Ipomoea hartwegii Benth.

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

133. Ipomoea hartwegii Benth. , Pl. Hartweg. 15. 1839. (Bentham 1839-57: 15)

Ipomoea albidiflora Matuda , Cact. Suc. Mex 18 (3): 78. 1973. (Matuda 1973: 78). Type. MEXICO. Michoacán, R. Hernández Magaña 700 (holotype MEXU00204487, isotype MEXU).

Type.

MEXICO. K.T. Hartweg 96 (holotype K000612756, isotypes BM, E, GH, K, NY, OXF).

Description.

Twining perennial herb to c. 2 m, stems woody below, white-pubescent; root tuberous, resembling a small turnip. Leaves petiolate, small, 2-4.5 × 1.8-3.5, ovate-deltoid, pubescent, glabrescent; petioles 0.6-4.3 cm, pubescent. Inflorescence of solitary flowers (rarely in cymes with up to 3 flowers); peduncles 2.5-16 cm, glabrous or pubescent; bracteoles early caducous, not seen; secondary peduncles (if present) 1-3 cm; pedicels 10-30 mm, glabrous; sepals slightly to very unequal, scarious-margined, outer 6-8 × 2. 5-3 mm, oblong to narrowly elliptic, obtuse, abaxially hispid with bulbous-based hairs (rarely glabrous), inner 7-9 × 3-4 mm, oblong-obovate, obtuse, rounded or retuse, with broader scarious margins, glabrous; corolla 4.5-8 cm long, funnel-shaped, white with lavender flush, (sometimes pink), glabrous, limb 4-7 cm diam. Capsules 7-12 × 6-9 mm, ovoid, glabrous; seeds black, 7-8 mm long, shortly pubescent on the angles.

Illustration.

Figures 3D , 78 .

Distribution.

Endemic to central Mexico, where it grows in scrub and rough grassland at around 2000-2100 m.

MEXICO. Chihuahua: Río Mayo, Guasaremos, H.S. Gentry 1558 (ARIZ), ibid., 2333 (ARIZ, MO). Est. México & Dist. Fed.: Temascaltepec, Cerro Muñeca, G.B. Hinton 1382 (BM, K, MO), ibid., Ipericones, G.B. Hinton 8083 (K, P, S). Guanajuato: M. Doblado, E. Carranza & E. Pérez 4938 (IEB, MEXU); La Presa del Chupadero, E. Ventura & E. López 9550 (IEB, MEXU); Coroneo, E. Carranza 5087 (IEB, MEXU). Guerrero: just N. of Arteaga, D.F. Austin & F. de la Puente 7691 (FTG). Jalisco: 5 miles E of Zapotlanejo, D. Tuttle 279 (ARIZ); Tepatitlán-Pegueros, R. Guzmán et al. 950 (MEXU). Michoacán: Mun. Morelia, J. Santos Martínez 2228 (IEB, MEXU, MICH); San Bernardo E. Carranza 5546 (IEB, MEXU). Morelos: Cuernavaca, C.G. Pringle 13779 (ARIZ, S). Nayarit: Santa María del Oro, H.S. Gentry 11012 (ARIZ); Tepic, R. Kral 27530 (MO). Querétaro: San Juan del Rio, C.G. Pringle 10028 (BM, K, MEXU, MO, S); Humilpan-El Pueblito, E. Argüelles 3220 (MEXU). San Luís de Potosí: Guadalcázar, R. Torres Colin 15218 (MEXU). Sinaloa: Villa Unión, R.L. Oliver et al. 727 (MO). Zacatecas: Coulter 1022 (K).

Notes.

Ipomoea hartwegii is a poorly understood species. It is characterised by the long-pedunculate 1-2-flowered inflorescence and the sepals with conspicuous scarious margins. The leaves are shortly petiolate, especially in contrast to the long-pedunculate flowers and the sepals are usually abaxially hispid with bulbous-based hairs, although in some specimens they are glabrous. It is not unlike a solitary-flowered small-leaved form of Ipomoea orizabensis .

Ipomoea hartwegii is quite frequently confused with I. proxima (as I. dimorphophylla ) but that species has a shortly pedunculate cymose inflorescence and the leaves are often lobed or at least with undulate margins.

• Species 134-141 are all Mexican species with white flowers and similar morphology although phylogenetic relationships between species have not been determined. Most but not all have hirsute sepals

Figures

Figure 3. Sepals of Ipomoea species. A I. pauciflora B I. bernoulliana C I. tentaculifera D I. hartwegii E I. murucoides F I. pantanalensis G I. hederacea H I. funis. Photographs of A (Harling et al. 15403) B (Standley 27496) C (Pringle 6702) D (Santos Martinez 2228 E (Pringle 6066) F (Pott 6399) G (McCarthy s. n.) H Andrieux 600 by John Baker.

Figure 78. Ipomoea hartwegii. A habit B outer sepal C inner sepal D corolla opened out to show stamens E ovary and style F habit G habit H outer sepal J inner sepal. Drawn by Rosemary Wise A from Santos Martinez 2228; B-E from Hinton 8083; F-H from Kral 27530.