Xiphidium caeruleum Aubl., Hist. Pl. Guiane 1: 33, pl. 11. 1775.

Pellegrini, Marco O. O., Hickman, Ellen J., Guttierrez, Jorge E., Smith, Rhian J. & Hopper, Stephen D., 2020, Revisiting the taxonomy of the Neotropical Haemodoraceae (Commelinales), PhytoKeys 169, pp. 1-59 : 1

5.1. Xiphidium caeruleum Aubl., Hist. Pl. Guiane 1: 33, pl. 11. 1775. Figs 22 , 23 , 24

Xiphidium floribundum var. caeruleum (Aubl.) Hook., Bot. Mag. 84: t. 5055. 1858. Lectotype (designated by Maas and Maas-van de Kamer 1993). [Illustration] Original parchment plate of Histoire des Plantes de la Guiane Françoise and later published in Aublet, Hist. Pl. Guiane 1: 33, pl. 11. 1775.

Xiphidium floribundum Sw., Prodr.: 17. 1788.

Xiphidium albidum Lam., in Lamarck & Poiret Tabl. Encycl. 1: 131. 1791, nom. superfl.

Xiphidium album Willd., Sp. Pl. Editio quarta 1(1): 248. 1798.

Xiphidium floribundum var. albiflorum Hook., Bot. Mag. 84: t. 5055. 1858, nom. superfl. (≡ X. floribundum Sw. var. floribundum ).

Xiphidium caeruleum var. albidum (Lam.) Backer, Handb. Fl. Java 3: 80. 1924.

Xiphidium loeflingii Mutis, Diario 2: 51. 1958, nom. nud.

Eccremis scabra Kuntze, Revis. Gen. Pl. 3(3): 316. 1898. Holotype. destroyed (B†). Lectotype (designated here). BOLIVIA. Cochabamba: Chapare, Río Juntas, fr., 13-21 Apr 1892, C.E.O. Kuntze 461 (NY barcode 00841967!), Syn. nov.

Xiphidium giganteum Lindl., Edwards’s Bot. Reg. 32: page prior to t. 67. 1846. Type. (K?, not found).

Xiphidium fockeanum Miq., Linnaea 17: 63. 1843. Lectotype (designated by Maas and Maas-van de Kamer 1993). SURINAM. prope Paramaribo, fl., April 1654, H.C. Focke 293 (U barcode U0002449!; isolectotype: P barcodes P00753474!, P02188828!).

Xiphidium rubrum D. Don, Edinburgh New Philos. J. 13: 235. 1832. Lectotype (designated here). PERU. s.loc., fl., s.dat., J.A. Pavón 358 (BM barcode BM000923989!; isolectotype: MA barcode MA810534!).

Ornithogalum rubrum Ruiz & Pavón ex D.Don, Edinburgh New Philos. J. 13: 235. 1832, nom. not validly published, pro. syn.

Durandia macrophylla Boeckeler, Allg. Bot. Z. Syst. 2: 173. 1896. Holotype. COSTA RICA. s.loc., fl., Nov 1893, A. Tonduz 8402 (B barcode BR0000006885779!), Syn. nov.

Tonduzia macrophylla Boeckeler ex Tonduz, Bull. Herb. Boissier 3: 464. 1895, nom. nud.

Nomenclatural notes.

The taxonomic circumscription of X. caeruleum is greatly impaired by the lack of knowledge of the current whereabouts of the type material of several of its associated synonyms. Types for the names X. caeruleum and X. fockeanum were successfully located and designated by Maas and Maas-van de Kamer (1993), while types for the names X. rubrum , Eccremis scabra , and Durandia macrophylla were located by us and had lectotypes designated when necessary. Nonetheless, we have been unable to locate a type specimen, or illustration for X. giganteum , which prevents us from knowing if this name matches any of the X. caeruleum morphs recognised by us.

Maas and Maas-van de Kamer (1993) erroneously designated plate 66 from Lindley (1846) as the lectotype of X. giganteum . The indicated plate actually depicts Swainsona greyana Lindl. ( Fabaceae ) and obviously cannot be the type for X. giganteum . In fact, the original publication ( Lindley 1846) provides no illustration for X. giganteum . Lindley (1846) mentions that a live specimen was brought from Caraccas and flowered in Syon [Park], London, UK. After searching for specimens that matched these data at K herbarium, we were unable to locate any. We have also searched for a possible unpublished illustration that might serve as the type for X. giganteum , but were also unsuccessful. Thus, we are currently unable to designate a lectotype for X. giganteum , since this name completely lacks any original material (Art. 9.4., Turland et al. 2018). Since the original description is not enough to undoubtedly apply this name, we also feel it is premature to designate a neotype until natural populations from Caraccas have been studied. Finally, we also choose to tentatively retain it under the synonymy of X. caeruleum until further information becomes available.

As explained by Dorr and Wiersema (2010), Ixia xiphidium Loefl. represents a misinterpretation by Maas and Maas-van de Kamer (1993) of Loefling’s (1758) publication. The author never intended to publish a new species but published a new genus, rejecting the application of Ixia L. for American plants. Thus, Ixia xiphidium Loefl. was never published and should not be included in databases.

When describing X. rubrum , Don (1832) mentions his new species is based on a Ruiz & Pavón collection, but without indicating a collection number or herbarium information. We came across a specimen matching the protologue with a label in Pavón’s handwriting during a visit to BM, saying, " Ornithogalum rubrum sp. n., Fl. Per. ". This specimen is here selected as the lectotype.

Kuntze (1898) described Eccremis scabra , based on a collection from Río Juntas, Bolivia. The author mentions a specimen at B, but we were unable to locate it, and it might have been lost during WWII. Luckily, we were able to locate a duplicate at NY, which is designated here as the lectotype.

Distribution and habitat.

Xiphidium caeruleum is widely distributed in the Neotropics, ranging from Mexico, reaching the Antilles, to northern South America (Fig. 25 ). It can be found growing in permanently or seasonally-wet environments, more rarely in dry and rocky environments.

Phenology.

It was found in bloom and fruit throughout the year.

Conservation status.

As currently circumscribed, Xiphidium caeruleum is widely distributed, with equally wide EOO (14,922,959 km2) and AOO (ca. 3,056 km2). Thus, following IUCN’s (2001) recommendations, X. caeruleum should be considered as Least Concern (LC).

Comments.

Xiphidium caeruleum is a widely-distributed species and still a variable taxon even in our present circumscription. Despite our best efforts, we have been unable to correlate any of the observed morphological variability to any of the previously proposed names in Xiphidium . After careful study of protologues, we concluded that X. loeflingii Mutis, X. caeruleum var. albidum (Lam.) Backer, X. floribundum var. albiflorum Hook., X. album Willd., X. albidum Lam.. and X. floribundum Sw. actually represent homotypic synonyms and are unambiguously conspecific with the type of X. caeruleum . Alternatively, Durandia macrophylla Boeckeler, Eccremis scabra Kuntze, X. fockeanum Miq. and X. rubrum D.Don represent heterotypic synonyms. Xiphidium giganteum Lindl. is tentatively kept here as a heterotypic synonym of X. caeruleum until further information on its type specimen is acquired.

All diagnostic characters provided by the original authors in their respective protologues can be easily observed in the typical morph of X. caeruleum . Some peculiar specimens of X. caeruleum are recorded for French Guiana (in which the specimens seem to present peculiarly large, red, crustose, and trigonous fruits), Costa Rica (where some specimens possess flowers with three inconspicuous green nectar guides at the base of the upper tepals) and Mexico (where specimens present inner tepals much longer than the outer tepals and perianth generally with apricot to pinkish hue). Furthermore, it is also known for berries of X. caeruleum to range from yellowish-orange to orange with reddish-orange spots, to completely red. We were unable to find any obvious correlation between the different colours of berries, geographical distribution, and the observed genetic diversity. Nonetheless, due to limited access to such morphs and also due to herbarium specimens in Xiphidium being generally poorly preserved, we consider it premature to recognise or propose any taxonomic status for these morphs. Thus, we propose that studies focusing on population genetics and reproductive biology, associated with a morphometric study and intense field studies, are necessary to properly deal with the issue.

Figures

Figure 22. Xiphidium caeruleum Aubl. A specimen growing in a flooded forest B habit C inflorescence D cincinnus E, F flower: E flower with subequal, narrow, and pale apricot perianth lobes F flower with equal, broad, and white perianth lobes G flower with perianth removed showing androecium and gynoecium with ovary pubescent long the septal ridges H cincinnus with immature berries I mature berries. A, F by R. Aguilar, B by H. Medeiros, C-D, G, I by M. O. O. Pellegrini, E by A. Yakovlev, and H by R. Cumming.

Figure 23. Xiphidium caeruleum Aubl. Line drawing of the inflorescence. Illustration by E. J. Hickman. Scale bar: 1 cm.

Figure 24. Xiphidium caeruleum Aubl. A roots in cross-section B-D rhizome: B naked rhizome C longitudinal section D lateral branch E cincinnus F flower bud G hairs H, I flower: H frontal view I side view J flower with the perianth removed, showing the androecium and gynoecium K lateral stamen (frontal and dorsal view) L stigma M-P fruit: M immature berry N berry in cross-section O berry in longitudinal section P indehiscent and old berry Q-T seed: Q dorsal view R lateral view S ventral view T longitudinal section. Illustration by E. J. Hickman. Scale bars: 0.8 mm (A); 1.5 cm (B-D); 0.75 mm (E); 2 mm (F, H, I, M-P); 0.4 mm (G); 1.75 mm (J); 1 mm (K); 0.5 mm (L, Q-T).

Figure 25. Distribution of Xiphidium caeruleum Aubl. Beige - Temperate Coniferous Forests and Boreal Forests; Yellow - Temperate Grasslands, Savannahs and Shrublands; Pink - Temperate Broadleaf and Mixed Forests; Light Green - Subtropical Coniferous Forests; Red - Deserts, Xeric Shrublands and Tropical Coniferous Forests; Orange - Tropical / Subtropical Grasslands, Savannahs and Shrublands; Maroon - Dry Broadleaf Forests; Green - Moist Broadleaf Forests; Lilac - Montane Grasslands and Shrublands.