Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.2.01.
Tribe: Cassieae.
Subtribe: Ceratoniinae.
Species Studied - Species in Genus: 2 studied; 2 in genus.
Fruit: A legume; unilocular; 5–20 cm long; 1–2.5 cm wide; 0.7–1.2 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight to curved; not plicate; asymmetrical; linear; not inflated; compressed; without beak; long tapered at apex to tapered at apex; aligned with longitudinal axis of fruit; long tapered at base to tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; ligneous; seed chambers externally visible, or invisible; margin constricted, or not constricted; margin constricted along both margins to slightly constricted along both margins, or constricted only on 1 margin to slightly constricted only on 1 margin; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 0.6–8 mm long; indehiscent. Replum invisible. Epicarp dull; monochrome; reddish or purple to black brown; with surface texture uniform; glabrous to pubescent and indurate; with hairs erect; with simple hairs; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; rugose; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; flesh when fresh or spongy, or solid; ligneous. Endocarp present; visible; dull; opaque; monochrome; tan; without adhering pieces of testa; septate; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 1–14; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.1–3 mm long; of 1 length only; flattened; straight. Aril absent.
Seed: 5–10 mm long; 3.5–7 mm wide; 1.2–4.5 mm thick; not overgrown; not angular; symmetrical; ovate to oblong; compressed; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; dull; not modified by a bloom; colored; monochrome; reddish brown to black, or olive; glabrous; smooth, or not smooth; with elevated features; rugose; osseous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present; not stated. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible, or fully concealed; concealed by funicular remnant; without faboid split; punctiform; subapical to radicle tip; flush (within depression); not within corona, halo, or rim. Lens not discernible. Endosperm present; thick; not pluglike and not resembling tip of radicle; adnate to embryo. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; with lobes; with lobes not touching; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule glabrous.
Ceratonia siliqua is the carob of commerce. The other species, C. oreothauma, is a "relict species known from two localities in SE Arabia (Oman) and the Horn of Africa (N. Somalia)." Both species are used as animal and human food (Hillcoat et al., 1980)