Panicum harleyi Salariato, Morrone & Zuloaga

L. Salariato, Diego & O. Zuloaga, Fernando, 2011, New Species of Paniceae (Poaceae, Panicoideae) from Brazil, Systematic Botany (Basel, Switzerland) 36 (1), pp. 53-58 : 55-56

Panicum harleyi Salariato, Morrone & Zuloaga , sp. nov.

— TYPE: BRAZIL. Bahia. Rio de Contas , ca. 5 km da cidade, em direção ao Pico das Almas , 13°32 ' 58 " S, 41°51 ' 03 " W, 1,107 m, 1 Aug 2006, R. M. Harley 55486 (holotype: HUEFS!) .

Panicum condensato affine sed laminis cordatis et pseudopetiolatis, amplexicaulibus, inflorescentiis ca. 50 ramos, et palea inferiore absens differt.

Plants of indefinite duration, probably perennial. Culms decumbent, rooting at the lower nodes, then becoming erect, ca. 50 cm tall; internodes 3–7 cm long, compressed, hollow, glabrous; nodes dark, compressed, glabrous. Sheaths 2–7 cm long, usually shorter than the internodes, striate, glabrous, the margins membranous, pilose. Ligules 0.7 mm long, membranous, with a short and sparse fringe of hairs at the apex; collar brown, glabrous. Blades 7–13 × 0.3–0.6 cm, lanceolate, sparsely pilose on the adaxial surface, the abaxial surface glabrous, subcordate, the apex acuminate, margins membranous, ciliate at the base, otherwise glabrous. Peduncles ca. 11 cm long, exserted, terete, glabrous. Inflorescence an open terminal panicle 15 × 7 cm; main axis wavy, smooth, glabrous on the lower portion, otherwise hispid; pulvini glabrous or sparingly pilose; first order branches 11, alternate and divergent, distant 1–4.5 cm from each other, the lower ones 4.5–5.5 cm long, second order branches basal in the first order branches, short, with 3–4 spikelets; axis of the branches triquetrous, glabrous, scabrous, purple; spikelets paired and unilaterally arranged; pedicels 1–5 mm long, claviform, glabrous to finely scabrous toward the apex, purple. Spikelets 2.5–2.6 × 0.8–1 mm, ellipsoid, green and tinged with purple, glumes and lower lemma membranous, with small papillae all over its surface, the upper glume and lower lemma subequal. Lower glume 1.5–1.7 mm long, ca. 2/3 the length of the spikelet, acute, 3–5-nerved, the midnerve scabrous. Upper glume as long as the spikelet, acute, 5-nerved, the midnerve scabrous. Lower lemma glumiform, 5-nerved, the midnerve scabrous. Lower palea small, hyaline, glabrous; lower flower absent. Upper anthecium 2.3–2.5 × 0.6–0.7 mm, long-ellipsoid, pale, membranous, with simple papillae regularly distributed all over its surface and prickles toward the apex of lemma and palea, the apex cucullate ( Fig. 5 ); upper lemma 5-nerved; lodicules ca. 0.3 mm long, 2, cuneate; stamens 3, anthers 1.4 mm long. Caryopsis 1.1 × 0.6 mm, ovoid; hilum elliptical, embryo less than half the length of the caryopsis. Figure 4 .

Etymology— The new species is named in honor of Dr. Raymond M. Harley , a renowned botanist and a great collector of the Brazilian Flora.

Distribution and Habitat— Only known from Rio de Contas in Bahia, Brazil, where this rare species grows in “brejos,” or swamp, humid areas at an elevation of 1,100 m.

Observations— Panicum harleyi belongs to Panicum sect. Laxa ( Zuloaga et al. 1992) ; it has spikelets unilaterally arranged on the branches, the upper glume and lower lemma 5-nerved, and the upper anthecium membranous, with simple papillae and prickles. Within this section, P. harleyi is morphologically similar to P. condensatum , from which the latter differs by having cordate, pseudopetiolate, and amplexicaulous leaves, inflorescences with nearly 50 branches, and lack lower paleas. As with other species of P. sect. Laxa , P. harleyi is a C 3 species with several cells between consecutive vascular bundles, and with associated fusoid cells ( Fig. 3 , C-D).

Figures

FIG. 5. Micromorphology of the upper anthecium of P. harleyi (Harley 55486). A. Upper anthecium, dorsal view. B. Ornamentation of the upper lemma surface showing simple papillae.C. Apex of the upper lemma, dor- sal view. D. Detail of apex of the upper anthecium showing prickles and tetralobed silica bodies. Scales: A = 500 µm, B and D = 20 µm, C = 50 µm.

FIG. 4. Panicum harleyi. A. Habit. B. Detail of ligule. C. Spikelet, lateral view. D. Spikelet, ventral view. E. Spikelet, dorsal view. F. Lower palea. G. Upper anthecium, dorsal view. H. Upper anthecium, ventral view. I. Upper lemma. J. Lodicules. K. Caryopsis, embryo view. L. Caryopsis, hilum view (based on Harley 55486).

FIG3. Leaf blade anatomy of D. barbadense and P. harleyi. A-B. Dichanthelium barbadense (Giulietti et al. 1454). A. Transverse section of the blade. B. Detail of vascular bundles, showing extensions of the outer sheath with arrows. C-D. Panicum harleyi (Harley 55486). C. Transverse section of the blade of B. Detail of a second order vascular bundle, showing fusoid cells with arrows. Scales: A,B,C = 100 µm, D = 50 µm.