Ipomoea proxima (M. Martens & Galeotti) Hemsl.

Wood, John R. I., Munoz-Rodriguez, Pablo, Williams, Bethany R. M. & Scotland, Robert W., 2020, A foundation monograph of Ipomoea (Convolvulaceae) in the New World, PhytoKeys 143, pp. 1-823 : 1

137. Ipomoea proxima (M. Martens & Galeotti) Hemsl. , Biol. Cent.-Amer., Bot. 2 (11): 1882. (Hemsley 1882: 392)

Calonyction proximum M. Martens & Galeotti , Bull. Acad. Roy. Sci. Bruxelles 12: 268. 1845. (Martens and Galeotti 1845: 268). Type. MEXICO. Oaxaca, Yavezia, H. Galeotti 1378 (holotype BR0008676993, isotype BR00008676115).

Ipomoea dimorphophylla Greenm. , Proc. Amer. Acad. Arts 33 (25): 482. 1898. (Greenman 1898: 482). Type. MEXICO. Morelos, near Cuernavaca, C.G. Pringle 6658; (lectotype GH n.v., designated (as type) by House (1908b: 257), isolectotypes AC, BKL, BM, BR, CM, E, ENCB, F, K, M, MEXU, MICH, MO, MSC, NY, P, PH, S, US, VT).

Ipomoea oaxacana Greenm., Publ. Field Mus. Nat. Hist. , Bot. Ser. 2 (8): 336. 1912. (Greenman 1912: 336). Type. MEXICO. Oaxaca, Cerro San Antonio, C. Conzatti 2057 (holotype F225829, isotype F).

Type.

Based on Calonyction proximum M. Martens & Galeotti

Description.

Perennial climbing herb with tuberous roots, stem pubescent but somewhat glabrescent, woody. Leaves petiolate, 2.5-4.5 × 1-4.5 cm, ovate, entire or shallowly 3-lobed, acute to acuminate, mucronulate, base truncate to shallowly cordate, adaxially thinly pubescent, glabrescent, abaxially pubescent to grey-tomentose; petioles 3-4.5 cm. Inflorescence of shortly pedunculate 1-6 flowered axillary cymes, sometimes developing on leafy side shoots; peduncles short, 0.3-1 cm puberulent; bracteoles caducous; secondary peduncles 5-10 mm; pedicels 10-20 mm, densely tomentellous, slightly thickened upwards; sepals slightly unequal, ovate to suborbicular, obtuse or rounded, coriaceous, glabrous, margin scarious, outer 5-6 × 4-5 mm, inner 6-8 × 5-6 mm; corolla 5-7 cm long, funnel-shaped, white, glabrous, limb 5-6 cm diam. Capsules subglobose, c. 10 mm, glabrous; seeds 7-9 mm, dark brown, with long white, marginal hairs.

Illustration.

Figure 81 ; Carranza (2007: 97).

Distribution.

Oakwoods in the mountains of south-central Mexico at 1800-2500 m.

MEXICO. Est. México & Dist. Fed.: Temascaltepec, Telpintla, G.B. Hinton 1139 (K); ibid., Tequisquipan, G.B. Hinton 1330 (K); ibid., Rincón, G.B. Hinton 1547 (K), ibid., 3262 (K). Guanajuato: Xichú, S. Zamudio 13627 (IEB). Guerrero: Vallecitos, Montes de Oca, G.B. Hinton 11480 (K). Michoacán: E. Carranza et al. 7625 (IEB); Aguililla, Apatzingan, G.B. Hinton et al. 15188 (GH, MO). Oaxaca: Ghiesbrecht s.n. (P); Cerro la Culebra, SW de el Enebro, P. Tenorio et al. 7147 (MEXU, MO); Santo Domingo Tonalá, A. Torres Hernández 505 (IEB); Pochutla, San Miguel del Puerto, J. Pascual 550 (ASU); Juchitán, A. Saynes & A. Sánchez 3609 (MO). Puebla: fide Carranza (2007). Querétaro: Tilaco, E. Carranza & Z. Ortega 7357 (IEB); Jalpán, E. Carranza et al. 7580 (IEB). San Luís de Potosí: C.A. Purpus 5403 (BM, MO).

Notes.

A poorly understood species characterised by the white corolla, truncate, pubescent, usually shallowly lobed leaves and shortly pedunculate cymes often arising on leafy side shoots. There is some variation in indumentum, specimens from Oaxaca having pubescent pedicels and sepals, whereas they are glabrous in the Temascaltepec specimens, Hinton 11480 from Guerrero and the lectotype of Ipomoea dimorphophylla . Ipomoea dimorphophylla was said by Austin et al. (2012) to be conspecific with Ipomoea batatoides and the two species were confused by Matuda, but I. batatoides is usually pink-flowered with glabrous leaves and is a plant of moist lowland forest.

This species is very close to Ipomoea scopulorum from NW Mexico differing in the shorter, more rounded, only slightly unequal sepals. It may intergrade with Ipomoea suaveolens but that species has spreading, stiff hairs on the stem and usually also on the pedicels and sepals as well as a narrowly funnel-shaped corolla.

Figures

Figure 81. Ipomoea proxima. A habit with flowers B stem C adaxial leaf surface D habit with buds E abaxial leaf surface F outer sepal G inner sepal H corolla opened out to show stamens J ovary and style K fruit. Drawn by Rosemary Wise A-C from Hinton 1330; D-J from Hinton 8262; K from Tenorio 7147.