides to be maintained. However, such a designation would be in danger of being superseded on the grounds that “it is in serious conflict with the protologue, in which case an element that is not in conflict with the protologue is to be chosen” (Art. 9.19), leading to the designation of the left-hand specimen as lectotype. Bergia ammannioides Roxb. was published as an avowed substitute for Lechea verticillata and so, whichever of the two specimens in the Willdenow Herbarium is designated as type, is also the type of B. ammannioides. If this were to be the left-hand specimen the name B. ammannioides would have to be adopted for the 3(–4)-merous species presently known as B. trimera. It would also mean that B. ammannioides var. ammannioides would have to be adopted for the 3(–4)-merous taxon by those who consider the 5- and 3(–4)-merous taxa to be distinct at only the varietal level, and a new varietal name would have to be published for the 5-merous taxon. However, as it has been shown above that Bergia ammannioides in the strict sense has been widely and consistently used, since 1821, for the 5-merous taxon and that its use in this sense persists to the present day, the adoption of B. ammannioides for the 3-merous species would be prevented by Art. 57.1 “unless and until a proposal to deal with it under Art. 14.1 or 56.1 has been submitted and rejected”. We consider that nomenclatural stability would be served best if the name Bergia ammannioides were to continue in use for the 5-merous taxon. We therefore propose that Lechea verticillata Willd. (l.c), the replaced synonym of the name B. ammannioides, be conserved with the specimen on the right-hand side of the sheet B -W 02396 -01 0 in the Willdenow Herbarium. This would ensure that the name B. ammannioides Roxb. (l.c. 1814) continues in use in the strict sense for the 5-merous species by those who regard the 5-merous and 3(–4)-merous taxa to be specifically distinct and in the broad sense by those who refer the 5-merous and 3(–4)-merous plants to the same species. It would also enable B. ammannioides var. ammannioides to continue to be used for the 5-merous taxon by those who consider the 5 and 3(–4) merous taxa to be distinct only at the varietal level. The alternative of simply designating the right-hand specimen as lectotype seems not to be a viable option, given its significant conflict with the protologue. GJL, https://orcid.org/0000-0001-5171-7843 The original manuscript for this proposal was co-authored by the late Gillian Perry of the Western Australian Herbarium. I am greatly indebted to her nomenclatural wisdom. I am also grateful to John McNeill for helpful discussion on this proposal and his meticulous editing.