Rustia viridiflora Delprete
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Authority
Delprete, Piero G. 1999. Rondeletieae (Rubiaceae). Part I. Fl. Neotrop. Monogr. 77: 1-226. (Published by NYBG Press)
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Family
Rubiaceae
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Scientific Name
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Type
Type. Ecuador. Morona-Santiago: Achutza, Jíbaro settlement in the vicinity of Macuma, ca. 50 km N of Macas, 23 Mar 1973 (fl), Lugo 3674 (holotype, GB).
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Description
Species Description - Tree to 20 m tall, to 20 cm at dbh. Leafy branchlets glabrous to minutely puberulent, terete; older branches glabrate, rugulose, grayish to pale brown; lenticels sparse, punctiform to linear, to 1 cm long. Stipules not seen (readily caducous), leaving a linear scar 1-1.5 mm wide, of the same color of stem. Leaves 38-69 × 9.5-20.5 cm, L/W 3:1 to 3.5:1; lanceolate to elliptic, acute to obtuse (35-65°) at base, acute to attenuate at apex, sometimes tapering to an acumen 2-3 cm long; blade dark green above, dull green below, stiff-foliaceous; drying pale brown, stiff-chartaceous; glabrous above and below, pellucid punctate; primary and secondary veins glabrous, prominent below; secondary veins 19-25 each side; tertiary veins starting subparallel and openly reticulate in the center, faintly evident above, fairly evident below; petioles 4.5-7 cm long, 3-5 mm thick, subterete, glabrous; basally thickened but not pulvinate; domatia absent. Inflorescences laxly paniculate, pyramidal, with decussate racemoid lateral branches; 22-54 × 9-22 cm, lateral branches 3-7 pairs, basal portion of axis not branched 10-20 cm long; rachis terete to decussately obtuse-compressed, rachis and branches glabrous to minutely puberulent; flowers on distal racemoid branches or on racemoid-cymules; bracts subtending lateral branches 1-3 × 2-3 mm, deltoid; bracteoles subtending flowers 0.5-1 × 0.7-1 mm, deltoid, glabrous. Flowers pedicellate, pedicels 6-9 mm long, glabrous to minutely puberulent; hypanthium narrowly obconical, 46 x 2-4 mm, glabrous to minutely golden-hirtellous; flower buds cylindrical. Calyx reduced to a wavy margin with barely distinguishable lobes, 0.3-0.5 mm long. Corolla tubular with bulbous base and small constriction just above, 1.9-2.2 cm long, green throughout (rarely reddish with green lobes), semifleshy when fresh; tube subcylindrical, striate, 1.4-1.8 cm long, 4-5 mm wide at base and 2-2.5 mm wide at the orifice, glabrous or golden-hirtellous outside; antrorse-strigose at base inside, without a ring of hairs, the remaining medial and superior zones glabrous or with sparse hairs; lobes 5, 1/4-1/5 of corolla length, 3-5 × ca. 2.5 mm, triangular to ovate, glabrous outside, glabrous, with minute glandular hairs (hairs to 0.5 mm long) at margins inside. Stamens 5, included (only the very tip exserted), subequal, attached 3.5-5.5 mm from the base of the tube; filaments 6-7 mm long, sparsely ascending-pilose, with a tuft of golden-pilose hairs at base; anthers elongated, rectilinear (never convex), 11-12 × 1.2-1.3 mm, dorsifixed near base, base subcaudate, with sharp ridges, papillose-echinate to ascending-strigulose, descending glandular-pilose at base. Pollen exine densely foveolate, sparsely minutely echinate. Style exserted, 22-28 mm long, glabrous and minutely verrucose throughout; style branches ovate, acute at apex, 1-1.3 mm long, stigmatic surface smooth to minutely papillose; immature fruits green to reddish. Capsules very narrowly obconical, apex conical, (14-) 18-23 × 4-6 mm, black, without lenticels, glabrous throughout; disk septicidal dehiscence absent even in old capsules. Seeds 0.871.27 x 0.33-0.83 mm.
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Discussion
Rustia viridiflora is unique in the genus in its long narrowly obconical capsules with conical disk, corollas basally bulbose, and long rectilinear anthers. Its corollas are commonly entirely green (rarely red tube with green lobes). This is one of the four species of Rustia with pendulous flowers (Delprete, 1996a), all of which have long-narrow corollas and occur in western South America. A key to the pendulous-flowered species of Rustia was published by Delprete (1996a).
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Distribution
Primary and disturbed forests, from low to medium elevations, (300-)800-1200 m, of S Amazonian Ecuador. Flowering specimens were collected in March, October, and November. Fruiting specimens were collected in March and November. Its pollination biology has not been studied, but its flowers are likely to be pollinated by hummingbirds.
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