Parkinsonia

Taxonomy

Parkinsonia C. Linnaeus Sp. Pl. 375. 1 Mai 1753.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.1.20.
Tribe: Caesalpinieae.
Group: Peltophorum.
Species Studied - Species in Genus: 11 studied; 15 in genus.

Description

Fruit: A legume; unilocular; 2.5–15 cm long; 0.5–2.5 cm wide; 0.5 cm thick; 2–9 times longer than wide to more than 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; not twisted; asymmetrical; elliptic to oblong, or moniliform; not inflated; flattened to terete; without beak; long tapered at apex to tapered at apex; aligned with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous to coriaceous; seed chambers externally visible; margin constricted, or not constricted; margin constricted along both margins to slightly constricted along both margins; margin without sulcus; margin plain; wing(s) absent; stipitate to substipitate; with the stipe 6–20 mm long; with all layers dehiscing to indehiscent; splitting along suture(s). Replum invisible. Epicarp dull; monochrome; brown (reddish to tan); with surface texture uniform; glabrous to pubescent and indurate; with hairs erect; eglandular; without spines; not smooth; with elevated features; veined; longitudinally veined relative to fruit length; not tuberculate; striate; exfoliating (in strips); without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; with fibers; without reniform canals; spongy; coriaceous to chartaceous. Endocarp present; visible; dull to glossy; opaque; monochrome; tan (golden to silvery); without adhering pieces of testa; nonseptate; exfoliating (?); remaining fused to mesocarp and epicarp; entire. Seed(s) 1–10; length parallel with fruit length, or oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.1–5 mm long; of 1 length only; filiform (with broad base); straight, or plicate. Aril absent.

Seed: 5–12 mm long; 4–7 mm wide; 2–5 mm thick; not overgrown; not angular; symmetrical; elliptic to oblong; compressed (to subterete); 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; glossy to dull; not modified by a bloom; colored; monochrome, or mottled; brown, or olive, or red (orange mottled with brown streak); with tan overlay, or brown overlay; glabrous; smooth; osseous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present; concentric. Rim absent. Wing(s) absent. Raphe visible (faint from hilum to base). Hilum present; visible, or fully concealed; concealed by funicular remnant; without faboid split; punctiform (difficult to locate); apical at apex of radicle tip to subapical to radicle tip; flush; not within corona, halo, or rim. Lens discernible; 0.1–0.5 mm long; with margins straight, or curved; wedge-shaped; nearly circular to elliptic; not in groove of raphe; mounded to flush; similar color as testa, or dissimilar color from testa (?); lighter than testa, or darker than testa (?); black, or yellow (sometimes with tan center or black border); not within corona, halo, or rim. Endosperm present; thick; not pluglike and not resembling tip of radicle; adnate to testa 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 touching (auriculate), or not touching; without basal groin formed by lobes; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule rudimentary to well developed; glabrous.

Distribution

Generic Notes

Isely (1975) summarized the history of the generic delimitation discussions of Parkinsonia and Cercidium and concluded that "the differences among the constituent species of Parkinsonia are not sufficiently great to merit generic segregation." This conclusion was supported by Polhill and Vidal (1981). Carter (1974) monographed Cercidium, using both fruit and seed characters to circumscribe the species. On the other hand, seed and fruit characters support the concept of one genus, Parkinsonia. Watson and Dallwitz (1983) erroneously reported that some fruits are "conspicuously winged". Polhill (1994b) did not list Cercidium in his latest legume classification, so it must assumed that he continued to synonymize Cercidium under this genus. Lersten and Curtis (1995) surveyed the foliar idioblasts of Parhinsonia, s.s., and Cercidium. The idioblasts of Parkinsonia are adaxially and abaxially dimorphic, and Cercidium has veinlet idioblasts, a new type known only from Cercidium. They concluded that idioblast anatomy supports maintaing the two genera separately.