Trichilia laxipaniculata Cuatrec., Fieldiana, Bot.

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 116-117

58. Trichilia laxipaniculata Cuatrec., Fieldiana, Bot. 27(1): 82 (1950); T. D.Penn., Fl. Neotrop. 28: 146 (1981). Type:— ECUADOR. Rio San Miguel o Sucumbios, fl., Cuatrecasas 10942 (holotype, F; isotypes, A, US). Map 66

Young branches stout, 1–2 cm diam., hollow, at first minutely and sparsely appressed puberulous, soon glabrous, smooth, pale to dark brown, with pale lenticels. Bud scales absent. Leaves pinnate with one of the terminal pair orientated to simulate a terminal leaflet, petiole 6–11 cm long, strongly channelled and winged towards the base, glabrous, rhachis 24–36 cm long, semiterete or 3-angled, glabrous; petiolule 3–10 mm long, glabrous. Leaflets mostly alternate, rarely subopposite, 12–13, uppermost 12 × 4.5–35 × 12 cm, elliptic, oblanceolate, or broadly oblong, apex obtusely cuspidate to acuminate, base acute to rounded, subcoriaceous, glabrous, obscurely glandular-punctate and -striate; basal pair of leaflets usually greatly reduced, 4 × 2–5 × 2.5 cm, ovate or broadly elliptic, apex obtuse or rounded; venation eucamptodromous, midrib flat (not raised or sunken) on the upper surface, secondaries 18–23 pairs, ascending, straight or slightly arcuate, parallel or slightly convergent; intersecondaries usually absent; tertiaries obscure, oblique. Inflorescence axillary, 25–55 cm long, peduncle 14–35 cm long, a widely branched, many-flowered panicle, longest lateral branches 10–20 cm long, minutely puberulous to subglabrous; pedicel ca. 1 mm long (above the articulation). Flowers?unisexual (probably dioecious, male flowers only seen). Calyx 0.25–0.5 mm long, rotate to patelliform, margin shallowly 5-lobed, lobes broadly ovate, obtuse, with sparse appressed hairs outside. Petals (4–)5, 1.75–2 mm long, fused for ca. 1/2 their length, lobes valvate, erect, ovate to triangular, apex acute, sparsely appressed puberulous outside, glabrous inside. Staminal tube ca. 1.5 mm long, cup-shaped, filaments completely fused, margin with 5–6 subulate teeth, equalling or slightly exceeding the anthers, glabrous; anthers 5–6(–8), 0.5–0.75 mm long, ellipsoid, glabrous. Nectary absent. Ovary ca. 0.75 mm long, conical or broadly ovoid, 3-locular, locules with 2 collateral ovules, appressed puberulous; style-head small, capitate, held below the anthers. Capsule 2–3.5 cm long, 1.3–2.2 cm broad, 3-valved, obovoid, with an apical beak (at least when dry), smooth or rarely strongly tuberculate, glabrous, drying dark brown; pericarp ca. 0.75 mm thick. Seeds 1–3, 1.2 x 1–1.9 x 1.4 cm, obovoid, apex rounded or truncate, base acute, seed coat membraneous, with a fleshy arillode which extends from apex to base and covers ca. one third of the seed surface and is prolonged at the apex into a beak 0.5–1 cm long. Embryo with plano-convex, collateral cotyledons, radicle included, towards the apex; endosperm absent.

Field Characters. Tree to 30 m high and 50 cm diam., with slightly fissured bark. The flowers are pale greenish-cream, and the mature fruit green. Both twigs and young fruit produce pale cream-coloured exudate when cut. Flowering is recorded from September to November and mature fruit from December to February.

Distribution & Ecology. Amazonian Ecuador and Peru to central Amazonian Brazil, not yet recorded from Colombia but to be expected there. A component of lowland evergreen rain forest, on a variety of soils, including non-flooded red soils, alluvial terraces and on periodically flooded sites, up to 400 m elevation.

Additional Collections Examined. ECUADOR. Napo: Reserva Biológica Jatun Sacha (SW0177), Cerón 2583 (K, NY), Cerón & Montesdeoca 8116 (NY), Cerón et al. 5371 (K), Neill & Manning 8003 (NY), Palacios 2485 (K, MO); Cantón Archidona, Avila Nueva, base of Volcán Sumaco (SW0077), Hurtado 2602 (K); Rio Napo, 8 km below Puerto Misahualli (SW0177), Neill & Palacios 7099 (K); Cantón Loreto, Tiyuyacu community (SW0077), Neill et al. 12419 (F, MO); Loreto, 2.5 km N of road to Campo Alegre (SW0077), Vargas & Cerda 647 (K, MO). Orellana: Huaorani Ethnic Reserve, Maxus road km 116 (SW0176), M. Aulestia 3373 (K); La Joya de los Sachas, Pompeya (SW0076), Grijalva et al. 227 (NY); Cantón de los Monos, 15 km N of Coca (SW0077), Neill 7140 (NY); 30 km NNW of Coca, R. Huashito (SW0077), Pennington 10624 (K, QCNE); El Chuncho Reserve, INIAP-Coca (SW0077), Palacios 3157 (MO); INIAP Station, San Carlos (SW0076), Palacios et al. 1018 (M)), Añangu, Yasuní National Park (SW0076), SEF 8537 (K), 8912 (K), 9027 (K), 10255 (K), 10259 (K), 10525 (K). Pastaza: Cantón Pastaza, Pozo petrolero “Namoyacu” (SW0176), Espinoza & Coba 586 (K). Sucumbios: Cantón Lago Agrio, Dureno (SW0076), Cerón & Cerón 3157 (K); Shushufindi, San Isla (SW0076), Freire & Suarez 5076 (K); Cantón Lago Agrio, Cuyabeno Reserve, Laguna Grande (SW0076), Palacios et al. 9343 (K).

MAP 66. Distribution of Trichilia laxipaniculata Cuatrec. Solid dots, distribution pre-1981, open dots new records 1981–2010.

PERU. Loreto: Prov. Ucayali, Canchahuayo (SW0775), Vásquez et al. 6938 (MO, NY); Maynas Prov., Iquitos- Nauta, km 44 (SW0473), Vásquez & Jaramillo 11469 (MO). San Martín: Tocache Nuevo, R. Huallaga, Fundo San Rafael (SW0876), Schunke 4423 (K, MO).

BRAZIL. Acre: Municipio Marechal Thaumaturgo, R. Tejo (SW0972), Daly et al. 10425 (K). Amazonas: Reserva Florestal Ducke (SW0259), Souza & Assuncão 469 (K).

Relationships. Floral structure close to that of T. tuberculata , but differing in the hollow twigs, winged petiole, and much larger leaves and inflorescence. The flowers are similar, but the petals remain erect in T. laxipaniculata (spreading and reflexing in T. tuberculata ). The morphological similarity is supported by their placement in the ITS analysis.