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Published In: Systema Naturae, Editio Decima 2: 906 [as Psycothria], 929, 1364. 1759. (7 June 1759) (Syst. Nat. (ed. 10)) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 4/30/2015)
Acceptance : Accepted
Note : Belongs to Tribe Psychotrieae
Project Data     (Last Modified On 10/5/2020)
Notes:

The genus Psychotria is found world-wide in tropical regions, and is one of the largest genera of flowering plants in the world with perhaps 1500--2000 species. It is characterized by a generally woody habit, stipules of various forms that are often bilobed and caducous, cymose inflorescences that are usually terminal, generally 5-merous distylous flowers, corollas with the lobes valvate in bud, mostly 2-locular ovaries, ovules solitary and basal in each locule, drupaceous fruits with usually 2 pyrenes that lack pre-formed germination slits, and seeds coats with an alcohol soluble red pigment. Psychotria has centers of diversity in the northern Neotropics, in tropical Africa, in Madagascar, in southeast Asia, and in the Pacific region. It has 100 or more species in each of these regions, and lacks any pantropically distributed species. Psychotria has notable species radiations one several humid tropical islands, including Cuba, Hispaniola, Madagascar, New Caledonia, and Tahiti. 

The information here gives a general overview of the systematics and morphology of this genus, and then detailed information about mainlhy the Neotropical species plus some species from Madagascar studied by Taylor and collaborators (Taylor, 2020; Taylor et al., 2020). For more comprehensive information in Tropicos about the Malagasy species of Paleotropical Psychotria, see the Madagascar Catalogue page for this genus (go to upper right of web page and click on "Chose Project", then choose "Madagascar").

Circumscription of Psychotria

The pantropical tribe Psychotrieae of the Rubiaceae belongs to the subfamily Rubioideae, and includes a large proportion of the 14,000+ species of this family. The circumscription of this tribe has been narrowed in recent years to include one broadly circumscribed genus, Psychotria, and the other genera that were traditionally included here have been separated in the tribe Palicoureeae, synonymized with Psychotria  (e.g., Razafmandimbison et al., 2014), or found to belong to other tribes. Also, Psychotria itself was traditionally circumscribed very broadly, to include several quite distinct lineages that have recently been separated from it. Its broad circumscription was due to its diagnosis by relatively small white flowers with valvate corolla lobes, ovules that are solitary and basal, and drupaceous fruits with generally 2 pyrenes; other genera were then separated from Psychotria based on having an unusual reproductive feature. The characters that diagnosed Psychotriea are basal in the large group of Rubiaceae to which it  belongs, however, so this diagnosis made Psychotria a paraphyletic group diagnosed by plesiomorphic features of its tribe, or tribal complex. 

It was recognized in the 20th century that this circumscription of Psychotria was problematic morphologically and in general too broad. This traditional broad circumscription was referred to as "Psychotria sensu lato",or  "Psychotria s. lat.". Studies using molecular data (Nepokroeff et al., 1999; Andersson, 2002, Barrabé et al., 2012, Razafimandimbison et al., 2014) complemented morpholgical studies (e.g., Taylor, 1996) to distinguish lineages within Psychotria s. lat., which were separated as genera. These studies also found several Paleotropical genera nested within the Psychotria clade, which was referred to then as "Psychotria sensu stricto" or Psychotria subg. Psychotria. Genera that have now been synonymized within the new circymscription of Psychotria are from the Indian and Pacific Ocean regions and include Amaracarpus Blume, Straussia A. Gray, Psathura Comm. ex Juss., Hydnophytum Jack, and Myrmecodia Jack, Apomuria Bremek., Cremocarpon Boivin ex Baill., Grumilea Gaertn., Pyragra Bremek., and Trigonopyren Bremek. (Andersson, 2002; Razafimandimbison et al., 2014; Taylor, 2020). These studies also confirmed the synonymy of the Neotropical genus Mapouria Aubl. with Psychotria, as noted by previous authors (e.g., Steyermark, 1972). 

The groups that have been separated from Psychotria s. lat. in the Neotropics are now treated as Ronabea Aubl. (Lasiantheae),  Coccochondra Rauschaert (incertis sedis),  Carapichea Aubl. (Palicoureeae), Eumachia DC. (Palicoureeae), and Notopleura (Benth.) Bremek. (Palicoureeae). In the Neotropics, Psychotria has been circumscribed to include part (Steyermark, 1972) or all (Mueller, 1881) of the Neotropical genus Palicourea, which created confusion over the identity of Psychotria. This "traditional" Psychotria s. lat. included two main group, Psychotria subg. Psychotria and Psychotria subg. Heteropsychotria. The first group, Psychotria subg. Psychotria, corresponds to today's Psychotria or Psychotria s. str. The group Psychotria s. str. plus Eumachia corresponds to Mapouria Aubl. of Mueller (1881). The species that were included in Psychotria subg. Heteropsychotria (almost) all belong to tribe Palicoureee, and almost all of them belong to Palicourea. Confusingly, the group composed of Psychotria subg. Heteropsychotria plus Palicourea was treated as "Psychotria" by Mueller (1881). The traditionally recognized genus Cephaelis is a synonym of Palicourea, and most of its Neotropical species belong to this genus or Carapichea now.

Neotropical Psychotria

Psychotria includes about 220 species in the Neotropics, which are found widely in humid and seasonal vegetation. One or more species are found in most sites, and generally a few species are sympatric in a given location. Psychotria species here are usually small to medium-sized shrubs, but range to medium-sized trees (e.g., Psychotria mexiae, Psychotria ortiziana) and rhizomatous herbaceous understory plants (e.g., Psychotria alfaroana). The flowers are generally small and white or yellow, and pollinated by insects. They generally appear to be diurnal, but a few species may be nocturnal (e.g., Psychotria ortiziana). The fruits are consistently orange or red in the Neotropical species, although the fruit color varies widely in the Paleotropics. Most of the species are distylous across most of their ranges, but populations of some species are apparently monomorphic in some sites. (e.g., Sakai & Wright, 2008).

Many species of most Psychotria species characteristically dry with a gray, brown, reddish brown, or blackened color; this drying color has been cited as diagnostic for the genus, but in fact it depends on specimen preparation and perhaps plant condition and some specimens of every species have dried green. Most species of Psychotria have distinctive stipules, which are caducous and leave a line of persistent colleters or trichomes on the stem at their insertion point. These trichomes are sometimes small and only visible with a hand lens but they are characteristic when present. A few species, however, have stipules that are persistent (e.g., Psychotria grandis) or colleters that are deciduous with the stipule. Many species of Psychotria have well developed foveolate domatia; the presence and sometimes the particular form of these is often distinctive for the species. Bacterial leaf nodules are present in some Psychotria species in Africa and Madagascar, but these have not been found in any Neotropical species. A few Psychotria species have been documented to hyper-accumulate nickel when growing on nickel-rich substrates (McCartha et al., 2019); the physiological and ecological function of this is unknown, and species of other Rubiaceae genera and other families are also hyper-accumulators. 

In the Neotropics, Psychotria has its center of diversity in southern Mexico and Central America; it was studied here in detail by Hamilton (1989, 1989, 1989). This genus has not been studied across the Neotropics, but a review is underway (Taylor & Hamilton, in prep.). Most of the Neotropical species are found in wet lowland forests, but some species range into montane elevations and a few are found in humid seasonal vegetation. The niche of this group was studied by Sedio et al. (2013), who found that overall the Neotropical species of Psychotria are found in slightly less humid habitats than the species of Palicourea. The most widespread and commonly collected Neotropical species is Psychotria carthagenensis. The Amazonian species Psychotria viridis is an enthonbotanical source of the hallucinogen DMT, and is part of the ayahuasca drug mixture. (The medicinal drug ipecac derives from a species that was formerly included in Psychotria but is now classified in a different genus, Carapichea ipecacuanha.

Psychotria and Palicourea can be separated by several characters, including vegetative features. Psychotria generally has caducous stipules, and in the species with persistent stipules these are acute to aristate at the tip; Palicourea has persistent stipules that are bilobed at least shallowly. Specimens of Psychotria often dry dark gray or reddish brown, though not always; Palicourea specimens generally dry green, although not always and a few species consistently dry blackened. Neotropical Psychotria fruits are orange to red at maturuity; Palicourea fruits are purple-black, blue, or white at maturity, and sometimes pass through an orange immature stage but those fruits eventually do turn purple-black. 

[Note: images posted by all MBG projects are included automatically here because they are identified as Psychotria sp., but are most are from Africa and Madagascar and not relevant to the taxonomic content of this page.] 

Author: C.M. Taylor, with collaboration from C.W. Hamilton.
The content of this web page was last revised on 5 October 2020.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

 

Distribution: Pantropical; in the Neotropics, Psychotria s. str. is found from northern Mexico and southern Florida though Central America and the Antilles to northern and north-central Argentina, from lowland wet and seasonal vegetation to upper montane forests.
References:

 

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Note: This is a morphological description for Neotropical Psychotria only; more variation and some different characters are found in Paleotropical Psychotria

Trees, shrubs, or suffrutescent subshrubs, unarmed, terrestrial, with raphides in the tissues. Leaves opposite, petiolate, entire, with higher-order venation not lineolate, often with pubescent or crypt-type domatia; stipules interpetiolar, fused around the stem, or calyptrate, triangular to ovate, rounded, or bilobed, generally valvate or imbricated in bud, caducous usually leaving a line of persistent basal trichomes on stem or infrequently persisting on distalmost nodes. Inflorescences terminal or occasionally pseudoaxillary, subcapitate to fasciculate, cymose, or thyrsiform, few- to multiflowered, sessile or pedunculate, bracteate. Flowers sessile to pedicellate, bisexual, distylous, protandrous, small to medium-sized, fragrant, diurnal or perhaps sometimes nocturnal; hypanthium ellipsoid to subglobose or turbinate; calyx limb developed, truncate to (4)5-lobed, without calycophylls; corolla salverform to funnelform, white to green, yellow, or flushed with pink, internally glabrous to pubescent and usually barbate in throat, lobes (4)5, triangular, valvate in bud, without or occasionally with appendages; stamens (4)5, inserted near middle or top of corolla tube, anthers narrowly oblong, dorsifixed near middle, opening by linear slits, without appendages, included to exserted; ovary 2-locular, with ovules 1 in each locule, basal; stigmas 2, included to exserted. Fruit drupaceous, subglobose to ellipsoid, juicy, at maturity orange to red, with calyx limb persistent; pyrenes 2, 1-locular, hemispherical (i.e., planoconvex), chartaceous to usually bony, generally without preformed germination slits, generally plane adaxially; seeds 1 per pyrene, hemispherical to ellipsoid, seed coat with alcohol-soluble red pigment, endosperm entire to ruminated. 

 

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