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Published In: Prodromus Florae Nepalensis 136. 1825. (1 Feb 1825) (Prodr. Fl. Nepal.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 4/12/2020)
Acceptance : Accepted
Note : Tribe Palicoureeae
Project Data     (Last Modified On 5/5/2021)
Notes:

The pantropical genus Geophila is found almost worldwide in moist tropical regions, and includes perhaps 20 species of creeping herbs with long trailing stems, adventitous roots, and generally ovate to reniform leaves borne on well developed petioles. These plants have terminal, capitate to congested-cymose, bracteate inflorescences generally borne on well developed peduncles, rather small, 5-merous, homostylous flowers, white corollas with lobes that are valvate in bud, a 2-locular ovary with 1 basal ovule in each locule, and small drupaceous fruits with 2 hemispherical (planoconvex) pyrenes. The plants often cover a local area of forest floor, and appear to be a colony of separate plants but actually represent one or a few trailing, branched plants. Geophila is one of relatively few pantropical genera of Rubiaceae. The center of diversity is in Africa, and another center is in the Neotropics The neotropical species Geophila repens and the Paleotropical species Geophila uniflora are the most widespread and commonly collected species; these were regarded as a single pantropical species until recently, when the molecular analyses of Razafimandimbison et al. (2014) found the neotropical plants to be a distinct  lineage from the paleotropical plants. Taxonomic separation of the paleotropical and neotropical species was previously suggeted based on morphological differences by Verdcourt (1976). 

The fruits of Geophila species are usually red, but a few species have blue to purple-black fruits; generally one or two species with blue or purple-black fruits are found in each continental region.. The pyrenes of Geophila repens are distinctive in being longitudinally twisted, by about 30 degrees, and this pyrene form has sometimes been generalized to the genus but it is not found in most of the other species, actually. Geophila repens appears to be homostylous, rather than distylous as in most Palicoureeae genera, but this has not been studied in detail across its range. Geophila uniflora is also homostylous (pers. obs.), and as with fruit form, this floral biology has been attributed to the entire genus but that has not actually been confirmed. The corollas of Geophila are often quite brightly white, and show up well in a shaded forest understory. 

The habit of Geophila is distinctive within Rubiaceae and the tribe Palicoureeae, and but it is not unique. In the Neotropics, several species of Palicourea have a similar trailing habit and inflorescence form, though these have elliptic leaves that are more often obtuse to truncate at the base than cordate as in Geophila. In Africa, Hymenocoleus is similar in habit often in leaf form, and usually in other features, but Hymenocoleus differs fro from Geophila in the membranaceous sheath on its nodes.Geophila was circumscriibed more broadly in Africa, and included those species until Robbrecht separated Hymenocoleus in 1975 based on morphological analysis; subsequently, molecular analyses (e.g., Razafimandimbison et al. 2014) have supported their separation. In Madagascar, Puffia is similar to Geophila, but can be separated by its bright yellow fruits and distylous flowers. 

Berger & Schinnerl (2019) detailed some of the chemistry of secondary metabolites in this group, in Psychotria s. str. and the genera of Palicoureeae, and found chemical differences between Psychotria, which lacks alkaloids and contains tannins, and the genera of Palicoureeae, with some characteristic types of alkaloids and without tannins.Within this pattern, they found Geophila characterized by alstrostine metabolites.

The nomenclatural history of this small genus of rather tiny herbs is complicated. The Rubiaceae genus Geophila D. Don was described and clearly characterized in 1825, but the name Geophila Bergeret was published before then (1802) for a genus of monocots.This made the Rubiaceae genus Geophila's name an illegitimate later homonym. This illegitimate name was not a problem for some authors; in particular, Mueller (1881) included Geophila in his circumscription of Mapouria as a new section, so it did not need a legitimate name. Later Geophila was separated and it did need a name, and this problem was noticed and solved in different ways. Wight noted the problem and published the legitimate replacement name Carinta W. Wight (1905), and included only one species that he considered pantropical, Carinta repens.Wight published this in a flora checklist of Guam, and it was apparently not widely noted right away. At almost the same time, Standley separately studied Geophila D. Don and resolved the name problem by publishing the replacement name Geocardia Standl. in 1914, but this name was superfluous and illegitimate because Carinta had previously been published for this group. Standley published 8 new combinations for species names in Geocardia, with most of them neotropical but one from Africa (and one of his neotropical species is now included in Palicourea, and another in Coccocypselum). The name Carinta was then used in several taxonomic studies of African and Malagasy species in the 1960's, with new combinations published for the African Geophila species, but it was only used once for one species by Neotropical authors. After that, the status of the name Geophila D. Don was addressed by special nomenclatural action, and the name Geophila D. Don was formally conserved over Geophila Bergeret. This makes Geophila the correct name for this group, and Carinta is now rejected because it is homotypic with the conserved name (Art. 14.4)

The identity of the type species of Geophila is also complicated, and has been interpreted variously and not entirely clear. The genus was published with one species treated, Geophila renifolia, but with three species listed: Psychotria herbacea L., Psychotria macropoda Ruiz & Pav., and Psychotria gracilis Ruiz & Pav. Most authors have considered the one species treated by Don in Geophila to be the type species, but some authors (including some authors who cite Geophila reniformis as the type) also consider the type of the genus to be undesignated because three species were listed.  

Additonally with regard to the identity of the type species of Geophila, some of the early names that apply to this have been interpreted differently. There are two oldest, clearly legitimate names for species in this group, Rondeletia repens L. (1759), based on a lectotype from Jamaica, and Psychotria herbacea Jacq. (1760), based on a lectotype from India. A third name dates from the same period, and has been problematic as to its identity and status. Psychotria herbacea L. (1762) has generally been regarded as an illegitimate later homonym of Psychotria herbacea Jacq.and nomenclaturally distinct, but a few authors have considered Linnaeus's name to be an unattributed citation of Jacquin's name. Linnaeus included in his protologue of Psychotria herbacea L. six different elements from both the Antilles and Asia, with no mention of Jacquin or his name. Linnaeus's name has been applied variously using the Antillean or the Asian elements, and there is a single specimen in the LINN herbarium that has been considered to have come from Browne in Jamaica and been regarded as the holotype (Verdcourt, 1976; LINN herbarium curation). Because there is no clear or otherwise explicit connection in Linnaeus's protologue to Jacquin's name, and the two names have different apparent type elements, these have been considered two different name by most authors (e.g., Williams, 1973; Verdcourt, 1976; Howard, 1989; Linnaean Typification Project) following the practice of determining the identity and status of a name using the information in the protologue without positing additional possiblities (Art. 9.4). In contrast, a few authors (e.g., IUCN Appendix III) have posited that even without direct evidence of a connection, Linnaeus's name is probably an inaccurate, incomplete citation of Jacquin's name, and they therefore have regarded citations of Linnaeus's name as being inaccurate citations of Jacquin's name. The view taken on this issue changes the identity of the presumed type species of Geophila, so these divergent interpretation are problematic although neither view results in taxonomic changes. Geophila reniformis D. Don. was published based explicitly on Psychotria hebacea L., so its status and identity depend on the status and identity of that name. When Psychotria herbacea L.is regarded as an illegitimate, separate name, the name Geophila reniformis is a legitimate replacement name that is, if Browne's is the type material, a name for the widespread neotropical species and a synonym of Geophila repens. When Psychotria herbacea L. is regarded as an inaccurate citation of Psychotria herbacea Jacquin, then Geophila reniformis is a synonym of Geophila uniflora (as far as can be determined from general survey of published treatments, but the paleotropical names have not been reviewed in detail here). 

Geophila has not been studied comprehensively in detail. It was studied in a thesis by Es (1999), but that work was never formally published and predated most molecular methods. Geophila has been treated in various floras on several continents; in the Neotropics, relatively detailed treatments are available by Es & Piesschaert (in Taylor & Lorence, 2012), Taylor & Steyermark (in Taylor et al., 2004), Williams (1973), and Steyermark (1974). The species taxonomy of Es & Piesschaert patially differs from that of Taylor and Steyermark; in particular, the latter authors have considered Geophila gracilis to be a separate species from Geophila repens, while Es & Piesschaert synonymized it based on numerical taxonomic analysis. In the Africa, this genus was reviewed briefly by Verdcourt (1975, 1976). 

Note: the databasing of species and names below is provisional and incomplete, especially for paleotropical species. The names treated here for African species are based on the African Plants Database, and have not been studied in detail by this Tropicos project. 

Author: C.M. Taylor.
The content of this web page was last revised on 6 May 2021.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

Distribution: Understory of lowland wet forest, southern Mexico and Greater Antilles to Bolivia and northern Argentina, and widespread in tropical Africa, Madagascar, southern and southeastern Asia, and the Pacific region.
References:

 

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Creeping perennial herbs, unarmed, terrestrial, with raphides in the tissues, with trailing stems rooting at nodes, with reproductive stems short and ascending. Leaves opposite, petiolate, entire and cordiform, with higher-order venation not lineolate, without domatia; stipules interpetiolar, triangiular or 2(3)-lobed and sometimes marginally erose, generally erect and valvate or imbricated in bud, persistent. Inflorescences  terminal and pseudoaxillary, subcapitate to shortly cymose, 1--several-flowered, pedunculate, bracteate. Flowers sessile to shortly pedicellate, bisexual, homostylous, protandrous, small, fragrant unknown, apparently diurnal; hypanthium ellipsoid to turbinate; calyx limb developed, (4)5(7)-lobed, without calycophylls; corolla salverform or funnelform, white, internally pubescent in upper part of tube, tube generally straight and cylindrical at base, lobes (4)5(7), triangular, valvate in bud, without appendages; stamens (4)5(7), inserted near or above middle of corolla tube, anthers ellipsoid to oblong, dorsifixed near middle, opening by linear slits, without appendages, included; ovary 2-locular, with ovules 1 in each locule, basal; stigmas 2, included. Fruit drupaceous, subglobose to ellipsoid, fleshy or juicy, at maturity red or purple-black, with calyx limb persistent; pyrenes 2, 1-locular, hemispherical (i.e., planoconvex), bony, dehiscent by pre-formed germination slits, plane or with a medial groove adaxially; seeds 1 per pyrene, hemispherical to ellipsoid, seed coat without alcohol-soluble red pigment, endosperm entire or perhaps ruminated.

 

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