Rubiaceae of the New World

By Piero Delprete and Rocio Cortés
 

HINTONIA Bullock

Hintonia latiflora              Open flower and Flower bud  Puebla, Mexico                       Photo H. Ochoterena

Shrubs, or small to medium-sized trees; raphides absent; axillary thorns absent. Stipules interpetiolar, free at base or interpetiolar, connate at base, broadly triangular, persistent or subcaducous. Leaves opposite, long-petiolate or short-petiolate; blades ovate, elliptic, oblong or lanceolate, chartaceous or papyraceous; foliar pellucid glands absent; domatia sparse or dense tufts of hairs, or absent. Inflorescence axillary, cymose, pauciflorous or uniflorous. Flowers bisexual, protandrous. Calyx tube absent, lobes connate or free at base, caducous; lobes 6 to 8, narrowly lanceolate or linear, long. Calycophylls absent. Corolla campanulate or narrowly campanulate or broadly infundibuliform, actinomorphic, white to cream-white, greenish-yellow, yellowish-white, yellowish-green, pink, violet, purple, yellow-green to pale green; tube externally glabrous or basally pubescent, internally glabrous, without a pubescent ring inside; orifice annular thickening absent; lobes 6 to 8, imbricate (tube reduplicate), broadly triangular, margin entire, rounded at apex. Stamens alternate to the corolla lobes, partially exserted (only tips exserted); anthers linear, round at base, round at apex, dehiscing by longitudinal slits, basifixed; filaments attached at base of the corolla tube, basally connate (forming a minute tube at base of the corolla), slender, long, shorter than corolla tube, equal, glabrous. Pollen colpate, apertures 3, exine surface echinate-perforate, released as monads. Style exserted just beyond the corolla, terete throughout, not fleshy, glabrous, lobes absent, stigmatic surface linear along style. Ovary inferior, 2-locular, ovoid or obovoid; placentation axile, placenta peltate to the entire lenght of the septum, ovules many per locule. Fruit a septicidal capsule, dehiscing basipetally, the valves secondarily splitting at apex or not, thickly woody. Seeds descentingly imbricate, large, dorsoventrally compressed, elliptic to narrowly elliptic in outline; wings concentric with entire margin.

Geographic distribution: Northern Central America (up to southern Mexico).

Number of species: 4.

References: A. A. Bullock, Hintonia genus novum. Hooker's Ic. Pl. 33: t. 3295. 1935.