Rubiaceae of the New World

By Piero Delprete and Rocio Cortés

ISIDOREA A. Richard in de Candolle

Isidorea pungens 
Flowers and young fruits (upper left)
National Botanical Garden (cultivated)
Santo Domingo, Dominican Republic

Isidorea cf. leonardi
Habit (upper right)
Habitat (lower left)
Mun. Duverge, Prov. Independencia
Dominican Republic

Photos P. Delprete

Shrubs; raphides absent; axillary thorns absent. Stipules interpetiolar, free at base or interpetiolar, connate at base, triangular and aristate, subcaducous. Leaves opposite, short-petiolate, subsessil or sessil; blades broadly ovate, narrowly elliptic, elliptic, broadly obovate or oblanceolate, stiffly coriaceous, pungent at apex; foliar pellucid glands absent; domatia absent. Inflorescence axillary, cymose, pauciflorous or uniflorous. Flowers bisexual, protandrous. Calyx tube absent, lobes connate at base or tube absent, lobes free at base, persistent; lobes 4 to 6, linear, small. Calycophylls absent. Corolla tubular or narrowly infundibuliform, actinomorphic, white to cream-white, reddish-white, pink, red, reddish-brown, violet to purple; tube externally glabrous, internally glabrous, without a pubescent ring inside; orifice annular thickening absent; lobes 4 to 6, imbricate (tube reduplicate), broadly triangular; margin entire, rounded at apex. Stamens alternate to the corolla lobes, partially exserted (only tips exserted); anthers elongate, tecae 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, obconical or turbinate; 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, minute or medium-sized, 3-5-angular or elliptic, narrowly elliptic, ovate to obovate in outline; wings absent.

Geographic distribution: West Indies.

Number of species: 17.

References: P. C. Standley, Isidorea, N. Am. Fl. 32(1): 1415. 1918; A. Aiello, A reexamination of Portlandia (Rubiaceae) and associated taxa. J. Arnold Arb. 60: 38123. 1979; A. H. Liogier, Isidorea, Fl. Española 7: 311318. 1995.