A foundation monograph of Ipomoea (Convolvulaceae) in the New World

Gynoecium

The style is elongate, equalling or extended slightly beyond the anthers and nearly always glabrous, even in species with a hirsute ovary. The only exception we are aware of is Ipomoea sidifolia, in which the hairs extend for a short distance upwards from the ovary. The style is usually included in the corolla but is exserted in species with a hypocrateriform corolla. The stigmas are characteristically biglobose, that is they are bilobed with each lobe globose and appearing fused. They sometimes appear simply globose. Triglobose stigmas are characteristic of the Pharbitis Clade but are not reported from all species in the clade. Somewhat elongate stigmas are reported from African species placed in Astripomoea Clade but also occur in three species of the Arborescens Clade: I. pauciflora, I. populina and I. wolcottiana.
The ovary is narrowly ovoid in shape and usually glabrous. A pubescent or comose ovary is rare and only commonly found in the Batatas Clade. Most species have a bilocular ovary with two ovules in each chamber. This correlates with a biglobose stigma. A few species (Pharbitis Clade) have a trilocular ovary each chamber with two ovules, this correlating with a trilobed stigma. In species of the Quamoclit Clade, in Rivea, Stictocardia and most species placed in Argyreia, the ovary is 4-locular but with a single ovule in each chamber. Very rarely other arrangements are noted. In Ipomoea decasperma (and I. longituba Hallier f. from Madagascar) the ovary is 5-locular with two ovules per chamber but it is not clear whether this is constant in all examples of these species. Ipomoea gilana is reported to have a trilocular ovary.

Fruit

The fruit may be an indehiscent, woody or somewhat fleshy structure or formed by a dehiscent capsule. In species with an indehiscent fruit, this is usually globose to ellipsoid in shape and may contain up to four seeds except in those species placed in Turbina where 1–2 seeds only are present. Indehiscent fruits are glabrous but some species placed in Argyreia have mealy fruits. In those species with a capsular fruit, the capsules may be globose, ovoid or conical in shape. Capsules are usually muticous but species with a prominent rostrate apex formed by the persistent style base are common. Most capsules are completely glabrous but in a few species, they are pubescent, pilose or comose, this correlating with a hirsute ovary (Ipomoea velutinifolia, I. dubia, I. sidifolia, I. dasycarpa, many annual species of the Batatas Clade). In the majority of species the capsule is bilocular with up to four seeds, though often less as a result of abortion. There are several exceptions. In the Pharbitis Clade capsules are usually trilocular and 6-seeded. Very rarely capsules have up to 10 seeds (I. decasperma). In the Quamoclit Clade the capsules are 4-locular but with only four seeds.
Seeds (Figure 11) are typically broadly oblong in outline and vary in size from species to species. Their colour (when ripe) can vary from black to varying shapes of brown, sometimes being distinctly reddish-brown. They can be completely glabrous, minutely covered in very short hairs (tomentellous), only visible under a microscope, pubescent, tomentose or, in many species, with prominent, usually white hairs which develop on the angles of the seeds, In a few cases the seeds are completely covered in matted woolly hairs (Ipomoea bombycina, I. eremnobrocha, I. isthmica, I. macrorhiza, I. jalapa). Although important in diagnosing species and species groups, the value of seeds as a taxonomic character is somewhat diminished by a number of factors. The seeds of many species are unknown; in some the marginal hairs are caducous so may appear absent (I. psammophila) and in others there may be more variability than can be demonstrated from the few fruiting specimens known (I. jalapa).