Monographs Details: Chimarrhis gentryana Delprete
Authority: Delprete, Piero G. 1999. Rondeletieae (Rubiaceae). Part I. Fl. Neotrop. Monogr. 77: 1-226. (Published by NYBG Press)
Family:Rubiaceae
Description:Species Description - Trees usually 15-20 m tall, exceptionally to 30 m tall; bark deeply fissured, fibrous; wood extremely hard. Leafy branchlets 4-8 mm thick, semi-succulent, terete to subterete, glabrous; older branches smooth (not exfoliating in narrow strips), grayish pale brown; lenticels not found. Stipules connate at base, not contorted in bud, often adnate to petioles, deltoid, not acuminate, glabrous outside, microscopically (40×) ciliolate, glabrous with a basal triangular area of colleters inside, 8.5-9 × 6.5-10 mm, reddish green, subcaducous, leaving a scar encircling the stem and connected to the petiole scars, 1-2 mm wide. Leaves (8-) 13-24 × (4-)8-13 cm, L/W = 1.5:1 to 1.7:1, pandurate, obtuse to rounded at base, concave at basal area, obtuse at apex, acumen absent; dark green above, pale green below, semi-coriaceous; drying reddish brown, semi-leathery to leathery; glabrous above and below; primary and secondary veins glabrous, prominent below, secondary veins 7-10 each side; tertiary veins subparallel throughout; petioles 6-12 mm long, 2-3 mm thick, terete to adaxially flattened or narrowly concave, glabrous; domatia absent. Inflorescences 2 per node, corymbose, densely branched distally, with opposite to subopposite decussate branches terminating in cymules, forming a continuous flowering plane, 9.5-15 × 7.5-11 cm, lateral branches 1-2 pairs, basal portion of axis not branched 4.5-7.5 cm long; L/A = 1.5 to 2:1; rachis basally subterete, distally decussately compressed, rachis and branches white or golden minute-puberulent; distal bracts absent or extremely reduced, deltoid to linear, to 4 × l mm; bracteoles subtending flowers absent or reduced to microscopic scales. Flowers sessile to short-pedicellate; pedicels to 1.5 mm long, puberulent; hypanthium narrowly obconical, 1-1.5 × ca. 1 mm, puberulent. Calyx extremely reduced, truncate to short-lobed, 0.4-0.8 × 1.3-2 mm, golden puberulent, pale green; lobes barely distinguishable, to 0.5 mm long; in some flowers one calyx lobe expanded into a calycophyll. Calycophylls 5-7 × 1.6-3 cm, blades ovate to elliptic, with peltate venation, pale green to white; stalks 1.5-2 cm long. Corolla funnelform, deeply lobed, the lobes reflexed at anthesis, 3.5-4.5 mm long, white to greenish white; tube short cylindrical, 1.5-2.5 × 0.5-0.7 mm, glabrous outside and inside; lobes 5, 2-2.5 × 0.6-0.8 mm, narrowly oblong with acute apex, glabrous outside, with a basal area white-pilose and with distal zone glabrous inside. Stamens 5, exserted well above the corolla, equal, attached 1-2 mm from the base of the tube; filaments 3.5-5 mm long, terete, basally flattened, connate to throat, sparsely white pilose at base; anthers elliptic, 0.6-0.7 × 0.3-0.5 mm, medially dorsifixed, base rounded, apex acute to short mucronate. Pollen not seen. Style exserted, 5-6 mm long, terete, densely strigose, appressed-retrorse; style branches extruding as two lips above corolla before anthesis, oblate, 0.3-0.6 mm long, stigmatic surface microscopically (40×) papillose; ovary-galls present. Capsules narrowly obconical to turbinate, acute at base, rounded at apex, 3.5-5 × 1.5-3.5 mm, rust-brown, without lenticels, densely golden puberulent below the disk; disk white-pubescent, not exceeding the calyx; disk loculicidal dehiscence present in old capsules. Seeds 0.95-1.13 × 0.58-0.88 mm.

Discussion:This species is easily recognizable by its numerous cream-white calycophylls (Fig. 81 A), rust-brown puberulent capsules, and puberulent disk which does not exceed the calyx. The calycophylls usually darken and break off at capsule maturity. The leaf blades of C. gentryana are commonly pandurate, semi-leathery, and olive-green when fresh, turning reddish brown when dry.

Chimarrhis gentryana is most similar to C. brevipes (of the Venezuelan Amazon), both possessing pandurate leaves and calycophylls; the former differs from the latter in having narrowly obconical capsules (vs. broadly obovoid), which are rust-brown (vs. beige-brown) and densely golden-puberulent (vs. sparsely white-puberulent).

Chimarrhis gentryana is often confused with Calycophyllum obovatum (Ducke) Ducke, because of its white calycophylls, minute white flowers, and obovate to pandurate leaves (Fig. 81A-E). The genus Calycophyllum differs from Chimarrhis in having terminal inflorescences (vs. axillary and subterminal), seeds with strongly bipolar wings (vs. minute seeds with small concentric wing), and smooth thin bark exfoliating into long vertical strips (vs. soft-fibrose bark falling off in small irregular pieces).

Chimarrhis gentryana is commonly encountered as medium-sized trees (15-20 m tall; but two emergent individuals were reported to be 25 and 30 m tall), growing below the high canopy Amazon forest (3035 m high), with small buttresses, rust-brown fibrous bark, leathery leaves, cream-white fragrant flowers, and cream-white calycophylls.
Distribution:Ecuador South America| Pastaza Ecuador South America| Peru South America| Amazonas Peru South America| Loreto Peru South America| Brazil South America| Amazonas Brazil South America|