Melochia L.
Contenido
Descripción
Mostly shrubs or subshrubs, sometimes herbs or small trees, 0.08- 15.0 (-20) meters high, mostly perennial, often with a woody taproot, sometimes 2-5 times thicker than the base of the stem and 0.4-2.2 cm. wide, the young stems subglabrous to cinereous or canescent, hirsute, pilose, sericeous, or tomentulose, hairs stellate, simple, forked or glandular, sometimes tan, golden, or ferruginous, 0.06-4.0 mm. long, the internodes 0.2-18.5 cm. long; leaves simple, alternate; stipules 1.5-10.3 mm. long, 0.2-4.0 (-12) mm. wide, deltoid-acuminate or deltoid-acute, generally lanceolate or linear, sometimes ovate or suborbicular, usually ciliate and hirsute, tomentulose or sericeous, hairs simple, stellate, forked or glandular, 0.05-3.5 mm. long; petiole 0.07-14,5 (-20.5) cm. long; lamina 0.6-24 (-30) cm. long, 0.2-21.5 (-27) cm, wide, ovate, lanceolate, linear, oblong-ovate, suborbicular, or elliptic, one side sometimes larger than the other, the base usually rounded to cordate, sometimes truncate, cuneate or oblique, the apex usually acute to acuminate, sometimes rounded, both surfaces glabrous, hirsute, sericeous or tomentulose and canescent or cinereous or brownish, sometimes velutinous or lanate, hairs stellate, simple, forked, or a combination of these, sometimes also glandular, 0.05-4.0 mm. long, rarely covered with resin-colored granules or pulverulent, the margin usually irregularly crenate-serrate, serrations 0.3-12.0 mm, wide, 0.2-3.6 mm. high, 4-15 pairs of primary veins, usually 2 being basal, usually impressed above and prominent beneath.
Inflorescences axillary, terminal, leaf-opposed, or 90° from the leaf, umbellate, subcapitate, paniculate, spicate or corymbiform, cymose, 0.6-34 cm. long, the peduncle 0-11 (-16) cm. long, sometimes with a primary branch 0.2-5.2 (-7.0) cm. long, a secondary one up to 2.0 (-4.0) cm. long, a tertiary one up to 1.6 (-3.0) cm. long, and rarely a quaternary one up to 2 cm. long, the pedicel 0-14 (-19) mm. long; bracts 0.5-12.2 mm. long, 0.1-3.9 (-14) mm. wide, sometimes 2-3 immediately subtending each flower, at other times at the base of the pedicel, sometimes 2-3 united part way; flowers: few to numerous, fertile stamens 5, antepetalous, staminodes usually absent, sometimes 5, alternate with the stamens, 0.1-1.2 mm. long, usually dentiform, sometimes elongated, the anthers 0.4-2.6 mm. long, 0.3-1.4 mm. wide, oblong, emarginate at both ends, sometimes nearly to the middle from the apex, the carpels 5, rarely 6-8, antepetalous, styles filiform, sometimes slightly clavate at the apex, ovules 2 per carpel.
Calyx quinquefid, valvate in aestivation, persistent, usually green, sometimes rose, rose purple, yellow, orange, red, or pinkish brown, sometimes canescent, sometimes membranous, 1.4-15.0 mm. long, 2.1-10 mm. wide, the teeth 0.4-7.8 mm. long and 0.2-4.8 (-5.5) mm. wide, sometimes accrescent, becoming up to 36 mm. long and 19 mm. wide, with teeth up to 12 mm. long and 10 mm. wide, the teeth usually deltoid-acute or deltoid-acuminate, sometimes ovate or nearly linear, hirsute, tomentulose, or sericeous, sometimes ciliate, hairs simple, stellate, glandular, or forked, 0.05-2.3 (-4.0) mm. long, the sinus usually acute, sometimes rounded to truncate; petals purple, pink, purple distally and yellow or orange proximally, yellow, orange, white, blue, red, white with red stripes, or violet, 2.7-17.4 mm. long, 0.8-9.5 mm. wide, usually obovate or oblanceolate, sometimes obdeltoid, obovate-oblong, elliptic, oval, ovate or oblong, cuneate or spatulate, free of the staminal tube or attached to it for 0.3-5.0 mm., the claw 0-6.5 mm. long, rarely glandular tissue present between the calyx and corolla, with lobes extending between the bases of the petals, sometimes a few glandular, simple, forked, or stellate hairs on the petals. Longistylous form. Stamens 2.4-7.0 (-9.0) mm. long, the filaments united up to the anthers or free for 0.2-3.0 mm., sometimes a few hairs at the base of the staminal tube; pistil 2.6-10.9 (-12) mm. long, the styles free for 1.2-6.7 mm., to the ovary or united for 0.3-4.0 mm., papillose at the apex for 0.5-2.5 mm. Brevistylous form. Stamens 2.8-11.3 mm. long, sometimes with a few hairs at the base of the staminal tube, the filaments free for 0.5-7.5 mm.; pistil 2.3-6.9 (-8.0) mm. long, the styles free for 0.8-5.3 mm, to the ovary or united for 0.2-3.0 mm., papillose for 0.3-1.0 mm. at the apex.
The flowers of several species in the section Melochia not dimorphic, stamens and pistils 1.7-3.2 mm. long, the filaments free for 0-1.2 mm., the styles free for 0.6-1.2 mm., to the ovary or united for 0.1-0.3 mm.
Fruit schizocarp or capsule, 2.4-10,5 (-12) mm. long, 2.9-17.0 (-22) mm. wide, subglobular and pentagonal, pyramidal and pentapterous, ovoid or oblong, the sulci between the carpels shallow to deep, extending a fifth to half way to the center of the fruit, usually hirsute, tomentulose, or sericeous, subglabrous to canescent, hairs stellate or simple, sometimes also forked or glandular, 0.1-1.6 mm. long, the stipe 0-6.7 mm. long; dehiscence septicidal, loculicidal, or both; seeds brown to black, 1 or 2 per cell, 1.4-3.9 mm. long, 0.9-2.5 mm. wide, usually trigonal, the dorsal surface rounded and the sides flat, sometimes obovate, sometimes somewhat flattened, in one section the seed may have an ascending membranous wing 0.3-5.3 mm. high and 0.7-3,0 mm. wide.A
Inflorescences axillary, terminal, leaf-opposed, or 90° from the leaf, umbellate, subcapitate, paniculate, spicate or corymbiform, cymose, 0.6-34 cm. long, the peduncle 0-11 (-16) cm. long, sometimes with a primary branch 0.2-5.2 (-7.0) cm. long, a secondary one up to 2.0 (-4.0) cm. long, a tertiary one up to 1.6 (-3.0) cm. long, and rarely a quaternary one up to 2 cm. long, the pedicel 0-14 (-19) mm. long; bracts 0.5-12.2 mm. long, 0.1-3.9 (-14) mm. wide, sometimes 2-3 immediately subtending each flower, at other times at the base of the pedicel, sometimes 2-3 united part way; flowers: few to numerous, fertile stamens 5, antepetalous, staminodes usually absent, sometimes 5, alternate with the stamens, 0.1-1.2 mm. long, usually dentiform, sometimes elongated, the anthers 0.4-2.6 mm. long, 0.3-1.4 mm. wide, oblong, emarginate at both ends, sometimes nearly to the middle from the apex, the carpels 5, rarely 6-8, antepetalous, styles filiform, sometimes slightly clavate at the apex, ovules 2 per carpel.
Calyx quinquefid, valvate in aestivation, persistent, usually green, sometimes rose, rose purple, yellow, orange, red, or pinkish brown, sometimes canescent, sometimes membranous, 1.4-15.0 mm. long, 2.1-10 mm. wide, the teeth 0.4-7.8 mm. long and 0.2-4.8 (-5.5) mm. wide, sometimes accrescent, becoming up to 36 mm. long and 19 mm. wide, with teeth up to 12 mm. long and 10 mm. wide, the teeth usually deltoid-acute or deltoid-acuminate, sometimes ovate or nearly linear, hirsute, tomentulose, or sericeous, sometimes ciliate, hairs simple, stellate, glandular, or forked, 0.05-2.3 (-4.0) mm. long, the sinus usually acute, sometimes rounded to truncate; petals purple, pink, purple distally and yellow or orange proximally, yellow, orange, white, blue, red, white with red stripes, or violet, 2.7-17.4 mm. long, 0.8-9.5 mm. wide, usually obovate or oblanceolate, sometimes obdeltoid, obovate-oblong, elliptic, oval, ovate or oblong, cuneate or spatulate, free of the staminal tube or attached to it for 0.3-5.0 mm., the claw 0-6.5 mm. long, rarely glandular tissue present between the calyx and corolla, with lobes extending between the bases of the petals, sometimes a few glandular, simple, forked, or stellate hairs on the petals. Longistylous form. Stamens 2.4-7.0 (-9.0) mm. long, the filaments united up to the anthers or free for 0.2-3.0 mm., sometimes a few hairs at the base of the staminal tube; pistil 2.6-10.9 (-12) mm. long, the styles free for 1.2-6.7 mm., to the ovary or united for 0.3-4.0 mm., papillose at the apex for 0.5-2.5 mm. Brevistylous form. Stamens 2.8-11.3 mm. long, sometimes with a few hairs at the base of the staminal tube, the filaments free for 0.5-7.5 mm.; pistil 2.3-6.9 (-8.0) mm. long, the styles free for 0.8-5.3 mm, to the ovary or united for 0.2-3.0 mm., papillose for 0.3-1.0 mm. at the apex.
The flowers of several species in the section Melochia not dimorphic, stamens and pistils 1.7-3.2 mm. long, the filaments free for 0-1.2 mm., the styles free for 0.6-1.2 mm., to the ovary or united for 0.1-0.3 mm.
Fruit schizocarp or capsule, 2.4-10,5 (-12) mm. long, 2.9-17.0 (-22) mm. wide, subglobular and pentagonal, pyramidal and pentapterous, ovoid or oblong, the sulci between the carpels shallow to deep, extending a fifth to half way to the center of the fruit, usually hirsute, tomentulose, or sericeous, subglabrous to canescent, hairs stellate or simple, sometimes also forked or glandular, 0.1-1.6 mm. long, the stipe 0-6.7 mm. long; dehiscence septicidal, loculicidal, or both; seeds brown to black, 1 or 2 per cell, 1.4-3.9 mm. long, 0.9-2.5 mm. wide, usually trigonal, the dorsal surface rounded and the sides flat, sometimes obovate, sometimes somewhat flattened, in one section the seed may have an ascending membranous wing 0.3-5.3 mm. high and 0.7-3,0 mm. wide.A
Discusión taxonómica
Presl (1836) propone el género Physodium, diferenciándolo de Melochia por presentar un cáliz inflado y cerrado, anteras lineares, acuminadas y una cápsula estipitada. Bentham y Hooker (1863) al igual que Standley (1923) y Hutchinson (1967) aceptan esta propuesta. Sin embargo, Goldberg (1967) en su trabajo reconoce 5 secciones para el género Melochia: sección Physodium (C. Presl) Goldberg, con cáliz acrescente, frutos globosos y estípite largo; sección Pyramis Goldberg, frutos globosos u ovoides, aquillados dorsalmente e inflorescencias axilares; sección Melochia (L.) Goldberg, frutos globosos o pentagonales, sésiles, dehiscencia septicida; sección Mougeotia Griesb., frutos globosos o pentagonales, con pedúnculos a veces ausentes, dehiscencia septicida y semillas aladas; sección Visenia Schumann, frutos oblongos u ovoidales, pedúnculo siempre presente, con dehiscencia parcialmente septicida, semillas frecuentemente aladas. Dejando al género Physodium como representativo de la primera sección. Dorr & Barnett (1989) estudian la sección Physodium, endémica de México, que incluye a Melochia adenodes Goldberg, M. corymbosa (C. Presl) C.F.W. Meissn. ex Steud. y M. oaxacana Dorr & L.Barnett. Los estudios filogenéticos recientes de Whitlock et al. (2001) incluyen algunas especies de Melochia en la tribu Hermannieae junto con Hermannia L. y Waltheria L.
Género con 68 especies en el mundo, 12-18 en México.B
Género con 68 especies en el mundo, 12-18 en México.B