Catesbaea includes about 17 species of distinctive, small-leaved, spiny shrubs and trees found in dry vegetation. It is characterized by elongated monopodial stems nearly always with regularly developed, decussate, unbranched spines; relatively small leaves (0.4--2.5 cm); short, triangular, usually persistent, often papery stipules that are usually shortly fused around the stem; axillary, 4-merous flowers that are solitary or few and fascicled at a few to numerous nodes along the stem; narrow calyx lobes; yellow to white corollas with the lobes thinly imbricated; and baccate fruits with two to several ellipsoid seeds. Catesbaea is characteristically found on open limestone substrates, and often near coasts in areas washed with salt spray or brackish water. Catesbaea parvifolia is the most widespead and commonly collected species, though it cannot be considered a particularly common species; Catesbaea longispina is the most widespread species in Cuba. Several Catesbaea species have remarkably large showy flowers, and Catesbaea spinosa is occasionally cultivated as an ornamental.
The spiny structures of Catesbaea are called spines here following general Rubiaceae terminology, but morphologically these are thorns. The spines are terminal on axillary short-shoots, and are sparsely to densely developed in all of the species. Most Catesbaea plants are quite sharply savagely spiny. In a few species these spines are enlarged and at least sometimes photosynthetic, with the accompanying leaves quite small and deciduous in Catesbaea nana and Catesbaea phyllacanthus. Paudyal et al. (2018) describe plants of Catesbaea as often scandent or weakly climbing, but many plants actually are erect (e.g., Catesbaea melanocarpa in the Virgin Islands). The anthers appear on some specimens to be dorsifixed just above the base, but on many flowers the base of the anther separates at or shortly after anthesis into a shortly sagittate form leaving the filament now inserted at the base. The genus is generally characterized as having several ovules and seeds per locule, but one species, Catesbaea gamboana, was described as having solitary ovules.
Correll & Correll (1982: 1381, fig. 602) presented a figure with a good analysis of the striking species Catesbaea spinosa. The genus Catesbaea has not been studied as a whole, and the ecology of its individual species does not appear to have been much studied or documented in formal publications. Several of its species are considered locally endangered or threatened (e.g., Catesbaea parviflora in Florida, Catesbaea melanocarpa in the Virgin Islands), and Catesbaea phyllacanthus is considered extinct.
Catesbaea is notable, however, for the unsually wide range of corolla size and form. Its corollas range from 1--20 cm long, and have a range forms that are, notably, variously similar to some other Chiococceae genera: shorly funnelform with well developed lobes as in Chiococca (e.g., Catesbaea fuertesii, Catesbaea parviflora), tubular (e.g., Catesbaea flaviflora), funnelform and plicate with short broad lobes as in Portlandia (Catesbaea grayi), enlarged, elongated, and campanulate as in Cubanola (e.g., Catesbaea ekmanii), or enlarged with an elongated tube and funneform upper part as in Osa (Catesbaea spinosa). The large-sized flowers are few on a stem, pendulous, and probably nocturnal, while the relatively short flowers are numerous on a stem, spreading, and perhaps diurnal.
Catesbaea has centers of diversity in Hispanola, where Liogier (1995) recognized 7 species, and Cuba, where Borhidi et al. (2017, 2018) recognized 10 species. Some of these species were incompletely known to these authors. Many of these were distinguished by flower and fruit characters, but some were separated by leaf details (Liogier, 1995) and number of ovules per locule (both authors). Several Catesbaea species were originally described as having solitary ovules and seeds and are diagnosed thusly by these two modern authors, in contrast to the description of the genus in all sources that states only that Catesbaea has several ovules per locule. The number of seeds per locule was used by several authors to distinguish Catesbaea parrviflora in different regions, with different numbers of seeds ascribed to it in the different regions. For the whole genus, ovule and seed number seems to deserve further study (Catesbaea was not studied in Aiello's 1979 detailed studies of ovary arrangement). Few Cuban specimens were available for this current review, and the taxonomy of the Cuban plants is catalogued following Borhidi et al. (2017, 2018) but not evaluated here.
Catesbaea was of uncertain systematic position within Rubiaceae for some time, but molecular studies have found its relationships with genera now in the the recently clarified Chiococceae. Most recently, Paudyal et al. (2018) found the species Catesbaea they studied as a well-supported monophyletic group with the odd monotypic Cuban genus Phyllacanthus nested within it. The single species of Phyllacanthus was originally described in Catesbaea, but separated by some later authors based on its unique spines (discussed above). Its inclusion within Catesbaea in Paudyal et al.'s analysis maps these odd spines as an autoapomorphy. Overall, Paudyal et al. found Catesbaea as sister to a clade comprising the Greater Antillean genera Portlandia and Isidorea, and these three genera all grouped on a larger clade with Nernstia of Mexico, Osa of southern Central America, and Cubanola of the Greater Antiells.
Catesbaea is similar to some species of Scolosanthus, which differs in its usually branched spines, solitary ovules and seeds in each locule, and drupaceous fruits with the two planoconvex seeds encased a a papery but distinct endocarp layer.
Author: C.M. Taylor.
The content of this web page was last revised on 7 September 2021.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml