Ipomoea descolei O'Donell

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

100. Ipomoea descolei O'Donell , Lilloa 23: 440. 1950. ( O’Donell 1950a: 440)

Argyreia hirsuta Hook., Bot. Mag. t. 4940. 1856. (Hooker 1856: t. 4940), nom. illeg., non Argyreia hirsuta Wight & Arn. (1837) . Type. t. 4940 in Bot. Mag. (lectotype, designated here).

Argyreia choisyana [Hort. [Paris] ex Regel & Körn., Index Seminum (St. Petersburg) 1858: 40. 1859. (Regel and Kornikoff 1859: 40), non Ipomoea choisyana Wight ex C.B. Clarke (1883) . Type. Based on Argyreia hirsuta Hook.

Type.

ARGENTINA. Misiones, Dept. San Ignacio, G.J. Schwarz 3472 (holotype LIL001238).

Description.

Perennial herb from a tuberous rootstock, stems stout, decumbent (occasionally twining at tips), densely tomentose with yellowish or whitish hairs. Leaves petiolate, 7-18 × 6-16 cm, ovate, cordate with rounded auricles, apex obtuse and mucronate, margins undulate, dentate or sinuate, adaxially yellow-green, tomentose, abaxially grey-tomentose, the venation highlighted; petioles 2-12 cm, tomentose. Inflorescence of long-pedunculate, few-flowered axillary cymes; peduncles 5-20 cm, tomentose; bracteoles 10-25 × 2-4 mm, linear-lanceolate, attenuate, tomentose, caducous; secondary peduncles, if present 20-27 mm; pedicels 5-20 mm, densely pilose; sepals slightly unequal, outer 12-16 × 7-9 mm, elliptic, acute and mucronate, densely pilose; inner 5-6 mm wide, oblong-elliptic, obtuse, margins broad, glabrous, scarious; central area pilose; corolla 8-9 cm long, funnel-shaped, pink, pilose with yellowish hairs; limb 5 cm diam. Capsules 11-13 mm long, ellipsoid to subglobose, glabrous; seeds 7-8 × 5 mm, densely tomentellous.

Illustration.

Figures 5A , 66 ; O’Donell (1959b: 149).

Distribution.

A plant of cerrado-like grassland, nearly endemic to Misiones and Corrientes provinces in NE Argentina. Records from Bolivia are errors.

ARGENTINA. Corrientes: Santo Tomé, T.M. Pedersen 5453 (E, K, S); T.S. Ibarrola 1275 (LIL, NY, S). Misiones: Candelaria, M.E. Rodríguez 01081 (CTES); G.E. Barboza et al. 419 (CORD, CTES, SI); R. Vanni & Radovanovich 1088 (CTES, K); E. Ekman 1430 (S); Medina 148 (LIL, S)

PARAGUAY. Itapuá: Encarnación, Campo Cambyretá, Pavetti & Rojas 10896 (LIL).

BRAZIL. Rio Grande do Sul: A. Sehnem 3583 (SI).

Lectotypification.

Argyreia choisyana has been correctly identified with Ipomoea descolei (Austin et al. 2015) . The specimen at St Petersburg (LE00009100) is not a very good match but is cited by Staples and Traiperm (2017: 470) as holotype of Argyreia choisyana . However, Argyreia choisyana is clearly based on the plate of Argyreia hirsuta in the Botanical Magazine (Hooker, WJ 1856: t. 4940), which was painted from a plant grown from seed sent from Paris as " Argyreia choisyana ". The plate in the Botanical Magazine looks a better match for Ipomoea descolei and is here selected as the lectotype of Argyreia hirsuta Hook. , as no specimen has been traced at Kew. Seeds were clearly sent from Paris to London and St Petersburg but how they arrived at Paris is unknown. It is not entirely fanciful that the seeds were sent to Paris by Bonpland, who had settled at Corrientes after his release from imprisonment in Paraguay. He may well have seen the horticultural potential of this spectacular Ipomoea , which is endemic to the region.

Note.

A very distinctive species because of the dense yellowish indumentum that covers all parts, the tendency of the leaves to be undulate or sinuate-lobed and the trailing habit.

Figures

Figure 5. Sepals of Ipomoea species. A Ipomoea descolei B I. paraguariensis C I. australis D I. purpurea (left), I. nil (right) E I. incarnata F I. pintoi G I. maurandioides H I. pubescens. Photographs of A by Hector Keller; B and G by T. Carruthers; C (Wood et al. 27708); E (Wood 27756) and H (Wood 27675) by Beth Williams; D by John Pink; F (Queiroz 15956) by Hibert Huaylla.

Figure 66. Ipomoea descolei. A habit from apex of stem B habit from near base of stem C adaxial leaf surface D abaxial leaf surface E outer sepal F middle sepal G inner sepal H corolla opened out to show stamens J ovary and style K calyx in fruit. Drawn by Rosemary Wise from Pedersen 5453.