Ipomoea tuboides O. Deg. & Ooststr.

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

264. Ipomoea tuboides O. Deg. & Ooststr. , Fl. Hawaii, fam. 307. 1940. (Degener 1932-1940: fam. 307)

Ipomoea tuboides var. pubescens O. Deg. & Ooststr. in O.Deg., Fl. Hawaiiensis , fam. 307. 1940. (Degener 1932-1940: fam. 307). Type. HAWAII. Big Island, between Pu’awa’awa’a and Hu’ehe’e, O. Degener 6006 (holotype BISH1006750).

Ipomoea tuboides forma irregularis O. Deg. & Ooststr. [as var. pubescens forma irregularis] in O. Deg., Fl. Hawaiiensis, fam. 307. 1940. (Degener 1932-1940: fam. 307). Type. HAWAII. Big Island, between Pu’awa’awa’a and Hu’ehe’e, O. Degener 6020 (holotype BISH1006751, isotype BISH).

Ipomoea tuboides forma digitata O. Deg. & Ooststr. [as var. pubescens forma digitata ] in O. Deg., Fl. Hawaiiensis, fam. 307. 1940. (Degener 1932-1940: fam. 307). Type. HAWAII. Big Island, between Wai’ohinu and Ka’alu’alu, O. Degener 5988 (holotype BISH1006753, isotype BISH).

Type.

HAWAII. Oahu, O. Degener & Y. Nitta 5981 (holotype BISH1006749; isotypes BISH, F, GH, MASS, MO, NY, S, US, WIS).

Description.

Prostrate or twining perennial, stems slender, woody below, glabrous except for small green protuberances. Leaves petiolate, 4-7 × 4-6 cm, ovate, obtuse or acute and mucronulate, cordate, margin entire, toothed, sinuate or 3-lobed, green and glabrous on both surfaces; petioles 2.3-4.7 cm, false stipules sometimes present. Inflorescence of solitary pedunculate, axillary flowers; peduncles 1-1.5 cm; bracteoles 5-6 mm, caducous; pedicels 1.5-2.5 cm; sepals slightly unequal, outer 7-8(-15) × 3-4 mm, oblong-elliptic, glabrous, margin scarious, becoming reflexed in fruit, inner 9-10(-22) mm, obtuse to mucronate with broad scarious margins; corolla white with lilac tinge, weakly salverform, the basal cylindrical tube narrow, 2.5 cm long and 0.75 cm wide, the limb 4.5-5 cm wide, glabrous, stamens included. Capsules ovoid-conical, glabrous; seeds trigonous, pubescent with woolly marginal hairs.

Illustration.

http://www.starrenvironmental.com/images/search/?q=Ipomoeatuboides

Distribution.

Endemic to the Hawaiian Islands where it grows on lava flows.

UNITED STATES. Hawaii: J. Lau & C. Cory 2498 (BISH, FTG); Moloka’i, Kamakou Reserve, L.W. Cuddihy 1218 (BISH). Lanai, G. Munro 945 (BM, K); Maui, F.R. Fosberg 48346 (K, US); O. Degener 25100 (BISH, K); Oahu, O. Degener 5978 (K), 27905 (E).

Note.

This Hawaian endemic is of considerable interest as molecular studies ( Muñoz-Rodríguez et al. 2019) show its nearest relatives are Ipomoea retropilosa , I. chenopodiifolia and I. leucotricha , and, more distantly, I. decasperma and I. orizabensis . Ipomoea tuboides presumably arrived in Hawaii as a result of long-distance dispersal and subsequently evolved into a distinct species.

The floral dimensions in the protologue are much larger than in the specimens we have examined.

This is one of a number of species in which extrafloral nectaries have been reported (Keeler 1985) but this is something of an evolutionary curiosity in this case as there are no native ants in Hawaii.