Monographs Details – French Guianan E-Flora Project

Monographs Details:

Authority:

Pennington, Terence D. 1981. Meliaceae. Fl. Neotrop. Monogr. 28: 1-359, 418-449, 459-470. (Published by NYBG Press)

Family:

Meliaceae

Scientific Name:

Guarea silvatica C.DC.

Synonyms:

Guarea pedicellata C.DC., Guarea duckei C.DC., Guarea bilocularis C.DC., Trichilia longeracemosa Glaz., Guarea klugei Harms, Guarea filiformis C.DC.

Description:

Species Description - Young branches glabrous (young leaf buds with sparse minute puberulous indumentum), greyish-green, smooth, becoming pale brown, sometimes with longitudinal lenticels and often scaling in thin irregular pieces to reveal a green undersurface. Leaves paripinnate without a terminal bud, (8-)12-30(-50) cm long; petiole and rhachis ± terete, glabrous; petiolule (l-)3-4(-7) mm long. Leaflets 2-4(-6) pairs, usually elliptic, less frequently lanceolate, oblanceolate or oblong-elliptic, apex short to long acuminate, base narrowly attenuate or acute, less frequently cuneate, chartaceous to subcoriaceous, (6.5-)10-20(-32)[15.0] cm long, (2.5-)4-8(-13)[5.7] cm broad, glabrous, not glandular-punctate or -striate; venation usually eucamptodromous less frequently brochidodromous, midrib slightly prominent; secondaries 6-10(-ll) on either side of midrib, arcuate, ascending, usually convergent; intersecondaries often long; tertiaries forming a prominent reticulum. Inflorescence axillary or sometimes several on a short lateral shoot, 8-40(-125) cm long, nearly always unbranched, flowers clustered along axis in distant cymose fascicles or rarely subracemose, minutely puberulous or glabrous; pedicel 2-4 mm long. Flowers ?bisexual. Calyx rotate, patelliform or cyathiform, 0.5-l(-2.5) mm long, margin entire or with 4 rounded to acute lobes 0.5-1 mm long, glabrous or sometimes slightly ciliate. Petals 4(-5), imbricate or very rarely contorted, 5-7.5(-10) mm long, 1-3 mm broad, broadly oblong to strap-shaped, apex rounded to acute, usually glabrous or occasionally papillose at apex on inner surface. Staminal tube (4-)5-6(-8.5) mm long, 1.5-3 mm broad, margin entire, undulate or shallowly lobed, glabrous; anthers (5-)8(-10), 0.5-0.75 mm long. Nectary a stout stipe expanded to form a collar beneath ovary, 1-2 mm long, glabrous. Ovary ovoid, 2-3(-4)-locular, loculi with 1-2 superposed ovules, glabrous; style stout, glabrous. Capsule testiculate, constricted between the seeds, smooth, glabrous, 3.8-5.0 cm long, 2.5-4 cm broad, 2(-3)-valved, valves 1-seeded; pericarp 1.5-2 mm thick. Seed ovoid to ellipsoid, 2.7-3 cm long, 1.82 cm broad, surrounded by a thin fleshy orange sarcotesta; hilum large, ca. 1.82 cm long, 0.9 cm broad; seed coat bony, ca. 1 mm thick. Embryo with thick plano-convex, collateral cotyledons; radicle apical, minute, extending to surface.

Discussion:

Relationships

Guarea silvatica is a most distinct species, easily recognized by the glabrous, paripinnate leaves lacking the terminal bud, the long unbranched inflorescence bearing distant fasciculate cymules of glabrous flowers, the imbricate corolla, the large, glabrous, thin-walled fruit, constricted between the valves, the large seeds with a bony seed coat and embryo with collateral cotyledons. It is without any close relatives and the only species which bears it any resemblance is G. pterorhachis, which shares some of its floral and fruit characters.

This species is apparently hermaphrodite as all flowers are morphologically similar and capable of setting fruit (both terminal and laterals on each cymule).

However, it is clear from field observations that some trees are functionally male, never setting fruit, while others always set fruit.

Field characters: Tree to 20 m but frequently flowering when 1 m or less. The bark is smooth, greyish-green in young specimens becoming dark grey and scaling in thin, narrow, longitudinal pieces in older trees. The scentless cream-coloured flowers are borne on a pendulous inflorescence which may be up to 1 m long. The dehiscent fruit has a rather thin leathery, brown or reddish-brown pericarp and contains seeds with an orange sarcotesta. The flowering season is from August to January. The fruit matures over a long period with records from February, April-May, and July.

Distribution and Ecology: From Peruvian Amazonia across western and central Amazonia to Guyana and the states of Para and Maranhão, Brazil. There is one very doubtful record from the Atlantic coastal forests of Brazil (Glaziou 9712, Espirito Santo, Serra de Itabapuana). The species is a component of undisturbed lowland rain forest where it is a small to medium-sized tree. However, it is also common in secondary forest. Its ability to form sucker shoots enables it to persist in cut-over forest where it may be seen flowering when only 1-2 m high. The hard seed coat protects the embryo from predators and the seed can lie on the forest floor for several months without losing its viability.