Capirona includes one species of large trees (to 40 m tall) found in wet forests in the Amazon basin. Capirona has opposite well developed leaves (to 44 x 24 cm), well developed stipules that are fused around the stem, terminal cymose inflorescences, 5-merous flowers, well developed corollas 20-35 mm long with convolute lobes, bilocular inferior ovaries, and septicidal capsules with numerous winged seeds. Capirona is unusual in its stipules, which are persistent and characteristically split medially on each interpetiolar portion to produce two intrapetiolar segments at each node. The trunks are also distinctive and characteristic, with smooth green bark that flakes off in membranaceous yellow to brown pieces. Plants of Capirona vary notably between the juvenile and adult stages, at least in the western Amazon basin. The juvenile plants often have shortly petiolate obovate leaves with long-tapered bases and are densely pilose, while the adult plants are glabrous and have elliptic leaves on well developed petioles. Capirona has showy whitened to deep pink flowers in large cymes, and many plants also have well developed bright pink calycophylls though these are sometimes not present. The corollas are unusual in having longitudinally plicate tubes, which enlarge and become smoother at anthesis. The capsules are distinctive, with their rather large size increased by a persistent, well developed calyx limb that often enlarges as the fruits develop.

Capirona was studied in detail by Kirkbride (1985), who clarified the identities of some poorly known genera as synonymous with Capirona and recognized two species, Capirona decorticans and Capirona leiophloea, based on the presence vs. absence of pubescence. Kirkbride reported the glabrous plants as the more common and widespread, and the pubescent plants only from Suriname, French Guiana, and Pará in northeastern Brazil; he did not comment in particular about juvenile plants, which are usually pubescent even in areas where the adult specimens are all glabrous. Andersson later reviewed Capirona systematically and taxonomically, and classified this genus in the Tribe Calycophylleae (Andersson, 1995). Andersson also (1994) noted that plants with some amount of pubescence are actually found throughout the range of this species, and that the density and distribution of the pubescence varies and that he could find no other characters to separate species. Andersson therefore recognized one morphologically variable species of Capirona. A description and floristic treatment were subsequently published with a focus on the plants in northeastern South America by Taylor et al. (2004) and for the plants of the central Amazon basin by Taylor et al. (2007). 

Delprete also reviewed this species, and treated it (1999) as Capirona decorticans although he noted there than an older name existed, Condaminea macrophylla. Delprete subsequently (2020) studied in this species again, and transferred the name Condaminea macrophylla to Capirona. He also presented a description and floristic treatment, although with only limited access to material of this species from the western Amazon region and with no change in its known synonymy. 

In general aspect Capirona is similar to Dialypetalanthus and some species of Calycophyllum. Calycophyllum differs in its stipules that are triangular and interpetiolar; Dialypetalanthus differs in its smaller corollas with free petals and numerous stamens. Some species of Calycophyllum are also large and important timber trees with smooth green trunks similar to those of Capirona, and these species are all sometimes called "capirona" locally. Macrocnemum also has generally smooth, thin-barked trunks, along with erect interpetiolar flattened stipules. Capirona plants are sometimes confused with Malpighiaceae because of their intrapetiolar stipules, but Malpighiaceae has superior ovaries and free petals. Similar intrapetiolar stipules are also found in Elaeagia, which has small beaked capsules with angled seeds. In fruit Capirona resembles Ladenbergia, which has interpetiolar usually deciduous stipules and valvate corolla lobes. Pilose juvenile plants of Capirona are frequently not identified to genus, or even to family. In a molecular systematic study Kainulainen et al. (2010; as Condamineeae) found Capirona in the Tribe Dialypetalantheae, with its relationships in this group not entirely clear.

Author: C.M. Taylor
The content of this web page was last revised on 8 December 2022.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

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• Andersson, L. 1994. Tribe 1. Cinchoneae. 50: 1–82. In G.W. Harling & L. Andersson (eds.) Fl. Ecuador. University of Göteborg, Göteborg.
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• Delprete, P. G. 1999. Rondeletieae (Rubiaceae)—Part I (Rustia, Tresanthera, Condaminea, Picardaea, Pogonopus, Chimarrhis, Dioicodendron, Molopanthera, Dolichodelphys, and Parachimarrhis). Fl. Neotrop. Monogr. 77: 1–226.
• Delprete, P. G. 2020. A new revision of Capirona (Rubiaceae, Ixoroideae, Condamineeae), with a new combination and additional notes on typification of the names involved. Phytotaxa 443(1): 101–106.