Rubiaceae of the New World

By Piero Delprete and Rocio Cortés
 

AUGUSTA Pohl

Augusta longifolia                                                Photo  P. Delprete Serra Dourada, Goias, Brazil

Synonyms: Augustea A. P. de Candolle (orth. var.), non Augusta Leandro; Bonifacia Manso ex Steudel; Lindenia Bentham; Schreibersia Pohl (nomen); Siphonia Bentham; Ucriana sensu K. P. J. Sprengel, non Ucriana Willdenow (= Tocoyena Aublet).

Rheophytic shrubs; raphides absent; axillary thorns absent. Stipules interpetiolar, free at base or interpetiolar, connate at base, narrowly triangular or deltoid, persistent. Leaves opposite, short-petiolate or subsessil; blades elliptic, oblanceolate or lanceolate, chartaceous or thinly coriaceous; foliar pellucid glands absent; domatia absent. Inflorescence terminal, not frondose, cymose, pauciflorous, corymbose. Flowers bisexual, protandrous. Calyx extremely reduced (less than 2 mm), persistent; lobes 5, linear; small or long. Calycophylls absent. Corolla tubular or narrowly infundibuliform, actinomorphic or zygomorphic, flower bud laterally bent at apex (corolla lobes), white to cream-white or red; tube externally glabrous, internally puberulent, without a pubescent ring inside; orifice annular thickening absent; lobes 5, imbricate (tube non reduplicate) or left-contorted, ovate, elliptic or lanceolate, margin entire, rounded or acute at apex. Stamens alternate to the corolla lobes, exserted just beyond the corolla; anthers narrowly elliptic, acute at base, acute at apex, dehiscing by longitudinal slits, dorsifixed near the middle; filaments attached near the mouth of the corolla tube, free at base, filiform, short (anthers subsessil), equal, glabrous. Pollen colporate, apertures 3, exine surface reticulate or minutely reticulate, released as monads. Style exserted well beyond the corolla, filiform, clavate, erect-puberulent; lobes 2, oblong. Ovary inferior, 2-locular, obconical; placentation axile, peltate to the entire lenght of the septum, ovules many per locule. Fruit a septicidal capsule, dehiscing basipetally, the valves secondarily splitting at apex, thinly woody. Seeds horizontal, minute, 3-5-angular; wings absent.

Geographic distribution: Southern Central America, Brazilian Atlantic coast and Brazilian planalto. A genus of 4 species, with 2 species occuring in the South Pacific, and 2 in the neotropics.

Number of species: 2.

References: J. H. Kirkbride, Manipulus rubiacearum - VI. Brittonia 49: 354–379. 1997; P. G. Delprete, Revision and typification of Brazilian Augusta (Rubiaceae, Rondeletieae), with ecological observations on the riverine vegetation of the cerrado and Atlantic forests. Brittonia 49: 487–497. 1997.