Rubiaceae of the New World

By Piero Delprete and Rocio Cortés
 

PINCKNEYA A. Richard in Michaux

Pinckneya bracteata          Photos P. Delprete Chatham County, Georgia, USA   Habit (left) Detail of flowers with calycophylls (above)

Shrubs, or small to medium-sized trees; raphides absent; axillary thorns absent. Stipules interpetiolar, free at base, narrowly triangular or narrowly ovate, subcaducous. Leaves opposite, long or short-petiolate; blades ovate or narrowly to regularly elliptic, stiffly or thinly coriaceous; foliar pellucid glands absent; domatia sparse tufts of hairs or absent. Inflorescence terminal, frondose, paniculate, sparsely branched. Flowers bisexual, protandrous. Calyx tube extremely reduced, with large lobes, caducous; lobes 5, linear, long. Calycophylls semaphyllous, 1 lobe per flower (rarely 2–3 lobes per flower), present in the first flowers of inflorescence branchlets, white to cream-white, pale pink, pink to lilac. Corolla tubular, actinomorphic, white to cream-white, pinkish-white, greenish-yellow or yellow; tube externally glabrous, internally sericeous, without a pubescent ring inside; orifice annular thickening absent; lobes 5, valvate, linear-lanceolate, margin entire, acute at apex. Stamens alternate to the corolla lobes, exserted well beyond the corolla; anthers narrowly elliptic, round at base, acute at apex, dehiscing by longitudinal slits, dorsifixed near the middle; filaments attached at base of the corolla tube, free at base, filiform, long, longer than corolla tube, subequal, glabrous. Pollen colporate, apertures 3, exine surface reticulate, released as monads. Style exserted well beyond the corolla, filiform throughout, glabrous; lobes 2, ovate. Ovary inferior, 2-locular, narrowly obovoid; placentation axile, placenta peltate to the entire lenght of the septum, ovules many per locule. Fruit a loculicidal capsule, dehiscing basipetally, thinly woody. Seeds horizontal, medium-sized to large, dorsoventrally compressed, hemi-elliptical in outline; wings lateral, lunate-orbicular in outline, with entire margin.

Geographic distribution: Extra-tropical North America (Georgia and Northern Florida, USA).

Number of species: 1.

Taxonomic notes: Several South American taxa described in this genus belong to the genus Simira.

References: P. G. Delprete, Systematics, typification, distribution, and reproductive biology of Pinckneya bracteata (Rubiaceae). Pl. Syst. Evol. 201: 243–261. 1996; P. G. Delprete, Pinckneya, Fl. Neotropica Monogr. 77: 17–18, 29, 41–42. 1999.