By P.M. Jørgensen and J.M. MacDougal

The first literature report of a plant referable to Passiflora is found in Pedro de Cieza de León’s (1553) description of Cali in Colombia in which he mentions Granadilla as a fruit “tree” in the orchards surrounding the city. It is likely that he observed Passiflora ligularis, still recognized as Granadilla and widely cultivated from Mexico to Bolivia. Today, Cieza de León is commemorated by the supersection Cieca in subgenus Decaloba .

In the 16th century more information about these fascinating plants can be found in the works of Nicolás Monardes (1569, 1574). He was born in Sevilla in 1493 and practiced medicine there until his death in 1588, but never visited the Americas. He was, through second hand knowledge and materials brought to him, the first to publish detailed observations of Passiflora, and also the first to describe tobacco and coca. He described the fruit and seeds of Passiflora in detail, and tells us that the plant climbs everywhere it can. He further indicates that the flowers were carefully made to represent the Passion of Christ. This indication initiated numerous accounts of the symbolism and mysticism of the Flos de Passionis .

Several pre-Linnean botanist such as Hernández, Pluckenet, Plumier, and Tournefort described species of Passiflora, but Johan Gustav Hallman’s thesis under the direction of Linnaeus (1745) was the first monograph of the genus and dealt with 22 species. His work had a surprisingly modern outline with chapters on the history, higher classification, description of the genus and species, dubious species, relationships, distribution, economic uses, superstition, and poetry.

From the taxonomic starting point in 1753, Linnaeus named 24 species using a binomial naming system. The number of new species that were discovered and described increased to 35 (Lamarck 1789), and our understanding was much improved by Cavanille’s (1790) monograph which included 43 species and 32 illustrations. Jussieu (1805a–b) published 15 new species and argued in favor of the establishment of the family. De Candolle (1828) listed 145 species from the Americas and Roemer (1846) included 225 species. The first infrageneric categories were established by De Candolle (1822, 1828) one of which were section Decaloba as one of seven subdivision of the genus.

The mayor monographic works, which continue to be of great importance in the genus, were carried out by Maxwell Tyndell Masters, Hermann August Theodor Harms, and Ellsworth Paine Killip. Masters published more than 69 papers on Passifloraceae. He was an editor of Gardener’s Chronicle and published numerous new species there. His most important works were an outline of the family (1871) and his contribution to Martius’ monumental Flora Brasiliensis (1872).

Harms followed Masters and wrote 36 publications on Passifloraceae. The two most important publications were his thesis (1893a), an analysis of anatomical characters and their importance for classification of the family, and his contribution to Engler and Prantl’s Natürlichen Pflanzenfamilien (1893b, 1925). His contributions, along with Masters, were very influential in elaborating a classification system within this large and morphological diverse genus.

The work of Killip (1938) established a system with 22 subgenera largely based on groupings recognized earlier by either Masters or Harms. Killip included 355 species of which 47 were described as new. For almost 70 years this has been the main resource in Passiflora taxonomy. Killip did however, not include the approximately 20 Old Word species in his monograph. Those species were monographed by Willem J.J.O. de Wilde (1972). Finally, Feuillet and MacDougal (2003) introduced a simplified infrageneric classification which recognized only four subgenera, including subgenus Decaloba.

Since the publication of Killip’s monograph, all publications on the genus have either been framed as a flora of an area (Holm-Nielsen et al. 1988, Escobar 1988) or as a monograph of a smaller monophyletic group (MacDougal 1994), or though numerous publications of new species (e.g. MacDougal 1992, Feuillet 1994, Jørgensen & MacDougal 1997). A new complete monograph of the genus is long overdue considering that the number of new taxa (species and infraspecific taxa) published since 1938 is 271 and the number of accepted species is now considered to be around 525. We have a situation where approximately 175 species cannot be identified using a synoptic key, but only through the knowledge and experience accumulated by specialists in the group.

The main sources for this compilation were Killip (1938) and Kugler & King (2004).