A new lectotype for Passiflora laurifolia L.

Abstract From the "Description des plantes d'Amérique" by Plumier, in 1693, to the "Species Plantarum" by Linnaeus in 1753, several dubious synonymies of Passiflora laurifolia L. were proposed, generating a persisting confusion. A revision of the process, which led to the Linnaean description of this species, shows that the type finally chosen by Cusset does not match the original description. A new lectotype for the species and a more complete description are proposed from field observations, herbarium and bibliographic data.

Supersection Laurifolia (Cervi, 1997) Feuillet and MacDougal (2003) is part of subgenus Passiflora. It includes series Laurifoliae Killip (1938) ex Cervi (1997), which forms a morphologically very homogenous group, with a very difficult taxonomy. It is composed of 24 species including glabrous to pubescent plants, with stems that are terete to angular and sometimes corky on old parts; leaves that are entire, oblong-lanceolate, not peltate, with entire to glandular-serrulate margins, biglandular petioles; and stipules that are setaceous or linear, early deciduous. Their three bracts, free at the base, with entire or serrulate-glandular margins, are more than 1 cm long. Their flowers are pendent, usually large and showy, often fragrant with a short hypanthium and two campanulate series of long external filaments and a variable number of series of reduced internal filaments (Rome and Coppens d'Eeckenbrugge 2017). They are valued for their soft and sweet pulp and some species are grown commercially, including P. laurifolia.
Passiflora laurifolia Linnaeus (1753) was one of the earliest passion flowers to be described and, logically, the first one in the series Laurifoliae. It was first mentioned and illustrated in the "Description des plantes d'Amérique" by Plumier (1693), amongst 12 passion flower species from the Caribbean, under the polynomial Clematis indica, fructu citriformis, foliis oblongis (climbing plant from the Indies, with lemon-shaped fruits and oblong leaves). Linnaeus (1753) recognised Plumier's polynomial, as well as several other polynomials and illustrations under his P. laurifolia; however, as stated by Killip (1938), this species is not represented by a true type in the Linnaean Herbarium and several Linnaean specimens correspond to the very similar P. nitida Kunth (1817), another member of the series Laurifoliae. Thus, when Cusset (1967) finally typified P. laurifolia, he chose, amongst Linnaean materials, an illustration on plate 21 by Merian (1705) representing in fact a specimen of P. nitida from Suriname.
Here, the pre-Linnaean and Linnaean treatments of P. laurifolia are revised to support the choice of Plumier's illustration as a new lectotype for this species. Furthermore, the authors compare specimens from the Antilles and South-America to ascertain that they are conspecific and correspond to the successive descriptions of P. laurifolia, discarding any geographical reason for the ancient confusion. A range of materials of P. nitida is also examined. From these observations, a complete description for P. laurifolia is presented.

Materials and methods
Three specimens from the herbarium of the London Linnaean Society (LINN) were observed: Linnaeus (P. laurifolia), not numbered, of unknown origin, number 1070.2 in the herbarium of the London Linnaean Society; Linnaeus 74 (P. nitida), from Suriname; and Linnaeus 152, (Passiflora sp.), of unknown origin.
Other materials of P. laurifolia examined include 28 herbarium specimens from the Antilles and South America, as well as ten living specimens of P. laurifolia with flowers and fruits in Martinique and Guadeloupe. Other materials of P. nitida examined include 50 herbarium specimens from South America and living plants with flowers and fruits from eight populations in French Guiana. Examined materials are presented in more details in Appendix 1 and Appendix 2.

Pre-Linnaean treatment
The authors transcribe here the long and precise description of P. laurifolia in French by Plumier (1693) giving the colour and size of each part of the plant. The plant is woody with only one leaf or fragrant flower at each node. The leaves are ovate-elongated, slightly pointed at apex and indented at base, with two glands at the petiole apex. The flowers are enclosed in three green membranaceous bracts ["dans trois feuilles vertes membraneuses"]. The perianth is white, densely dotted with brown red inside. The two outer series of filaments are not equal, the innermost being about 3.75 cm long and the outermost over 1.25 cm long. They are purple on the distal half and striped with red and purple on their proximal half. Inside the flower, there are two other, very short, slender and whitish series of filaments. The androgynophore is yellowish, marbled with red, with three red styles, three yellow stigmas, a yellow ovary and five stamens with whitish anthers. The fruit is the size of a chicken egg, with three longitudinal ribs, turning orange with many tiny dots at maturity. Plumier describes its pericarp as thin, leathery, ["de l'épaisseur et la consistance d'un gros cuir molasse indiquant que l'enveloppe du fruit n'est pas très épaisse"] and pubescent ["écorce cotonnée par dehors"]. The whitish pulp is mucilaginous and sweet and contains black heart-shaped seeds. The species is cultivated in home gardens and the fruits are ripe from April to May. Plumier's description of P. laurifolia was well illustrated by the drawing presented at Figure 1.
In addition, Plumier (1693) pointed out that the fruit is very similar to those of the "murucuia guaçu" (meaning large passion fruit) of Georg Marcgrave in Ray (1686) and the "murucuia guaçu" of Piso (1648), raising the possibility that they could belong to the same species. However, these two species do not have simple leaves and they cannot even match any species description within series Laurifoliae.
Plukenet (1696) considered Plumier's 'Clematis indica, fructu citriformis, foliis oblongis' a synonym of 'Passiflora arborea Laurinis foliis' represented in table 211 in the book of Plukenet (1692). Indeed, the latter includes a drawing of a passion flower with oblong leaves and two glands at the petiole apex; however there is no textual description of the species and the absence of flowers in the drawing allows no further identification of the species. Additionally, Plukenet (1696) considered two other synonyms: Marcgrave's 'Murucuja 4.s. Pyriformis altera' and an illustrated description of 'Quauh Chichic Patli' by Hernández de Toledo (1651). However, while the synonymy of the former cannot be verified because it gives no indication of the position of petiolar glands, the drawing of the latter shows a plant with opposite leaves, which cannot belong to the genus Passiflora.
Linnaeus (1749) named Passiflora laurifolia as 'Passiflora foliis indivisis integerrimis, involucris dentatis' (Passiflora with undivided leaves and dentate involucres). Amongst synonyms, he quoted the above-mentioned polynomials of Plumier (1693), Plukenet (1692) and van Royen (1740), as well as 'Granadilla fructu citriformi, foliis oblongis' of Tournefort (1700) and an illustration by Merian (1705, pl. 21), where plants are drawn with their pollinator and predator insects. In the legend, Merian (1705) named the plant under the vernacular name 'marquiaas', which is related to the generic vernacular terms murucuia and maracuyá (cf. Cuvier, 1823), used for all passion fruits across South America. On the drawing by Merian (1705), presented in Figure 2, several diagnostic traits are inconsistent with the description of Plumier (1693): flowers with white perianth (instead of flowers densely dotted with brown red inside) and equal (instead of unequal) outer series of blue corona filaments. The ovoid fruit is uniform yellow or green when unripe (instead of dotted with darker ribs), with a thick mesocarp (instead of a thin one).
Linnaeus (1749) specified that P. laurifolia has glabrous and undulate to flat leaves and that bracts are of the same length as the flowers ["involucrum magnitudine floris"], which was a new observation in relation to Plumier's description.

Linnaean treatment
In Species Plantarum, Linnaeus (1753) maintained his description of P. laurifolia from Amoenitates academicae, with the same synonyms but he did not designate a type of this species. He considered the species as only native to Suriname although he based his species' description on that of Plumier from Caribbean specimens. Moreover, the white perianth, the two equal outer series of filaments and the uniformly green immature fruit with a thick pericarp, show that Merian's 'marquiaas' belongs to P. nitida. Killip (1938) specified that P. laurifolia is not represented by a true type in the Linnaean Herbarium even if the latter includes three specimens identified as belonging to this complex group. Only one of them corresponds unambiguously to P. laurifolia; this is Linnaeus nn (no collection number; number 1070.2 in the herbarium of the London Linnaean Society), determined as P. pallida by Linnaeus, with a note from the hand of J.E. Smith: "laurifolia Jacq. non Linn.". Thus, Smith indicated that the herbarium specimen does not match the description of P. laurifolia by Linnaeus but corresponds to that of Jacquin (1776) in Hortus Vindobonensis where this author specifies that P. laurifolia has two series of filaments, the outer series being shorter. Below the first annotation, "pallida" can be read, hand-written by Linnaeus and next to that name, another annotation from Smith: "non Plumeri icon"). Here, Smith referred to an illustration of Plumier, cited in Linnaeus' description of Passiflora pallida Linnaeus (1753), a species of subgenus Decaloba. This suggests that Linnaeus was not comfortable with this group of plants.
The specimen Linnaeus 152, collected in Suriname, was determined by Linnaeus as "Passiflora dubia" (doubtful Passiflora) in Plantae Surinamensis (1775). In this book, he gave a brief description of the plant that does not allow the determination of the species in the absence of bracts. The specimen Linnaeus 74, from Suriname, also noted as "Passiflora dubia" in Linnaeus' Plantae Surinamenses, is in fact P. nitida (the fourth inner series of filaments close to the nectary chamber of the flower is easily observable on the specimen), the species described by Kunth in 1817.

Post-linnean treatment
In his American species of Passifloraceae, Killip (1938) simply followed Linnaeus, maintaining the contradiction between the description of P. laurifolia taken from Plumier and Merian's illustration representing P. nitida. Later, Cusset (1967) mentioned P. laurifolia in Flore du Cambodge du Laos et du Vietnam, considering Merian's drawing as the type of this species.

Analysis of herbarium and living specimens
The authors' literature review and observations confirm that P. laurifolia is present in all of the Caribbean islands; in fact, it is the only species of series Laurifoliae in the Antilles. Regarding its presence on the South American continent, the examined herbarium specimens document its presence in Suriname, Guyana, Venezuela and Brazil. A detailed analysis of the morphology of P. laurifolia from the Caribbean and South America shows that the internal structure of the flower is identical in both regions (Figure 3).
A comparison of the successive descriptions of P. laurifolia shows that the original one, provided by Plumier (1693) is the most complete and comprehensive and constitutes the common reference linking all subsequent descriptions of the species. Even now, it allows the discrimination of P. laurifolia amongst the 24 species composing series Laurifoliae (Rome and Coppens d'Eeckenbrugge 2017). The species described by Piso (1648), Hernández de Toledo (1651) and Marcgrave in Ray (1686) are to be invalidated and the corresponding polynomials cannot be considered as earlier synonyms. The descriptions of van Royen (1740) and Plukenet (1696) are too imprecise, their unique interest being that they refer to that of Plumier (1693). Linnaeus' descriptions (1749, 1753) of P. laurifolia were based on the morphology of two different species, the one described by Plumier (1693) and an iconography of a plant that turned out to be Passiflora nitida. This confusion has persisted until now, with the treatments of Killip (1938) and Cusset (1967). According to the article 9.19(b) of the Interna- tional Code of Nomenclature (McNeill et al. 2012), the choice of the lectotype may also be superseded if one can show that it is in serious conflict with the protologue and another element is available that is not in conflict with the protologue. Thus, the iconotype of Merian (1705) is replaced here by that of Plumier (1693). A complete description of P. laurifolia is also presented here, based on that of Plumier and examination of materials from the Antilles and the Guianas. Description. Liana strong. Stem terete, glabrous and green; internodes 3.5-14 cm long. Tendrils cone-shaped, glabrous. Stipules linear, falcate, green yellowish to green brown, eglandular to glandular (0-2 glands), glabrous, 5.5-13.2 × 0.4-1 mm (including an arista, 0-1.8 mm long), deciduous. Petiole 1.1-2.9 cm long, green to dark green, slightly caniculate adaxially, glabrous, with two oval sessile glands situated at petiole apex. Leaves simple, 7.3-14.2 × 4.4-7.5 cm, glabrous throughout, green to dark green, adaxial surface lustrous, rounded to cordate at base, acute (angle within 45 to 90°) at apex, slightly acuminate and mucronate; leaf margin entire or glandular (7-25 marginal nectaries). Peduncles 1.5-7.4 cm long, terete, green, glabrous to slightly pubescent, strong (diameter about 1.3-2.4 mm); pedicel 6.7-15 mm long. Bracts permanent (until fruit maturity), slightly pubescent on both sides, green, concave, 2.8-5.5 cm long, 2.2-4.9 cm wide (same length as flowers), with 4-11 marginal nectariferous sessile glands in distal half. Flowers axillary, pendulous, 22-33 mm long (from the nectary chamber to the ovary apex). Hypanthium slightly pubescent, green outside and white inside, 2.59-5.94 mm, with a diameter of 10.35-16.64 mm at the base of sepals. Nectary chamber slightly pubescent, green outside and white inside, 3.1-5.9 mm long, with a diameter of 8.8-17.9 mm. Sepals glabrous, oblate, 2.9-5.1 cm long, 1-1.7 cm wide, adaxial surface white with a sparse to very dense red punctuation, abaxial surface green with red-brown dots, slightly keel-shaped in distal half with a short awn (1-2 mm long). Petals glabrous, oblate, 2.8-4.9 cm long, 0.7-1.2cm wide, white with a sparse to very dense red punctuation. Corona filaments in 5-7 series, banded white and red to dark purple (purple on the distal half and striped with red to purple on their proximal half); two major series, slightly curved, the outer series 12-30 mm long, the second series 24-43 mm long; others series about 1 mm long. Ovary pubescent, yellow to green, 7-11 mm long; styles, whitish with red purple dots, 8-13 mm long, stigmas light yellow to green. Stamens 7-11 mm long. Androgynophore glabrous, white greenish with red dots, 10-16 mm long with an enlarged base about 10 mm wide. Operculum membranaceous, 0.5-1.1 mm long, recurved, shortly fimbriated at margin. Fruit ovoid, pubescent, 4.7-8.4 cm long, 3.8-6.3 cm in diameter, round to triangular transversal section, epicarp about 0.5-0.9 cm thick; immature fruits green with white dots and with six longitudinal ribs (three of them conspicuous); mature fruits yellowish orange with many tiny light orange dots. Pulp transluscent and sweet. Seeds heart-shaped, black.

Conclusion
The original description of P. laurifolia by Plumier (1693) is the common reference linking all subsequent descriptions of the species. Linnaeus' descriptions (1749Linnaeus' descriptions ( , 1753 involved two iconographies: the one from Plumier (1693) and one from Merian (1705) representing the closely related Passiflora nitida, described by Kunth (1817). The latter was mistakenly chosen by Cusset as the lectotype of P. laurifolia. To restore consistency, the iconotype of Merian has been replaced by that of Plumier (1693) and a more complete description of P. laurifolia has been presented from field observations, herbarium and bibliographic data.