Stictocardia mojangensis

Nomenclature

Accepted name/Authority/Place of publication:

Stictocardia mojangensis (Vatke) D. F. Austin & Eich, comb. nova

Synonyms:

Ipomoea mojangensis Vatke in Linnaea 43: 515. 1882. - Holotype: Madagascar, "propeMojanga" [= Majunga, Mahajanga], 5.1880, Hildebrandt 3410 (B [destroyed]; isotype: P, n.v.) -Fig. 2.

Description

Habit:

Perennial climber, woody, the stems twining, white-pubescent-appressed when young, glabrescent, bleeding a brownish yellow syrup-like liquid (white in cultivated & regularly watered plants) when cut, older stems brown to gray

Leaves:

Leaves simple, with petioles 5-6 cm long,heterophyllous with ovate to pandurate forms (Fig. 2d); lamina coriaceous, broadly ovate to pandurate, 4.6-13.5 cm long, 4.6-10.7 cm wide, entire, the apex acute and mucronulate on pandurate leaves, acuminate on ovate leaves, the base almost truncate to cordate, sparsely pubescent above, white-appressed-pubescent below (often becoming black when dried), venation palmate below, pinnate above, with 5-8 pairs of secondary veins, conspicuous above and below; petiole canaliculate, 3.5-11.5 cm long, finely appressed-pubescent.

Inflorescences:

Inflorescences compound monochasial, 11-30-flowered, terminal on lateral branches, rachis 3-7 cm long.

Flowers:

Flowers on peduncles 0.5-1.5 cm long, glabrous; pedicels 1-1.3 cm long, glabrous, bracts scale-like, 0.5 mm long, triangular, glabrous. Sepals unequal, imbricate, the inner 3 longer than the outer 2, more or less orbicular, the outer 4-4.5 mm long and wide, inner 6-7 mm long and wide, more or less orbicular, basallyand apically rounded, the margins entire, coriaceous, scarious, glabrous, accrescent in fruit. Corollainduplicate-valvate and convolute, funnel-shaped, 3-3.5(-4) cm long, the limb white (pinkish or lavender when dried), the throat somewhat darker, glabrous on the mid-petaline bands, thetube cylindrical but with the apex constricted below the flaring limb, glabrous, shiny; the limb entirebut emarginate. Stamens included, unequal, 6-10 mm long (2 are 10 mm, 2 are 6 mm and I is7.5 mm), the filaments fused to the corolla tube 6-7 mm above base, glandular pubescent at the triangular base, the anthers 3-5 mm long, pollen large, echinate-clavate, pantoporate; nectary inconspicuous or absent. Ovary conic, 2-2.5 mm long and wide, tapering to the base of the style with a swollen attachment point, glabrous, the style single, 11-12 mm long, the stigma capitate, bilobed,1.5 mm wide.

Fruits:

Fruits capsular, reflexed when mature, 2-locular, 8-9 mm long (from sepal to baseof apiculum), 7-8 mm wide, exocarp dehiscent from the base to produce a "cap" with 4 lobes separating from the receptacle and falling separately, retaining a darker brown apiculum 3-5 mm long from the style base, endocarp whitish, with 2 cavities that retain the seeds.

Seeds:

Seeds (1-)2(-4), 4-6mm long, 3-4 mm wide, oblong to ovoid, dark brown, glabrous, covered with a honey-like liquid that dries to produce a shiny surface.

Author:

Daniel F. Austin and Eckart Eich

References:

Willdenowia, Bd. 31, H. 1 (Aug. 31, 2001), pp. 79-85

Biogeography, Ecology and Natural History

Distribution:

Known from the western part of Madagascar (Deroin 2001: fig. 20).

Ecology:

Flowering and fruiting in August, the dry season. At flowering there are no leaves on theplants. When grown in the greenhouse, shape and size of the leaves, as given here (Fig. 2d), are variable.The same variation occurs in wild plants according to Deroin (2001). Altitude: 10-800 m.

Author:

Daniel F. Austin and Eckart Eich

References:

Willdenowia, Bd. 31, H. 1 (Aug. 31, 2001), pp. 79-85

Chemical Data

Author:

Daniel F. Austin and Eckart Eich

Chemical Data:

With the exception of Stictocardia tiliifolia (= S. campanulata (L.) Merr.)chemical constituents of the genus are unknown. In contrast to S. tiliifolia, which produces ergotalkaloids in the seed (Chao & Der Marderosian 1973, Lee & al. 1979) and in the vegetative aerialparts (Schimming 2001), we could not find these compounds in S. mojangensis. This is remarkable, since ergot alkaloids are common constituents of the related genera Argyreia and Turbina(Argyreieae). Also present in S. mojangensis are a number of pyrrolidine, simple lipophilictropane and hydrophylic nortropane alkaloids (Table 1), common constituents of convolvulaceousspecies. All these alkaloids could be detected by the well-known GC-MS method, which has been already applied for other convolvulaceous species in our group (for experimental detailssee Jenett-Siems & al. 1998, Schimming & al. 1998). However, our detection of cyanogenicglycosides in the seeds and vegetative aerial parts of S. mojangensis by means of the Feigl-Angertest (Tantisewie & al. 1969) is unusual for the Convolvulaceae. Studies on structural details areunder investigation. To date unequivocal evidence of cyanogenic glycosides is available only for two Merremia species, viz. M. dissecta (Nahrstedt & al. 1990) and M. vitifolia (Jenett-Siems1996, Jenett-Siems & al. 1996). These glycosides have not been found in a number of otherMerremia species, or in other convolvulaceous genera (unpublished results).

References:

Willdenowia, Bd. 31, H. 1 (Aug. 31, 2001), pp. 79-85

Authorship for webpage

Editor:

Esmond Er

Contributors:

Convolvulaceae Unlimited

Convolvulaceae

Stictocardia mojangensis

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