Cecropia membranacea Trécul

Species Description

Tree, to 25(-35) m tall. Leafy twigs 2-4 cm thick, usually pale to dark green (to reddish), hispid to (sub)setulose. Lamina chartaceous to subcoriaceous, ca. 40 X 40 cm to 80 X 80 cm, the segments (7-)8-10, the free parts of upper segments obovate, the incisions down to ca. 5/10-7/10; apices acuminate; upper surface smooth, puberulous on the veins and with very sparse arachnoid indumentum or glabrous; lower surface sparsely to densely minutely puberulous, also with longer uncinate hairs or almost glabrous on the veins, the arachnoid indumentum confined to the margin, occasionally present in the areoles; lateral veins in the free part of the midsegment 10-13 pairs, sub-marginally loop-connected, several of them branched; petiole 40-75 cm long, glabrous; trichilia fused, the brown indumentum intermixed with sparse short white hairs; stipules 8-20(-26) cm long, usually green, sometimes dull red, almost glabrous or (very) sparsely hirtellous to hirsute outside, sparsely to rather densely sericeous inside. Staminate inflorescences in pairs, pendulous; peduncle 4-6 cm long puberulous to hirtellous; spathe 8-10 cm long, yellowish, hirtellous outside, glabrous inside; spikes ca. 3040, 7-11(-16) × 0.2 cm, with stipes 0.5-1 cm long and hirtellous; rachis hairy. Staminate flowers: perianth cup-shaped, 0.8 mm long, at the upper part with stiff hairs; filaments swollen; anthers ca. 0.4-0.5 mm long, not appendiculate, remaining attached to the filament at anthesis. Pistillate inflorescences in pairs, pendulous; peduncle 5-15(-20) cm long, hispid, sometimes only just below the spathe; spathe 12-18 cm long, the color and indumentum as in the staminate inflorescence; spikes (2-)4, (7-) 10-16 × 0.4-0.6 cm, to 30 × 1.4 cm in fruit, with stipes 0.5-1 cm long and hirtellous; rachis glabrous. Pistillate flowers: perianth ca. 1.5-2 mm long, with arachnoid indumentum below the apex, also below the aperture inside, the apex slightly convex, minutely and often ± sparsely muriculate; style rather long, straight; stigma penicil-late. Fruit oblongoid, ca. 2.5 mm long, smooth.

Discussion
Cecropia membranacea and C. litoralis are the only lowland species represented both in the Amazon basin and in the Pacific Coastal region. The species is abundant along white-water rivers, as a component of early successional stages on well-aerated soil (cf. Lamotte, 1992). However, it can also be found in flood plain forest, although often in wet places and/ or inundated for short periods, or (less often) far away from rivers. In such places the species is often less ephemeral and can become large trees. The white arachnoid indumentum on the lower surface of the lamina is normally confined to the margin; sometimes some sparse arachnoid is present in the areoles, but it soon disappears. However, in Cuatrecasas et al 26107 from Antioquia (Colombia) the arachnoid indumentum in the areoles appears to be more persistent. Some collections from Ecuador (Cerón 712 and Hurtado et al 2403), erroneously included in C. id-roboi by Berg & Franco Rosselli (1993: 27), and one from Colombia, Putumayo (Franco et al 4679), are distinct by the presence of minute arachnoid indumentum in the areoles of the lamina, which is thicker (coriaceous to subcoriaceous) than normal in C. membranacea. They largely match C. membranacea in other morphological vegetative parts. Collections with staminate inflorescences, which could make affinities clearer, are wanting. The collections examined have not been made from the typical C. membranacea habitat, and they may represent a type with aberrant phenology. They are presently included in C. membranacea with some doubt.

Specimens examined. COLOMBIA. Putumayo: Puerto Asís, on rd. to Kanakas, 6 Feb 1995 ([female] fl-fr), Franco et al. 4679 (BG, COL). ECUADOR. Napo: Reserva Biologica Jatun Sacha, 8 km E of Misahualli, 17 Jan-6 Feb 1987 ([female] fl-fr), Cerón 712 (BG, QCNE), 22 Feb 1990 (st), Céron et al. 8865 (BG); Canton Archidona, rd. Hollín-Loreto, km 65, Huaticocha, 14-19 Jul 1989 ([female] fl-fr), Hurtado et al. 2403 (BG, QCNE).
The incomplete collection from Peru. Loreto, Santa Rosa, nr. Yurimaguas, 11 Nov 1929 ([female] fl), LI. Williams 4949 (F), for which the vernacular name "pungara" is noted, might also belong to this type.
In addition to this type of Cecropia membranacea with arachnoid indumentum on the lower surface of the lamina, two other types have to be mentioned: one indicated as "pungara" in southern Amazonian Peru (Madre de Dios) and the other, which can be indicated as "herrerensis," in northern Amazonian Peru (Loreto); see page 220. The latter is probably represented by Berg et al. 1600, which was not made in a typical C. membranacea habitat and distinct by reddish stipules. With the very scarce and incomplete material available, these two types can hardly or not be distinguished morphologically from typical C. membranacea. They may produce trichilia earlier than normal in the species and they are not inhabited by Azteca ants. The ecology of these types (may) deviates more or less, also with regard to light regimes, and consequently habitat preferences (Davidson & Fisher, 1991). Cecropia membranacea is in cultivation in the Botanical Garden of Universidad Naciónal Agraria, La Molina, Lima (Peru).
Distribution and Ecology: Upper Amazon basin (from Bolivia to Venezuela), the Pacific coastal region of Ecuador and Colombia, extending to eastern Panama, in the lower Río Magdalena valley (Colombia), and the lower Cauca valley (Colombia), common in periodically inundated places along (white-water) rivers, also in non-inundated places, but then often near rivers, at elevations to ca. 1000(-1250) m.

Authority
Berg, Cornelius C. & Franco Rosselli, Pilar. 2005. Cecropia. Fl. Neotrop. Monogr. 94: 1--230. (Published by NYBG Press)