Ipomoea cambodiensis Gagnep. & Courchet, 1915

Staples, George W., Traiperm, Paweena, Sugau, John B. & Pornpongrungrueng, Pimwadee, 2014, Ipomoea cambodiensis Gagnep. & Courchet (Convolvulaceae) recharacterised with notes on its distribution and ecology, Adansonia (3) 36 (2), pp. 351-357 : 352-357

Ipomoea cambodiensis Gagnep. & Courchet

( Figs 1 ; 2 )

Notulae Systematicae 3: 143. 1915. — Type: Cambodia. Kampot, 20.XII.1903, Geoffray 275 (syn-, P [ P00288062 ], photo seen); without locality, same date, Geoffray 275bis (syn-, P [ P00288063 ], photo seen) . — Laos. Xiagnabouli: Paklay , anno 1866-68, hvorel s.n. (syn-, P [ P00288064 ], photo seen) .

ADDITIONAL SPECIMENS EXAMINED. — Laos. Luang Prabang, along Hwy 13 between Luang Prabang city and Vientiane, near Km marker 331, where road crosses a small stream, 4.XI.2012, Staples et al. 1512 ( SING!, HNL!, KKU!, P!, A!); PK7 , Rr. Ban Khittot, 13.II.1969, Pedrono 40 ( P!) ; Ban Khi Mot , 2.XI.1969, Pedroño 132 ( P!) ; Champasak, Huay Palai , open area near stream, 19.II.2010, T.Wongprasert 102-42 ( BKF!) .

Vietnam. Ðong Nai province: Biên Hòa , I.1866, L . Pierre s.n. ( P!) .

Ŋailand. Udon Ŋani, Na Yung district, near entrance to Wat Ba Phu Kon , 29.XI.2013, Traiperm et al. 596 ( BKF!) . Malaysia. Sabah: Beluran distr., along Hwy. A4 on outskirts of Gambaron , 7.III.2010, Sugau et al. SAN-152863 ( SAN!, SING!) ; Ranau distr., outskirts of Kampung Tampios , 8.III.2010, Sugau et al. SAN-152872 ( KEP!, SAN!, SING!) ; between villages of Pinausok and Kundasang (nearer to latter), 10.III.2010, Sugau et al. SAN-152881 ( KEP!, SAN!, SING!) ; Kota Belud distr., near end of unpaved road from Kampung Kiau at the junction to Kampung Kaung , 11.III.2010, Sugau et al. SAN-152886 ( SAN!, SING!) ; Nabawan via Tenom , 20.II.1989, Tay, Shah & Tee 89-0418 ( SING!) .

DISTRIBUTION. — Borneo (Sabah), Vietnam, Ŋailand, Cambodia, Laos ( Fig. 3).

DESCRIPTION

Twining perennial herb to 5 m high or more. Stem and branches filiform, rooting at nodes when touching ground, drying striate-angulate, glabrescent or sparsely puberulent; innovations coppery red, fading through olivaceous green, to deep green at maturity. Leaves triangular-ovate, 5-14 cm long, 3-7.5(-10) cm wide, both sides sparsely hairy, especially along the veins; base deeply cordate;margins, especially towards the base, drying undulate-denticulate; apex acute to acuminate, mucronulate; secondary nerves three pairs basally and 3-4 more distally, ultimate nerves ± inconspicuous; underside of blade minutely dotted; petioles 1.5-9(-13.5) cm long, shortly hairy.Inflores - cences axillary, pedunculate, (1–)3-7(-10)-flowered; peduncle 0.8-1.9 cm; pedicels 1.5-2.5 cm; bracts oblong-acute, 2 mm long, subopposite. Flowers showy, diurnal, borne ± horizontally; buds apically silky hairy outside.Sepals unequal, ovate-obtuse, base subcordate, glabrous, drying verrucose-pitted below middle, smooth above;apex acute to obtuse,mucronulate, outer ones 4-4.5 mm, inner ones 6-7 mm long. Corolla funnel-shaped, 4.5-6(-6.8) cm long (when dry); tube base narrow, cylindrical, red-purple inside, widening abruptly above; limb vaguely 5-lobed or 5-angled, creamy white or pale yellowish, lobes triangular, very short. Stamens inserted near tube base; filaments unequal, 5-15 mm long, bases abruptly widened, papillose; anthers oblong, 4 mm long, white. Pistil included, slightly longer than stamens; ovary acuminate, glabrous, locules 2, biovulate; style filiform, stigmas capitate, biglobose, white. Fruiting sepals not accrescent in fruit, at length reflexed along pedicel, drying brown-black, margins paler.Capsule ovoid-conical, 15-17 mm long, dark brown, 4-valved, glabrous, tardily dehiscent, apex often apiculate by indurated style base. Seeds 4 or less, 7-9 mm long, woolly with long, wavy, gray-brown hairs.

DISTRIBUTION NOTE

Ŋe disjunct distribution from Vietnam to Sabah is unusual; no similar biogeographic pattern is known for Convolvulaceae .Indeed only one other plant with a comparable disjunct distribution is known: Alchornea sicca (Blanco)Merr.(Euphorbiaceae) ,disjunct between Indochina( Cambodia, Laos, Vietnam)and the Philippines (Luzon) ( Van Welzen & Bulalacao 2008). It is possible that the Sabah plants were introduced from Indochina at some point and have now become widespread and naturalized so as to appear native.Ŋe lack of herbarium specimens from Sabah prior to the 1950s (when Ooststroom first credited I.ochracea to “British North Borneo ”) could be significant in this regard. Searches in the BKF, K, SAN, and SING herbaria did not locate any Sabah material for I. cambodiensis other than the specimens cited above. Ooststroom (1958) did not cite the specimens he examined from Sabah; possibly these are in Leiden.

Ecology

In disturbed secondary forest, along roadsides, often near streams, ditches, or standing water; once collected at edge of a fruit tree orchard.

Elevation

c. 70–1158 m.

Phenology

Flowering: Feb., Mar., Nov.; fruiting: Feb., Mar.

Ŋe type specimen label reports the flowers open from morning to midday, and this agrees with what we observed in the field. Ŋe flowers are showy, pale yellow to creamy white, with a dark red-purple center inside the tube. Rather few fruits are produced in Sabah and these typically have less than four seeds. TAXONOMIC NOTES

Table 1 quantifies the important characters useful for distinguishing I. cambodiensis from I. ochracea : larger corollas (up to 6.8 cm long); paler whitish or cream corollas with deep red tube base inside; sepals unequal, 4-7 mm long with acute to obtuse, mucronate apex; finely sericeous midpetaline bands outside; and seeds covered in long, wavy, gray-brown hairs.

Ŋe presence of silky puberulous trichomes on the corolla is most evident on young buds, as these enlarge and the corolla later expands, the pubescence is less obvious; it is there when checked with a hand lens.Ŋe presence of hairy flower buds is uncommon in Asian Ipomoea ; only I. rubens Choisy , a rather rare aquatic species, has it. In fact, the specimen Tay et al. 89-0418 in SING was misidentified as I. rubens based on this bud character.

Ooststroom (1940: 523-524) first took up the name “ Ipomoea ochroleucea” Span. for plants from Timor; his description says the sepals are equal in length,broadly rounded to truncate,emarginate, with mucronulate point; the corolla is c. 4 cm long and sulphur yellow. Ŋis description agrees very closely with African populations of I.ochracea and reasonably well with naturalized populations from the Hawaiian Islands ( Austin 1990), as seen alive by the first author. Ŋis first description and distribution (i.e. only Timor is mentioned) was repeated in the Flora Malesiana account ( Ooststroom & Hoogland1953), with just an orthographic correction to the epithet: “ ochroleucea ” became ochroleuca. Later, in the series of corrections and additions to the Flora Malesiana account, Ooststroom (1958: 561) provided a new description for the species and included plants from North Borneo (now Sabah) and New Caledonia. Ŋis revised description reads rather differently and attempts to account for the larger flower size, differences in corolla color, and calyx proportionality of plants from Sabah relative to those from Timor. Still later Ooststroom (1972: 941), changed the name for this species to I. ochracea (Lindl.) G. Don.

During the same time period, Verdcourt (1958: 208-209) had published on the extraordinary variability of African plants that made it nearly impossible to identify some populations accurately; Verdcourt’s conclusion (1963: 117) was that Ipomoea ochracea intergraded with the closely related I. obscura ( L.) Ker Gawler. Indeed, it seems that these two species are at the centre of a species complex that is taxonomically difficult and needs further study. Ŋis is primarily an African complex with only I. obscura known (at that time) to extend as far eastward as Asia and the Pacific Islands. Ooststroom was very likely influenced by Verdcourt’s findings and thus chose to accommodate a greater range of variation in the Malesian plants he ultimately called I. ochracea . Quite apart from the morphological diversity, there is the extraordinary disjunction from East Tropical Africa to Timor. However some of the African forms of I. ochracea with bright yellow corollas have been moved around as horticultural subjects. One has to wonder if the original report of sulphur yellowflowered plants from Timor is such a horticultural introduction, the Portuguese having traded for centuries between East Africa and their colony on Timor. However, the plants from Sabah differ markedly on several morphological points noted above ( Table 1) and Ooststroom’s inclusion of them in a broadened concept of I. ochracea seems, in hindsight, ill-advised; we think they are much better placed with I. cambodiensis .

Ooststroom’s association of Malesian populations with I. ochracea makes sense on a broad scale, because the plants are clearly allied with this complex of species, but we would argue that I. cambodiensis should be recognized at species rank and is the more accurate placement for SE Asian and Bornean populations.

Ŋe status of the New Caledonian plants that Ooststroom (1958) mentioned requires further investigation to see if they are correctly placed in I. ochracea . Ŋe key and terse description in the Flore de la Nouvelle-Calédonie ( Heine 1984: 76-78) suggest that they are, but it would be essential to examine specimens to confirm this. Ŋe description for the New Caledonian plants differs in several respects from the Sabah and Lao ones. Perhaps the most significant example is the seeds are illustrated ( Heine 1984: 77) as glabrous with a tuft of hairs around the hilum, which is markedly different from the Lao and Sabah plants with their long, wavy hairs covering the entire seed surface.

Figures

FIG. 1. — Syntype specimen (Geoffray 275) of Ipomoea cambodiensis in P [P00288062].

FIG. 2. — Ipomoea cambodiensis Gagnep. & Courchet: A, Sabah plant (Sugau et al. SAN-152886), flower in frontal view (photo: J. B. Sugau); B, Sabah plant (Sugau et al. SAN-152886) flower in side view (photo: G. Staples); C, Laos plant (Staples et al. 1512) flower in side view (photo: K. Phoutthavong).