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Published In: Hooker's Icones Plantarum 33(4): 1, sub t. 3295. 1935. (Dec 1935) (Hooker's Icon. Pl.) Name publication detailView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 4/9/2021)
Acceptance : Accepted
Note : Tribe Chiococceae
Project Data     (Last Modified On 4/23/2021)
Notes:

HIntonia includes 3 species of shrubs and small trees found widely in Mexico and northern Central America and sporadically to Costa Rica. All three of its species are found together in southern Mexico and Guatemala, and were treated together in Lorence et al. ( 2012). Hintonia is characterized by its woody habit; medium-sized petiolate leaves; triangular short stipules; showy, 6- or 8-merous flowers that are solitary in the axils of a few nodes below the stem apex; broadly funnelform white corollas that are plicate in bud with thinly imbricated lobes; stamens inserted near the base of the corolla and coherent or weakly fused at their bases; ellispoid, woody, deeply septicidal capsules; and numerous, medium-sized, discoid seeds with concentric marginal wings. The stipules are persistent with the leaves in Hintonia lumana, and even after the leaves and often become indurated in the species of dry vegetation. The flowers are spreading to pendulous, and fragrant and apparently nocturnal. The calyx limb is divided nearly to the base, and the lobes are well developed and often appear free. The buds are inflated and plicate, with the sinus portions "out-folded" and the lobes "infolded" along their midribs. The anthers are relatively large (for Rubiaceae). The capsules are distinctive in their enlarged disk portion, which extends above the calyx and gives many capsules an appearance of being seim-inferior. Hintonia latiflora is the most widely distributed and commonly collected species. Ochoterena-Booth (2000) detailed the local use of Hintonia latiflora as medical remedy, for fevers in general and for malaria. This species is called Colpache in Mexico, or sometime quina. As a remedy, the bark is boiled and used as a poultice or drunk as a tea. Some medicinally active compounds are found in this bark, and it is also commercially marketed as an herbal remedy.

Two of the species of Hintonia are found in seasonal vegetation, and these are characterized by stems with some shortened internodes and sometime with brachyblasts, and these are presumably at least sometimes deciduous. The stem growth of Hintonia octomera is distinctive in its regularly repeated pattern of several developed internodes then several brachyblasts. In contrast, Hintonia lumana has regularly well developed internodes and is found in evergreen, often quite wet vegetation. The leaves variously lack domatia or have these, as either tufts of pubescence or crypt-type structures. Thus, this genus is difficult to characterize vegetatively. Hintonia is similar to Exostema and Solenandra, which differ in several reproductive features including their salverform corollas.

The floral biology of Hintonia is protrandrous, but beyond this its condition is not clear as detailed by Ochoterena-Booth (Lorence et al., 2012: 118). She noted that released pollen is found on the flowers as they open, as in most protandrous Rubiaceaed, and sometimes even within the buds. She also noted that the flowers generally appear homostylous but the styles vary in length within flowers studied and some show dimorphic pollen sizes, and this variation could represent observations of flowers at different developmental stages of the style and with some undeveloped pollen but that distylous could not yet be ruled out in HIntonia. The flower buds are inflated and plicate, with the sinus portion "outfolded" and the lobes "infolded" along their midribs. The corolla lobes appear valvate but are thinly imbricates.

The ovary of Hintonia was studied by Aiello (1979: f69, fig 58) and Ochoterena-Booth (2000), who found each of the two locules largely filled with a spongy placenta attached along the length of the septum and bearing numerous ovules. In the capsule, each locule produces ca. 50 seeds that are imbricated and vertical. Ochoterena-Booth noted that Aiello's characterization of the capsule dehiscence as only septicidal was incomplete, and that secondarily the enlarged woody disk and upper part of the septum split loculicidally though shortly; this dehiscence is similar to that of related genera except the capsules of those genera open loculicidally more widely (e.g., Coutarea).

Hintonia is similar to Coutarea, which differs in its zygomorphic flowers with the stamens exserted and all held on the lower part of the flower and strongly flattened capsules. Hintonia is also similar to Exostema, which differs in its flowers with well exserted stamens, salverform corollas with cylindrical tubes, and smaller capsules.

Paudyal et al. (2018) included two species of Hintonia in their molecular analysis, and found these to form a monophyletic group related to Coutarea, Coutareopsis, and several other genera with similar capsules.

Author: C.M. Taylor.
The content of this web page was last revised on 23 April 2021.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

Distribution: Seasonal forest, dry scrub, and evergreen to wet forest at 0-2200 m, widely from northern Mexico into Central America (El Salvador, Guatemala, Costa Rica).
References:

 

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Shrubs and small trees, unarmed, terrestrial, without raphides in the tissues, sometimes with short-shoots, sometimes with corky bark, sometimes resinous at apex. Leaves opposite, petiolate, entire, with the higher-order venation not lineolate, sometimes with pubescent or crypt-type domatia; stipules interpetiolar, triangular, acute, erect and perhaps imbricated in bud, persistent and often becoming indurated. Inflorescences axillary at several nodes below stem apex, flowers solitary and spreading to pendulous, pedunculate, peduncle sometimes articulated, ebracteate or irregularly bracteate. Flowers pedunculate, bisexual, protandrous, perhaps homostylous, medium-sized, fragrant, apparently nocturnal; hypanthium obconic; calyx limb developed, deeply 6- or 8-lobed, without calycophylls; corolla in bud inflated, plicate, and yellow to pale green, at anthesis broadly funnelform and white sometimes flushed with pink, medium-sized (3-12 cm), glabrous inside, lobes 6 or 8, triangular, rather short, in bud thinly imbricated (quincuncial), spreading at anthesis, without appendage; stamens 6 or 8, inserted at base of corolla tube, filaments shorty connate at base, anthers narrowly oblong, basifixed, dehiscent by linear slits, included to shortly exserted, sagittate at base, without appendage at top; ovary 2-locular, with ovules numerous in each locule, on axile placentas, stigma 1, cylindrical, sometimes bilobed, partially exserted. Fruit capsular, ellipsoid to subglobose, laterally weakly flattened, septicidally dehiscent from apex then shortly loculicidal, with valves eventually fully separating, rather small (1.5-3.5 cm long), woody, smooth or ridged, sometimes lenticellate, with calyx limb deciduous; seeds numerous per locule, discoid to elliptic, flattened, medium-sized (4-8 mm), marginally with concentric wing, entire, densely reticulate.

 

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 Key to Species of Hintonia; from Lorence et al., 2012

1. Stems with developed internodes along their length then short-shoots (brachyblasts) at apex; apex of leaf blade mucronate; flowers 8-merous....Hintonia octomera

1'. Stems with internodes regularly developed, or irregularly developed and shortened; apex of leaf blade acute to acuminate; flowers 6-merous. 

     2. Leaves decussate; bracts free; plants of seasonal to dry forest and scrub..... Hintonia latiflora

     2'. Leaves distichous; bracts connected around stem by stipuliform structures; plants of evergreen to wet forest..... Hintonia lumana

 
 
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