Pleiochiton ebracteatum Triana

  • Family

    Melastomataceae (Magnoliophyta)

  • Scientific Name

    Pleiochiton ebracteatum Triana

  • Primary Citation

    Trans. Linn. Soc. London, Bot. 28: 96. 1871

  • Description

    Description Author and Date: Marcelo Reginato, José Fernando Andrade Baumgratz, and Renato Goldenberg, based on A Taxonomic revision of Pleiochiton (Melastomataceae, Miconieae). Reginato, M., Baumgratz, J.F.A., & Goldenberg, R. Brittonia, 65(1), 2013, pp. 16–41

    Type: Brazil. São Paulo: “In Brasiliae Meridionalis Serra de Cubatão”, W.J. Burchell 3834 (holotype: K).

    Description: Young branches, inflorescences and hypanthia glabrous or sparsely covered by glandular trichomes, 1–1.5 mm long; older branches and leaves glabrous, rarely with eglandular trichomes on acrodromous nerves at the abaxial leaf surface. Old branches 1.5–5 mm diam., nodes 3–9 mm diam. Leaves isophyllous; petioles 2–6(–9) mm long; blade (2–)3.5–7.5 x (0.9–)1.5–4.0 cm, ovate, elliptic or lanceolate, chartaceous or coriaceous, apex shortly acuminate or acute, base rounded, sometimes obtuse or subcordate, margin slightly crenulate and revolute, ciliate (trichomes 0.8–1.1 mm long); acrodromous nerves 3+2, rarely 3 or 5+2, basal, rarely up to 3 mm suprabasal. Cymes 1.5–5 cm long, terminal or lateral, lax, 3–15-flowered, 1–2(–3) pairs of paraclades plus an apical triad, rarely just one triad, anthopodia up to 12 mm long; bracts 1.5–2.5 mm long, ovate to lanceolate, entire, glabrous; bracteoles (1.5–)2–3.5 mm long, not involucral. Flowers (4)5(6)-merous, sessile or pedicels up to 0.4 mm long. Hypanthium 3.5–5.8 x 2.8–4 mm, campanulate or slightly tubular, torus glabrous. Calyx tube 0.4–1.1 mm long, lobes 0.5–1.7 mm long, deltoid; external teeth 3.5–4(–6) mm long. Petals 4.4–6.7 x 2.5–4.5 mm, ovate or oblong, rarely obovate, apex acute or shortly acuminate. Stamens slightly unequal in size, the shorter filaments 2.5–5.5 mm long, the longer ones 4–7 mm long; anthers yellow, dorsally arcuate, the shorter ones 3–4.5 mm long, the longer ones 4–5 mm long, pore dorsal; connective 0–0.5 mm prolonged below the thecae, unappendaged. Ovary (1/10–)1/4–1/3 inferior, 2–3(–3.7) x 1.2–2(–2.7) mm, tubulose or conical, apex glabrous, rarely with sparse eglandular trichomes (0.6–0.7 mm long); style 8–14 mm long. Berries 5.5–8 x 4.5–7.5 mm; seeds 1–1.3 x 0.6–1 mm, 100–150 per fruit.

    Habitat and Distribution: Pleiochiton ebracteatum has the second broadest distribution and is the only endemic one in the southern part of Atlantic Forest, where is sympatric with the widespread P. blepharodes. The species occurs mainly in São Paulo, Paraná and Santa Catarina with a few collections from Rio de Janeiro (not collected since the 19th century) and Espírito Santo (Fig. 3B). Cogniaux (1891) cited Burchell 3834 (the holotype) from Minas Gerais, but the locality mentioned in the label is “Serra de Cubatão”, which is probably in São Paulo. Pleiochiton ebracteatum occurs at medium elevations of Serra do Mar, from 300 to 1000 m, and also on transition zones to Araucaria Forest. The plants were collected near the soil, growing up to 6 m high on the host.

    Phenology: The species has been collected with flowers from January to July, more often from February through April; fruiting material has been gathered from March through August, mainly in July.

    Taxonomy and Systematics: This species is recognized by the inflorescences generally with 1–2 pairs of usually lax paraclades, by the ovate to lanceolate, non-involucral bracteoles, and by the calyx external teeth equaling the hypanthium length. Pleiochiton ebracteatum presents a large variation on the size of leaves, petioles, inflorescences and stamens. Among the species with coriaceous leaves and inflorescences glabrous or sparsely covered by glandular trichomes, P. ebracteatum differs from P. roseum by the smaller and pauciflorous inflorescences, the flowers on anthopodia, and the hypanthium not covered (even partially) by involucral bracteoles. The inflorescences of P. roseum have 2–4 pairs of paraclades and 20-80 flowers, which are in congested triads (anthopodia is inconspicuous), with the hypanthium partially covered by involucral bracteoles. Pleiochiton glaziovianum and P. amorimii are morphologically similar to P. ebracteatum, but they differ from this species by the ratio between the length of the calyx external teeth and the hypanthium, and by the shape of the bracteoles and the calyx inner lobes (see comments under P. amorimii).

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