Flora of North America species comparison

Passiflora incarnata probably has been expanding its range due to its preference for open, disturbed areas, possibly since prior to European settlement (K. J. Gremillion 1989). The species is probably native no farther north than southern Illinois and Ohio, central or southern Virginia, and central West Virginia (C. Frye and B. McAvoy, pers. comm.); it is very cold-hardy, and is introduced sporadically northwards (for example, G. Moore 1989; G. J. Wilder and M. R. McCombs 2002). This species can spread over large areas in well-drained soil, primarily by suckers from deep, far-spreading roots, and has been considered a weed of croplands (W. C. Muenscher 1980). Despite its aggressiveness, it is considered rare in some parts of its range (Indiana, Ohio).

Passiflora incarnata is used for its sedative properties (J. A. Beutler and A. DerMarderosian 2005; A. Chevallier 1996). The species was possibly cultivated by Native Americans, or at least exploited by them for its edible fruit, for over 3,000 years prior to European settlement in North America (K. J. Gremillion 1989). The Cherokee used it for skin infections and earaches, as a liver tonic, and for weaning babies, and the Houma used it as a blood tonic (D. E. Moerman 1986). Fruits of P. incarnata vary in palatability, more flavorful ones suggesting potential value as a fruit crop (C. M. McGuire 1999).

A similar species, Passiflora edulis Sims, has been sparingly naturalized in southern Florida (R. P. Wunderlin and B. F. Hansen 2003), although such material has not been collected there since the 1960s. It is closely related to P. incarnata (V. C. Muschner et al. 2003) and will key to this species in this treatment. Passiflora edulis differs from P. incarnata by its larger stipules, at least 10 mm; leaf margins generally more coarsely serrate; larger, leaflike floral bracts, at least 17 × 8 mm; and a broadly and abruptly expanded androgynophore base (gradually expanded in P. incarnata). Passiflora ‘Incense’, an artificial hybrid between P. incarnata and the South American P. cincinnata Masters, also will key to P. incarnata in this treatment. It differs from the latter by consistently having five-lobed leaves with lobes that are much-narrowed basally, and larger floral bracts, at least 15 × 10 mm.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera 17, species ca. 750 (1 genus, 18 species in the flora).

Passifloraceae have been historically assumed to be closely related to Achariaceae, Caricaceae, Cucurbitaceae, Flacourtiaceae, Malesherbiaceae, and Turneraceae (A. Cronquist 1981); they are currently considered to be most closely related to the latter two families, seated within Malpighiales (D. E. Soltis et al. 2000; M. W. Chase et al. 2002; Angiosperm Phylogeny Group 2003; N. Korotkova et al. 2009). All three families have cyanogenic compounds, flowers with a hypanthium often not bearing the stamens, a floral corona (although uncommon in Turneraceae), tricarpellate ovaries with three elongate styles, parietal placentation, and five stamens (Cronquist; Angiosperm Phylogeny Group). Because of the close relationship of these three families, they have recently been treated as an expanded Passifloraceae (Chase et al.; Angiosperm Phylogeny Group). Passifloraceae are still considered relatively closely related

to members of the now ex-Flacourtiaceae, particularly Salicaceae in the broad sense (Chase et al.), which includes the apparently corona-bearing Abatia Ruiz & Pavón (coronal filaments in Abatia, unlike those in Passifloraceae, are clearly staminal appendages; see A. Bernhard 1999), although the members of Flacourtiaceae that have cyanogenic compounds are possibly more distantly related to Passifloraceae and are now placed in a greatly expanded Achariaceae (Chase et al.). The family description provided above represents Passifloraceae in the narrow sense; Malesherbiaceae and Turneraceae are not included.

Passifloraceae are divided into two tribes: Passifloreae de Candolle, containing genera with tendril-bearing vines and scandent shrubs (or rarely small trees without tendrils), and Paropsieae de Candolle, containing genera without tendrils that are shrubby or arborescent (W. J. J. O. de Wilde 1971). Paropsieae have been assigned to Flacourtiaceae or are seen as transitional between Flacourtiaceae and Passifloraceae (de Wilde). Morphological evidence supports the inclusion of Paropsieae within Passifloraceae (E. S. Ayensu and W. L. Stern 1964), further supported by recent molecular phylogenetic evidence (D. E. Soltis et al. 2000; M. W. Chase et al. 2002). Beyond this, intergeneric relationships are largely unknown within Passifloraceae. The tribes may not be distinct as currently defined and some genera are probably derived from within Passiflora (that is, Hollrungia K. Schumann and Tetrapathaea (de Candolle) Reichenbach; S. E. Krosnick and J. V. Freudenstein 2005).

The floral corona of Passifloraceae is of uncertain origin, considered derived from the perianth (V. Puri 1948) or consisting of staminodes (P. K. Endress 1996). It has an unusual pattern of development, inward from the outer and inner margins of a ringlike primordium; its development is delayed until well after the fertile stamens begin to form; and the arrangement and number of coronal filaments is not consistent with that of the fertile stamens. There is little support for the corona being derived from perianths or staminodes (A. Bernhard 1999).

(Discussion copyrighted by Flora of North America; reprinted with permission.)