Ipomoea arborescens (Humb. & Bonpl. ex Willd.) G. Don

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

124. Ipomoea arborescens (Humb. & Bonpl. ex Willd.) G. Don , Gen. Hist. 4: 267. 1838. (Don 1838: 267)

Convolvulus arborescens Humb. & Bonpl. ex Willd. , Enum. Pl. 1: 204. 1809. Type. MEXICO. Guerrero, between Acaguisootla and Chilpancingo, Humboldt & Bonpland (holotype B-W 03707-01, isotype P).

Argyreia oblonga Benth. , Bot. Voy. Sulphur 133. 1844 [pub.1845]. (Bentham 1845: 133). Type. MEXICO. Nayarit, Tepic, Sinclair s.n. (holotype K000612778).

Ipomoea oblonga (Benth.) Hemsl., Biol. Cent.-Amer., Bot. 2 (11): 391. 1882. (Hemsley 1882: 391).

Ipomoea murucoides var. glabrata Rose, Contr. U.S. Natl. Herb. 1: 107. 1891 (Rose 1891: 107), nom. illeg., non Ipomoea murucoides var. glabrata A. Gray. Type. MEXICO. Sonora, E. Palmer 316 (holotype US n.v., isotypes GH, K).

Ipomoea cuernavacensis House , Bot. Gaz. 43: 410. 1907. (House 1907b: 410). Type. MEXICO. Morelos, near Cuernavaca, J.N. Rose & J.H. Painter 6963 (holotype US00111384, isotype NY).

Ipomoea arborescens var. glabrata Gentry , Carnegie Inst. Wash. Publ.527: 212. 1942. (Gentry 1942: 212). Type. MEXICO. Sonora, San Bernardo, H.S. Gentry 1158 (lectotype ARIZ, designated by Austin et al. 2005: 1285, isolectotype MO).

Ipomoea arborescens var. pachylutea Gentry , Carnegie Inst. Wash. Publ.527: 213. 1942. (Gentry 1942: 213). Type. MEXICO. Sonora, Sierra de Alamos, H.S. Gentry 3000 (lectotype ARIZ, designated by Austin et al. 2005: 1285, isolectotypes K, MO, UC, US).

Type.

Based on Convolvulus arborescens Humb. & Bonpl. ex Willd.

Description.

Tree 5-15 m high, trunks often 50-70 cm diam., bark pale grey or yellowish ( var. pachylutea ), latex white, stems tomentellous with matted hairs, especially when young, glabrescent. Leaves 5-27 × 3-10 cm, ovate or lanceolate, cordate, acuminate, adaxially green, abaxially grey-tomentose, ± glabrescent except on veins, glands present at base of midrib; petioles 1.3-9 cm, tomentellous when young. Inflorescence terminal and axillary, composed 1-3-flowered raceme-like cymes borne on short branchlets, peduncles 1-5 mm; bracteoles 4-6 mm, ovate, caducous; pedicels 5-22 mm, widened upwards, tomentose; sepals subequal, 6-14 × 7-8 mm, elliptic, rounded, sometimes mucronate, tomentellous, glabrescent; corolla 4-6 cm long, subcampanulate to funnel-shaped, white with greenish tube and red throat, tomentose, at least in bud. Capsules 1.8-2.3 × 1.2-1.4 cm, ovoid, glabrous, shortly rostrate; seeds 9-16 mm long, the margins white-pilose with hairs c. 12 mm long.

Distribution.

Dry forest and scrub, mostly below 1000 m in western and central Mexico.

MEXICO. Chiapas: fide Breedlove (1986) (requires confirmation). Chihuahua: Barranca de Batopilas, La Bufa-Quirare, R.A. Bye 3415 (MEXU). Colima: D.H. Lorence et al. 3811 (MO); R. McVaugh & Koelz 1582 (MICH). Durango: Topia, S. Acevedo & D. Bayona 411(IEB). Est. México & Dist. Fed.: J.C. Montero Castro et al. 1255 (MO); Temascaltepec, Tejupilco, G.B. Hinton 447 (BM, K). Guerrero: Tepecoacuilco de Trujano, J. Smith & M. Ceuterick 0626 (ARIZ); V.W. Steinmann & J.M. Porter 4861 (ARIZ, IEB). Jalisco: R. McVaugh 25414 (MICH). Michoacán: Zitacuaro-Los Ríos, G.B. Hinton 13562 (K, MICH, MO, US); Aguilla, E. Carranza & I. Silva 6666 (IEB). Morelos: E.M. Martínez & E.F. Cabrera 11 (MO); Miacatlán, J. Ceja & A. Mendoza 1234 (IEB). Nayarit: Ixtlan del Rio, O. Tellez 9593 (MEXU). Oaxaca: King 1766 (MICH). Puebla: 5 miles SW of Tehuacan, R. Barr & C. Mason 23411 (ARIZ); Amatitlan, G. Huitron 2 (MEXU). Querétaro: San Joaquin, S. Zamudio 3222 (MEXU). Sinaloa: Cosala, A.L. Reina-G et al. 2006-10 (ARIZ); Concordia, R. McVaugh 23583 (MICH); J. González Ortega 173 (K); Las Mesas, Cerro Sirotato, H.S. Gentry 6144 (ARIZ, DES)- var. pachylutea . Sonora: Mun. Hermosillo, A.L. Reina-G & T.R. Van Devender 2000-889 (ARIZ); N of Hermosillo, K.F. Parker 8222 (ARIZ); H.S. Gentry 4888 (ARIZ)- var. pachylutea .

Notes.

The Berlin holotype of Convolvulus arborescens is a sterile plant cultivated in Berlin. The Paris isotype appears to be of the original collection made by Humboldt and Bonpland.

Argyreia oblonga Benth. is cited incorrectly as Ipomoea oblonga in IPNI, TROPICOS and Austin and Huáman (1996).

A rather variable species in which a number of varieties have been recognised. Var. pachylutea is often recognised by botanists who know it in the field. It is distinguished by its yellowish bark, larger and more pubescent leaves and larger flower parts, differences that are not readily discernible in the herbarium. It is found on rocky slopes and in low open woodland altitudes of 600-900 m in NW Mexico.