Passifloraceae

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Passifloraceae

Description

Mostly climbing herbs or lianas with axillary tendrils, rarely erect herbs, shrubs or small trees, glabrous or hairy, in Mal. not spiny. Leaves (mostly) spirally arranged, simple or compound, pinni-nerved or palminerved, entire or lobed; Stipules present. Inflorescences essentially axillary, cymose, sessile or peduncled, 1-many-flowered, ending in (a) tendril(s) or not. Flowers often stiped, articulate to the pedicel, actinomorphic, bisexual or functionally unisexual (either with staminodes or a vestigial ovary, and then plants mostly dioecious) or polygamous. Sepals (4-)5(-6), imbricate. Petals (4-)5(-6), mostly imbricate. Stamens 4-10, inserted mostly at the base of the hypanthium, or on an androgynophore (mostly hypogynous), (mostly) opposite the sepals; Ovary superior, subsessile or on a gynophore or androgynophore, 1-celled, 3(-5)-carpellate; Fruit a loculicidally 3(-5)-valved capsule, or berry-like. Seeds mostly numerous, mostly compressed, often beaked, enveloped by a (membranous or juicy) aril;

Distribution

Africa: present America: present Asia: present Asia-Tropical: Australasia: present, Queensland (Queenslandpresent) Madagascar: present NE. & E. Australia: present New Zealand: present S. & SE. Asia: present SE. Asia: present W. Pacific islands: present
About 10 genera and 500 spp., almost entirely confined to the tropics: in America c. 350 spp. (mainly Passiflora, a few species in Dilkea, Mitostemma, Tetrastylis), in Africa (incl. Madagascar) c. 110 spp. (mainly Adenia c. 80 spp., Tryphostemma c. 20 spp., Deidamia, incl. Efulensia, c. 6 spp., Crossostemma, incl. Schlechterina, 2 spp.), in Asia and Australia c. 40 spp. (Passiflora c. 20 spp., Adenia 14 spp., Hollrungia 1 sp., Tetrapathaea 1 sp. in New Zealand).
The two largest genera are each distributed in two continents, viz Passiflora in America and Australasia (S. & SE. Asia, Malesia, NE. & E. Australia, W. Pacific islands), and Adenia in Africa, Madagascar, SE. Asia, and Queensland.
In addition the tribe Pariopsieae is now arbitrarily reckoned to the Passifloraceae and excluded from the Flacourtiaceae. They are all woody, erect plants and occur in the palaeotropics, only one species being represented in Malesia. See and . The characters by which this tribe differs from Passifloraceae in the strict sense are here not incorporated in the family circumscription. See further below under Taxonomy.

Pollination

Most genera are monoecious with bisexual flowers, Passiflora having a marked protandry; Adenia is monoecious or dioecious, or polygamous. Functionally unisexual flowers occur in Adenia, Hollrungia, and in the New Zealandian Tetrapathaea.
Pollination by bumble-bees and kolibris is known from American Passifloras; for a number of narrow-flowered species of Adenia (Mal. spp.!) pollination by (small) insects is likely. Some African Adenias have fragrant flowers.

Morphology

The axillary tendrils in sterile shoots replace the axillary inflorescences; inflorescences are essentially cymose and the first flower or first 3 flowers of the lowest triad may be replaced by (a) tendril(s). Sometimes the cyme has become monochasial or is deformed by partial concaulescence, or the cymes reduced to 1-3 flowers are contracted into raceme- or panicle-like inflorescences (Passiflora race-mosa). Ramification of the plant takes place through the serial bud.
Studies dealing with the inflorescences and tendrils of Passifloraceae have been made by HARMS (), CUSSET (), and myself ().
With hypanthium in the flower descriptions is meant the usually cup-shaped basal part, which bears on its margin the tepals (mostly free; sepals in Adenia are often partially united into a calyx tube) and the corona (mostly filamentous). Lower down in the hypanthium various types of a disk may be found, mostly annular, in Adenia mostly consisting of 5 scale-like or strap-shaped appendages.
The leaves mostly bear (often large) nectarial glands on petiole and blade.
Seedlings of extra-Malesian species (Passiflora, Adenia) are depicted by LUBBOCK () and DE WILDE ().

Anatomy

See .

Taxonomy

Related to Flacourtiaceae to which the tribe Paropsieae (shrubs or trees) forms a transitional group. Recent anatomical evidence () and palynological studies (; ; PACQUÉ, ined.) point to a closer relationship of Paropsieae with Passifloraceae than with Flacourtiaceae.

Uses

VariousPassifloras are ornamental or have edible fruit. Adenias are sometimes used as fish poison. Because of the showy flowers or edible fruits many species are cultivated in the tropics and subtropics and frequently run wild. Most species are nitrophilous or ruderal and are found in secondary vegetation. Many species are easily propagated either by seeds or cuttings. See .

Phytochemo

Many members of the family are toxic. The toxic constituents are still incompletely known. Most species of Adenia and Passiflora, and Deidamia clematoides and Barteria fistulosa (of the Paropsieae) release appreciable amounts of prussic acid on wounding. They contain the gynocardin-like glucosides deidaclin (first named deidamin) and barterioside and, most probably, also gynocardin itself (). The occurrence of this highly characteristic type of cyanogenic glucosides points to a rather intimate relationship between Passifloraceae and Flacourtiaceae-Pangieae. Besides cyanogenic glucosides other toxic principles seem to be present in some members of the family; a toxalbumin, modeccin, was reported as a constituent of Adenia (= Modecca) digitata.
Notwithstanding their often toxic nature several species of Passiflora produce edible 'Passion Fruits' (see ).
Leaves and stems of the non-cyanogenic, temperate American species Passiflora incarnata are used in medicine as a sedative drug; Herba Passiflorae contains harman and related simple indolic alkaloids. Such alkaloids are also present in other species of Passiflora. The phenolic constituents of Passifloraceous plants are still very incompletely known.
The so-called tannin cells of plant anatomists seem to contain catechins and leucoanthocyanins rather than true tannins. True tannins are lacking in the family or at the most are present in small amounts. Leaf flavonoids are represented by glucosides of kaempferol and quercetin (but not of myricetin) and especially by C-glykoflavones like saponaretin (= isovitexin), vitexin and orientin.
On the whole our knowledge of chemical characters of Passifloraceae is still very restricted. However, the common occurrence and the very peculiar nature of the gynocardin-like cyanogenic glucosides accentuate a Flacourtiaceous relationship. For a summary of phytochemical literature and references see . — R. HEGNAUER.