Sunday, June 25, 2017

[Botany • 2017] Delimitation of the Series Laurifoliae in the Genus Passiflora (Passifloraceae)


Flowers of some Passiflora series Laurifoliae.


Abstract

Within the huge diversity of genus Passiflora, series Laurifoliae constitutes a strikingly uniform group, widely distributed in neotropical rain forests, at low to moderate elevations. Given its morphological and ecological unity, Killip mentionned it as an «exceedingly difficult» group. The lack of clear morphological criteria has not helped in delimiting it, and the confusion has grown with the addition of new species and criteria. As a preliminary step in the study of diversity within series Laurifoliae, we re-examine its morphological delimitation, assessing how its current 29 species (including the highly similar P. pachyantha and P. killipiana) conform to 20 criteria from different authors. Three criteria (indumentum on vegetative parts, stipule glands, membranous limen) appear to be irrelevant, because they are either too variable or rarely recorded in the species descriptions. Using the 17 remaining ones, 24 typical species show very limited variations, five of them differing by only one criterion. Among them, we retain terete to angular stem, setaceous or linear stipules soon deciduous, petiolar glands in one pair, leaves oblong, neither peltate nor lobate, three glandular bract over 1 cm long and free, flowers pendent, with two campanulate outer series of filaments (most other series much reduced or aborted). Five species, P. guazumaefolia, P. kikiana, P. odontophylla, P. ischnoclada, and P. maliformis, differ by three to nine traits, not found in the typical representatives of the series, so they can be excluded from it. Passiflora kikiana should be classified into series Kermesinae. For the four other ones, a satisfactory solution implies a more global study, involving other series.

Keywords: Violales, Malpighiales, Passifloraceae, Passiflora, Eudicots


Figure 1. Flowers of the series Laurifoliae.
A: Passiflora acuminata (photo: J. B. Fernandes da Silva); B: P. ambigua (photo: R. Aguilar); C: P. venusta (photo: D. Scherberich); D: P. cerasina (photo: M. Vecchia); E: P. crenata (photo: M. Rome); F: P. fissurosa (photo: M. de Souza); G: P. laurifolia (photo: F. Booms); H: P. nigradenia (photo: D. Scherberich); I: P. nitida (photo: M. Rome); J: P. popenovii (photo: G. Coppens d’Eeckenbrugge) ; K: P. rufostipulata (photo: C. Houel); L: P. gabrielliana (photo: M. Rome) : M: P. ischnoclada (photo: C. Houel); N: P. kikiana in Cervi (2010); O: P. guazumaefolia (photo: J. Ocampo); P: P. odontophylla (flower of the type specimen). 

Conclusion: 
Several diagnostic characters used by Killip and Cervi (indumenta on vegetative organs, glandular stipules, bracts rounded at apex (with reservation), limen presence and shape), appear to be variable in the series, so they can still be used to differentiate species of the series, not to delimit the series. As a variable quantitative trait, leaf width is also questionable. The criteria “campanulate calyx tube” and “tubular or filamented operculum” are characters shared by all species of supersection Laurifolia. We can also exclude them from the definition of series Laurifoliae. These modifications allow restoring a homogeneous series Laurifoliae, which could be defined as follows:

 Series Laurifoliae — Plants glabrous to pubescent. Stems terete to angular, wingless, sometimes corky on old parts. Stipules linear to setaceous, early deciduous. Petiole with two discoid to oblong sessile glands (except in populations of P. popenovii). Leaves unlobate, oblong-lanceolate, entire to glandular-serrulate, not peltate. Bracts three, in involucre, free at base, more than 1 cm long and glandular. Flowers pendent. Outer series of filaments two, campanulate (most other series much reduced or aborted).

 Currently, series Laurifoliae includes 24 species corresponding to the above criteria: P. acuminata, P. ambigua, P. capparidifolia, P. cerasina, P. chaparensis, P. crenata, P. fernandezii, P. fissurosa, P. gabrielliana, P. gleasonii, P. kapiriensis, P. killipiana, P. laurifolia, P. metae (when type effectively deposited), P. nigradenia, P. nitida, P. pachyantha, P. pergrandis, P. phellos, P. popenovii, P. riparia, P. rufostipulata, P. tolimana, and P. venusta.


Maxime Rome and Geo Coppens d'Eeckenbrugge. 2017. Delimitation of the Series Laurifoliae in the Genus Passiflora (Passifloraceae). Phytotaxa. 309(3); 245–252.  DOI: 10.11646/phytotaxa.309.3.5


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