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Citrus ID






Balsamocitrus Sec. Afraegle Swingle (sec. Swingle and Reece 1967)

Cultivar or taxon


Afraegle (Swingle) Engler (sec. Swingle and Reece 1967; sensu Tanaka sec. Cottin 2002)



Swingle and Reece (1967) noted that "Swingle described Afraegle as a section of Balsamocitrus in 1912 and at the same time established the section Eubalsamocitrus for the typical species, B. dawei. The section Afraegle was raised to generic rank in 1915 by Engler."



Crown compact or dense, not weeping. First-year twig surface glabrous; second- or third-year twig surface mottled or striate; thorns straight; prickles absent or not persistent. Petiole glabrous, length short or very long, wings absent, or if present then narrow and adjoining blade. Leaflets one or three, margins crenate/crenulate or bluntly toothed, rachis wings absent, shade leaflet blades flat or weakly conduplicate, sun leaflet blades weakly or strongly conduplicate. Leaflets not scented when crushed. Fruit as broad as long or longer than broad; rind dark green (3), medium green (4), light green with some break to yellow (5), or green-yellow (6); rind texture smooth (1-3); firmness woody; navel absent.


Swingle and Reece (1967) provided the following additional notes on the genus:

"In his revision of the whole plant family Rutaceae, Engler described it (1931, p. 352) as follows (in translation): ‘Calyx small, 5-merous, persistent. Petals 5 linear, imbricate. Stamens about 20 with subulate filaments and anthers of about equal length, inserted in a broad lobed disk. Ovary short-ovate, roughened with glands, with about 8 locules, more or less, with numerous ovules in each locule; style shorter than the ovary with a long-ovate stigma. Fruits large, globose or pear-shaped, with a hardish shell, many-seeded. Seeds large, up to 1.7 cm long, 1 cm thick, ovate, or wedge-shaped at the base, rounded or bluntly angled. Trees with trifoliolate, long-slender leaflets narrowed toward both ends, with axillary thorns and small 6-10-flowered racemes.’


This West African genus of Hard-Shelled Citroid Fruit Trees contains three or four species of medium- or large-sized trees, including A. (?) asso, the tallest African species of the orange subfamily. Afraegle is more advanced from an evolutionary point of view than Balsamocitrus in that it has stamens three to four times as numerous as the petals (instead of only twice as many). Afraegle is related to Aeglopsis; the latter, however, has simple leaves and only six locules in the ovary, instead of eight to ten, as in Afraegle."


The monophyly of the bael-group of Swingle and Reece (1967)--i.e., Aegle, Aeglopsis, Afraegle, and Balsamocitrus--is supported by the results of Bayer et al. (2009).



Afraegle is closely related to Aegle, Aeglopsis (not known in our area), and Balsamocitrus (not known in our area). The two introductions in our area--Aegle and Afraegle--can be distinguished as follows (sec. Swingle and Reece 1967):

1. Locules 8-20; seeds woolly...Aegle
1. Locules 6-8; seeds glabrous...Afraegle



Cottin, R. 2002. Citrus of the World: A citrus directory. Version 2.0. France: SRA INRA-CIRAD.

Engler, A. 1931. Rutaceae. In: Engler, A., and K. Prantl. Die natürlichen Pflanzenfamilien. 19a: 187–359. Engelmann, Leipzig.

Swingle, W.T. and P.C. Reece. 1967. The botany of Citrus and its wild relatives. In: Reuther, W., H.J. Webber, and L.D. Batchelor (eds.). The Citrus industry. Ed. 2. Vol. I. University of California, Riverside.



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Citrus ID Edition 2
October, 2011