Rhabdodendron macrophyllum (Spruce ex Benth.) Huber
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Authority
Prance, Ghillean T. 1972. Rhabdodendraceae. Fl. Neotrop. Monogr. 11: 1-22. (Published by NYBG Press)
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Family
Rhabdodendraceae
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Scientific Name
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Type
TYPE. Spruce 1408, Dec - Mar 1850-51, s k in some sets), Brazil, Amazonas, Manaus, fl (holotype, K; isotypes, CGE, F, LD, NY, OXF, P).
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Synonyms
Lecostemon macrophyllum Benth., Rhabdodendron columnare Gilg & Pilg.
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Description
Description - Shrub to 6.0 m tall with numerous thin trunks arising from below ground, the young branches glabrous, with a thin hard bark, the wood without secondary phloem. Leaves oblanceolate, lanceolate or obovate-oblong, gradually narrowing from above middle to base, with much variation in size and shape within the same individual, chartaceous, (7.0-)9.0-32.0(-38.0) cm long, (1.5-)2.0-7.5(-8.6) cm broad, the apex rounded, acute or minutely acuminate or mucronate, gradually narrowed to a cuneate base, glabrous above, with scattered peltate hairs beneath, not rugose on surfaces; midrib plane to prominulous above, prominent beneath; primary veins 25-40 pairs, prominulous on both surfaces, arcuate and anastomosing 1.0-6.0 mm from margin and forming a prominulous marginal nerve; petioles 2.0-6.0 mm long, glabrous, usually minutely winged and shallowly canaliculate. Stipules small, subulate. Inflorescences of axillary racemes 3.0-9.0 cm long, with sparse peltate pubescence. Bracts and bracteoles ovate, persistent, 0.5-1.0 mm long, membraneous, glabrous; pedicles 5.0-12.0 mm long, glabrous and frequently with up to 3 small bracteoles. Calyx-tube turbinate-campanulate, ca 3.0 mm long, the lobes represented by 5 obscure teeth only, the exterior glabrous. Petals 5, oblong. 6.0-8.0 mm long, membraneous, glabrous; pedicels 5.0-12.0 mm long, glabrous and frequently with up to 3 small bracteoles. Calyx-tube turbinate-campanulate, ca 3.0 mm long, the basifixed, caducous. Ovary globose, glabrous. Style arising from base of ovary to one side of it, elongate, the stigmatic surface long and linear. Fruit subglobose, 5.0-6.0 mm diameter; exocarp glabrous, smooth, but wrinkled when dry; mesocarp very thin, fleshy; endocarp thin, bony, fragile, with median line of fracture, glabrous within. Germination hypogeal, first leaves alternate, minute, 2.0-5.0 mm long, with a single long tap root.
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Discussion
Rhabdodendron macrophyllum is closest to R. amazonicum but differs in the leaf shape, the strongly anastomosing primary veins which form a marginal nerve, the shorter petioles, and in the absence of anomalous secondary phloem in the wood. This species is extremely polymorphic in leaf shape and size, even within the same individual. I have observed and collected it several times around Manaus and Prance 2080 is a series showing the range of leaf shape on the same bush, varying from narrowly lanceolate leaves 9.0 X 1.5 cm to oblong leaves 25.0 X 8.0 cm.
Collected in flower around the year but more in December to June.
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Distribution
Characteristic of and common in sandy savannas and secondary savanna in the lower Rio Negro region of Amazonian Brazil and eastward to western Para.
Brazil South America| Amazonas Brazil South America| Pará Brazil South America|