Cremocarpon as circumscribed by Bremekamp has its center of diversity in Madagascar (8 species), but is also found in the Comores (1 species) and New Caledonia (1 species). Bremekamp's Cremocarpon is unusual morphologically and often overlooked. It is similar to Psychotria s. str., with raphides in its tissues; a shrub habit; deciduous to persistent stipules that are interpetiolar or fused around the stem and triangular to rounded or bilobed on each interpetiolar side of the stem; terminal, cymose, pedunculate inflorescences with reduced bracts; 4- or 5-merous distylous flowers; salverform white corollas with valvate lobes; bilocular ovaries with a single basal ovule in each locule; and seeds with or without ruminate endosperm. However the species included in Cremocarpon differ from typical Psychotria in its unusual schizocarpous fruits. These fruits are ellipsoid to oblong-ellipsoid and ultimately apparently dry rather than fleshy. At maturity these fruits split along the septum into two mericarps supported by a branched fibrous carphophore; the mericarps disperse and the carpophores remain on the plant, where they disintegrate. Each mericarp corresponds to a pyrene plus the fruit wall, and is indehiscent and apparently lacks preformed germination slits (PGS's; Piesschaert, 2001). See Bremekamp (1958: p. 148) for an analytic illustration. The carpophore varies from simple to branched, and is generally in the shape of a horse shoe with the pedicel connected at the rounded basal portion. The species described in Cremocarpon are readily recognizable in the fruiting stage but are often overlooked in flower or immature fruit. They can often be recognized in young fruit, after the corolla has fallen but before the formation of the mericarps is evident, by the disk that becomes enlarged or broadened. In species (the Cremocarpon boiviniana group) the disk becomes widened and quite smooth. Its separation from disks of typical Psychotria can be subtle, but in several species (the Cremocarpon lantzii group) the disk and calyx limb both enlarge as the fruit develops, with the disk equal to or a longer than the persistent calyx limb.

Otherwise Cremocarpon is very similar to species included in Psychotria. These groups differ in fruit type, with fleshy drupaceous fruits in Psychotria. Also in many species that have always been included in Psychotria the stipules are deciduous exposing a line of persistent trichomes along the stipule scar, and similar adaxial trichomes are also present in the species that were classified in Cremocarpon but the stipules of the Cremocarpon species are generally persistent or when they do fall, the adaxial stipule trichomes also fall off. The disk in the species classified in Psychotria generally shrinks as the fruits mature, and is usually not at all well developed on the mature fruits. Also the species that have been included in Cremocarpon generally have well developed peduncles that position the inflorescences and especially the infructescences beyond the leaves; a similar arrangement is found in some species of Psychotria, but many Psychotria species have quite short inflorescences. Razafimandimbison et al. (2014) studied this group using molecular data, and found the species that Bremekamp separated in Cremocarpon all included in the Madagascar clade of Psychotria and separated into several species groups, with the groups separated and more closely related to various species of Psychotria than to other species that were classified in Psychotria. Accordingly Razafimandimbison et al. synonymized Cremocarpon with Psychotria, and concluded that these unusual schizocarpous fruits have arisen more than once in Psychotria.

The species included in Cremocarpon are similar to and apparently very closely related to Pyragra, with similar schizocarpous fruits, persistent stipules, and well developed peduncles, and also a similar habitat and general aspect to species of the Cremocarpon boivinianum group. Bremekamp distinguished these genera based on fruit form, with the fruits of Pyragra ovate and strongly laterally flattened vs. ellipsoid and rounded or only weakly laterally flattened in Cremocarpon; also Pyragra generally has the inflorescences displaced to pseudoaxillary soon after flowering. In Madagascar the deciduous species included in Cremocarpon and Pyragra are easily confused with several similar species that Bremekamp included in Apomuria, which are also found in dry habitats; these are easily separated in fruit, when the species he included in Apomuria have subglobose to didymous, fleshy, red drupes, but in flower these species are often confused in the herbarium and generally separable only by the stipule characters of the individual species.

The species included in Cremocarpon from Madagascar and the Comores can be separated into three groups, which were discussed but not formally named by Bremekamp. One of these is the Cremocarpon lantzii group, which has well developed, thick-textured leaves, sessile or very shortly pedicellate flowers, fruit with the calyx limb and disk enlarged, and humid forest habitats. Cremocarpon rupicola from New Caledonia is quite similar to the Madagascar species of this group. Another group of species, the Cremocarpon boivinianum group, has thin-textured, medium to often rather small leaves that are frequently borne on shortened lateral stems, well developed slender peduncles and pedicels, fruits with the disk broadened and flattened, and a dry forest habitat; these species are very similar to the species included in Pyragra. Bremekamp separated Pyragra based basically on fruit shape, and the species of Pyragra seem closely related to the species of the Cremocarpon boivinianum group as noted by Piesschaert (2001). The third group comprises only Cremocarpon trichanthum, which is not markedly similar to any of the other species of its genus in general aspect or several morphological characters. It differs from the other species that were included in Cremocarpon in particular in its dense pilosulous pubescence, numerous flowers that are closely grouped, and triangular stipules. It was said by Bremekamp to have ellipsoid fruits with carpophores and mericarps similar to those of other Cremocarpon species, however this has not been confirmed in the images seen so far of the specimens studied by Bremekamp. The fruits of several specimens annotated by him with this name and cited in the protologue in fact appear to be fleshy and indehiscent. The fruits of this species do have thickened fibrous structures that encircle the fruit and are sometimes branched, and overall are quite similar to the carpophores of other Cremocarpon species. Such structures have been documented by Piesschaert in other species of Psychotrieae with fleshy fruits, and were suggested by him (2001: 326-327) to be structures that are found in most Psychotrieae fruits and that developed into the carpophores of dry schizocarpous fruits.

For more taxonomic information see TROPICOS. For more information on individual species and synonymy, see the Madagascar Project. (To access that data, in the upper right of this web screen, click on "Choose Project", and then the corresponding database from that list.)

Author: C.M. Taylor. The content of this web page was last revised on 31 July 2014.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

• Bremekamp, C. E. B. 1958. Monographie des genres Cremocarpon Boiv. ex Baill. et Pyragra Brem. (Rubiacees). Candollea 16: 147–177.
• Bremer, B. & T. Eriksson. 2009. Time tree of Rubiaceae: Phylogeny and dating the family, subfamilies, and tribes. Int. J. Pl. Sci. 170(6): 766–793.
• Piesschaert, F. 2001. Carpology and Pollen Morphology of the Psychotrieae (Rubiaceae-Rubioideae). Ph.D. Dissertation, Catholic University of Leuven, Belgium.
• Razafimandimbison, S. G., C. M. Taylor, N. Wikström, T. Pailler, A. Khodabandeh & B. Bremer. 2014. Phylogeny and generic limits in the sister tribes Psychotrieae and Palicoureeae (Rubiaceae): Evolution of schizocarps in Psychotria and origins of bacterial leaf nodules of the Malagasy species. Amer. J. Bot. 107(1): 1102–1126.