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Published In: Tableau Encyclopédique et Methodique ... Botanique 1: 379, t. 167, figs. a–m. 1792. (13 Feb [t. 167] & 30 Jul [p. 379] 1792) (Tabl. Encycl.) Name publication detailView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 10/2/2009)
Acceptance : Accepted
Project Data     (Last Modified On 12/2/2016)
Notes:

Gaertnera comprises 85 species with 4 distinguished varieties plus 1 presumed hybrid taxon of shrubs and small trees found widely in the Old World tropics, in humid evergreen forests from sea level to over 2000 m elevation (Malcomber & Taylor 2009; Taylor et al. 2014). Gaertnera and the Neotropical genus Pagamea Aubl. comprise the tribe Gaertnereae. Gaertnera can be recognized within the Rubiaceae by its woody habit; its generally well developed tubular stipules; its distinctive ridges or wings that encircle the sides and bottom of the petiole and often extend upward onto the stipule sheath; its bracteate, basically cymose inflorescences variously borne in terminal, pseudoaxillary, axillary, and/or supra-axillary position; it calyx limb with a well developed tube; its salverform to funnelform, white, pink, or occasionally red corollas with 4 or 5 valvate lobes; its 2-locular ovary that is superior in flower; and its superior, purple-black, drupaceous fruit with 2 pyrenes. The superior position of the ovary is unusual in the Rubiaceae, and apparently secondarily derived (Igersheim et al. 1994). Gaertnera is also notable for the variation in its breeding biology, with the species of Africa, Madagascar, the Mascarenes, and Sri Lanka for which the biology is known all distylous, but the species of southeastern Asia apparently all dioecious with this latter condition presumably derived (Malcomber 2002).

Van Beusekom (1967) adopted a broader species concept than here, and in particular circumscribed Gaertnera vaginans as a widespread, morphologically and biologically variable species with two subspecies. He included in G. vaginans plants of Africa, Madagascar, Sri Lanka, and southeastern Asia, all with cylindrical stipules that closely encircle the stem, 5-merous flowers, reduced calyx lobes, and fruits of average size and shape. However the inflorescence arrangement varied from subcapitate to diffusely cymose and the breeding biology included homostyly, distyly, and dioecy. His subsp. vaginans comprised the distylous plants, found in Africa, Madgascar, and Sri Lanka; his subspecies junghuhniana comprised the dioecious plants, found in southeastern Asia. In his circumscription this polymorphic species thus ranged across several distinct biogeographic regions and was circumscribed by potentially ancestral characters. Molecular sequence data indicate that the plants grouped as G. vaginans by van Beusekom are a polyphyletic group, with its members distributed among several clades (Malcomber & Taylor 2009). The molecular data agree with a classification based on morphological characters and breeding system. Here the plants of van Beusekom's "Gaertnera vaginans" group are treated in 12 species, each found in a single biogeographic region: G. alstonii, G. aphanodioica, G. arenaria, G. belumutensis, G. capitulata, G. junghuhniana, G. kochummenii, G. longivaginalis, G. paniculata, G. ramosaG. sralensis, and G. vaginans.

Note to Users: The images and specimens that TROPICOS displays on this genus page are those that are identified only as Gaertnera sp.; specimens and images that are identified with a species name are displayed on the corresponding species page.

Authors: S.T. Malcomber & C.M. Taylor.
The content of this web page was last revised on 28 August 2014.
Malcomber web page http://www.csulb.edu/~smalcomb/
Taylor web page http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

Distribution:

Paleotropics: Evergreen moist vegetation, usually in forest understory, at 0--2000 m in Africa (Senegal, Sierra Leone, Guinea [-Konachry], Benin, Mali, Liberia, Ivory Coast, Burkina Faso, Ghana, Togo, Nigeria, Cameroon, Central African Republic, Democratic Republic of Congo, Republic of Congo, Equatorial Guinea, Gabon, Angola, Zambia), Madgascar, the Mascarenes (Mauritius, Réunion), Sri Lanka, and continental southeastern Asia (Thailand, Cambodia, Vietnam, Malaysia), Sumatra (Indonesia), and Borneo (Brunei, Malaysia, Indonesia).

References:

 

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            Trees or shrubs, up to 15(--20) m tall, glabrous to variously pubescent, sometimes drying grayish green, brown, gray, chestnut, reddish brown, or with a distinctive orange cast. Branches flattened to tetete or quadrangular, 0.5--15 mm diam.; internodes 0.1--26 cm, smooth or with 2 to 4 longitudinal ribs, sometimes corky (G. alata). Leaves sessile to petiolate, decussate, paired or rarely ternate, isophyllous to a little anisophyllous; blade 0.5--55 x 0.1--20 cm, linear-lanceolate to elliptic, elliptic-oblong, or cuneiform, margins flat or infrequently crisped; secondary veins visible or sometimes not visible below, eucamptodromous, spreading and arched or infrequently nearly straight and ascending at an acute angle; domatia absent or present as pilosulous or hirtellous, tuft- or crypt-domatia in axils of secondary veins; petioles 0.2--10 cm , smooth to occasionally furrowed or rarely winged, smooth or usually encircled on sides and below by ridges or wings, these often extending onto stipules. Stipules 0.1--75 mm, tubular and open at top in bud to fused at top and calyptrate, cylindrical to infrequently funnel-shaped, entire or splitting along 1 side to form a spathaceous structure, splitting on 2 sides to form 2 usually intrapetiolar segments, or rarely splitting on 4 sides into 4 spathulate parts (G. furcellata, G. microphylla), drying membranaceous to coriaceous, variously caducous, deciduous through fragmentation, or persistent, usually with 4 longitudinal ribs or wings arising below petioles and extending along sheath to lobes, sometimes with 2 additional ribs or wings; apex entire or with the 1--4 incisions described above, marcesent (i.e., becoming hardened) to fragmenting or infrequently persistent; lobes none or 4, up to 20 mm, deltate to filiform; additional setae none or several to numerous, to 20 mm. Inflorescences terminal on developed stems, sometimes borne on short axillary stems, or rarely axillary or terminal on supraaxillary stems, cymose to compound-cymose, paniculiform, subcapitate, reduced to 1 or a few flowers, or rarely spiciform, erect to occasionally pendulous, sessile to pedunculate, green, white or pink, bracteate or rarely ebracteate (G. alata); peduncle to 15 cm; branched portion up to 25 x 30 cm, pyramidal to corymbiform-rounded, subglobose, or rarely cylindrical, branched to as many as 6 orders, lax to congested; axes dichasial or rarely scorpioid (G. divaricata); bracts subtending basalmost axes triangular to linear or sometimes resembling reduced leaves or stipules (G. microphylla), rarely grouped into an involucre (G. cuneifolia, G. microphylla); bracts subtending higher-order axes up to 30 mm, deltate to linear, ovate, or trifid, usually grading in size and shape between basalmost bracts and bracteoles; bracteoles reduced to developed, inserted on pedicel and/or at base of calyx, rarely enlarged and bright white (G. phyllosepala, G. phyllostachya). Supra-axillary reproductive branches rarely present (G. diversifolia, G. inflexa), paired, flexuous, with leaves well developed to reduced. Flowers sessile to pedicellate, 4- to 5(6)-merous, dioecious or bisexual and heterodistylous. Calyx limb cup-shaped, urceolate, or campanulate, 1--20 mm wide, outside glabrous or variously pubescent, inside sometimes with a distinct ring of trichomes, truncate to denticulate or lobed, lobes rounded to triangular or linear, equal to markedly unequal, up to 30 mm, sometimes petaloid in color and texture (G. phyllosepala, G. phyllostachya); corolla white or infrequently pink, red, orange, or blue, clavate to rhomboidal or obclavate in bud, at anthesis salverform, infundibuliform or campanulate, 2--30 mm, outside glabrous or variously pubescent, inside glabrous or villous inside tube, tube entire or rarely fenestrate (G. cooperi), lobes 1--10 mm, narrowly triangular to ovate-oblong, glabrous adaxially, apically rounded to acute or rarely expanded and cucullate (G. cooperi), abaxially smooth or rarely with a thickened subapical appendage  (G. edentata); stamens inserted in corolla tube, anthers 1.5--4 mm, narrowly oblong, dithecal, dehiscent by longitudinal slits, sessile or with developed filaments to 8 mm, in long-styled flowers positioned below the stigmas and included to partially exserted, in short-styled flowers position above the stigmas and included to exserted, in staminate flowers positioned near middle of corolla tube to exserted, in pistillate flowers staminodes present or absent, positioned in lower part of corolla to corolla throat. Ovary superior, 2-locular, 2-celled, with 1 erect basal ovule in each cell; style filiform, glabrous or pubescent, stigmas 2, linear-clavate, often flattened, in long-styled flowers these positioned above the anthers and exserted, in short-styled flowers these positioned below the anthers and included, in staminate flowers pistillodes developed or reduced and positioned in lower part to middle of corolla tube, in pistillate flowers these developed and positioned in lower to upper part of corolla tube. Fruit a drupe, blue to violet-black or reportedly sometimes whitened, globose to ellipsoid,  obovoid, or didymous, smooth or infrequently ridged, 5--28 x 5--16 mm, glabrous or rarely pubescent; pyrenes 2 per drupe or sometimes 1 apparently by abortion or incomplete pollination, spherical or hemispherical to wedge-shaped, ± smooth to finely fissured, rugose, and/or deeply fissured, endosperm entire to invaginated or ruminated.

 

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Key to Species of the "Gaertnera vaginans" Complex
1. Stems and stipules pilosulous to hirtellous, tomentulose, and villous or stipules sometimes puberulous; plants dioecious.
    2. Leaves elliptic-oblong to oblanceolate or elliptic; inflorescence corymbiform; peduncles 3--5 cm long; Borneo....Gaertnera alstonii
    2'. Leaves elliptic to oblanceolate; inflorescence subglobose, sessile or with peduncles to 1.4 cm long; Borneo....Gaertnera capitulata
1'. Stems and stipules glabrous or puberulent, or stipules sometimes pilosulous in G. longivaginalis; plants distylous or dioecious.
    3. Inflorescences subglobose, sessile or with peduncles to 3.5 cm long.
        4. Plants drying with green to grayish green cast; continental Southeast Asia ....Gaertnera sralensis
        4'. Plants drying with orange cast. 
            5. Calyx truncate or with lobes to 0.3 mm long; continental Southeast Asia....Gaertnera belemutensis
            5'. Calyx lobes 1--3.5 mm long; continental Southeast Asia....Gaertnera kochumennii
    3'. Inflorescences corymbiform to pyramidal, sessile or with peduncles to 6 cm long.
        6. Plants dioecious, with unisexual flowers (flowers appearing homostylous in G. aphanodioica). 
            7. Stipules drying membranous, with lobes 1--2.5 mm long; inflorescences several-flowered, with ca. 5--10 flowers; continental Southeastern Asia....Gaertnera ramosa
           7'. Stipules drying chartaceous, with lobes 1--7 mm long; inflorescences many-flowered, with more than 10 flowers. 
               8. Corolla white, tube 6--9 mm long; Borneo....Gaertnera aphanodioica
               8'. Corolla pale green to white, tube 2.5--5 mm long; continental Southeastern Asia....Gaertnera junghuhniana
        6. Plants distylous, with bisexual flowers. 
            9. Stipules drying membranous, with lobes 1--8 mm long; corolla tube 4--6 mm long; West and Central Africa....Gaertnera longivaginalis
            9'. Stipules drying chartaceous, with lobes 0.5--5 mm long. 
                10. Corolla tube 3--4 mm long, externally densely puberulent or tomentose; stipule lobes 0.5--1.2 mm long; West and Central Africa....G. paniculata
                10'. Corolla tube 4--16 mm long, externally glabrous, scabrous, or sparsely puberulent; stipule lobes 0.5--5 mm long. 
                    11. Corolla tube 10--16 mm long; stipule lobes 2.5--5 mm long; Madagascar....Gaertnera arenaria
                    11'. Corolla tube 4--6 mm long; stipule lobes 0.5--2.5 mm long; Sri Lanka....Gaertnera vaginans

 

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