Parkinsonia L., Sp. Pl. 1: 375. 1753.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/48236F1B-2E6A-0CE8-3318-65DECDAC6D19 |
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scientific name |
Parkinsonia L., Sp. Pl. 1: 375. 1753. |
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Parkinsonia L., Sp. Pl. 1: 375. 1753. View in CoL
Figs 67 View Figure 67 , 68 View Figure 68 , 70 View Figure 70 , 73 View Figure 73
Cercidium Tul., Arch. Mus. Hist. Nat. 4: 133. 1844. Type: Cercidium spinosum Tul. [= Parkinsonia praecox (Ruiz & Pav.) Hawkins]
Rhetinophloeum H. Karst., Fl. Columb. 2: 25. 1862. Type: Rhetinophloeum viride H. Karst. [= Parkinsonia praecox (Ruiz & Pav.) Hawkins]
Peltophoropsis Chiov., Ann. Bot. (Rome) 13(3): 385. 1915. Type: Peltophoropsis scioana Chiov. [≡ Parkinsonia scioana (Chiov.) Brenan]
Cercidiopsis Britton & Rose, N. Amer. Fl. 23(5): 306. 1930. Type: Cercidiopsis microphylla (Torr.) Britton & Rose [≡ Parkinsonia microphylla Torr.]
Type.
Description.
Highly branched shrubs or small trees (Fig. 67F, I View Figure 67 ), most species with green bark (Fig. 67H View Figure 67 ), this sometimes becoming grey-black and shallowly fissured with age; armature extremely variable among species, either unarmed, or armed with stipular spines, axillary thorns (Fig. 67G View Figure 67 ) and in some species additionally with much-reduced spinescent leaf rachides. Stipules either small and caducous or spinescent and persistent. Leaves bipinnate, but sometimes with a highly reduced spinescent rachis and flattened pinnae rachides and then superficially appearing pinnate, pinnae 1-10 pairs, the pinnular rachis winged or cylindrical; leaflets 1-80 (or more) pairs per pinna, oblong, orbicular, elliptic or ovate, oblique, rounded, equilateral or attenuate at the base, acute or mucronate at the apex, usually small and sometimes highly reduced in species with flattened photosynthetic rachides. Inflorescences solitary racemes in leaf axils; pedicels jointed about mid-way along length; bracts deltoid to lanceolate, rapidly deciduous. Flowers usually bisexual (unisexual in P. anacantha ), showy; hypanthium shallowly campanulate, sometimes weakly oblique; sepals 5, free, reflexed, green; petals 5, these auriculate or not, the adaxial petal ovate to orbicular, lateral petals elliptic, ovate or orbicular, yellow, streaked or blotched orange in the centre (Fig. 68D, E View Figure 68 ); stamens 10, free, shorter than petals, anthers oblong or elliptic, dorsifixed, glabrous; pollen in oblate tricolporate monads with moderately reticulate surface ornamentation; ovary linear, glabrous or villous with 5-12 ovules, stigma truncate. Fruits plano-compressed (Fig. 70G, H View Figure 70 ) or turgid and terete (Fig. 70I View Figure 70 ), linear or oblong, straight or weakly falcate, sometimes constricted between the seeds, tardily dehiscent or indehiscent, valves generally papery or thinly coriaceous, 1-8-seeded. Seeds oblong to globose.
Chromosome number.
2 n = 28 ( Goldblatt 1981b).
Included species and geographic distribution.
Twelve species, eight confined to the New World (including two named hybrid species), and four in Africa. Parkinsonia occupies a striking disjunct amphi-Atlantic distribution across arid and semi-arid parts of the New World from the southern USA to Argentina and disjunctly in arid parts of north-eastern and south-western Africa (Fig. 73 View Figure 73 ). One species, P. aculeata (not mapped here) is pantropically cultivated, naturalised and in places invasive (e.g., in northern Australia) and of uncertain regional nativity across its wide New World distribution ( Hawkins et al. 2007).
Ecology.
Parkinsonia is confined to seasonally dry, semi-arid and arid climates, growing in Chaco woodlands, seasonally dry tropical forests, deserts and semi-deserts, occupying most enclaves of the disjunct trans-continental succulent biome distribution (sensu Schrire et al. 2005a; Ringelberg et al. 2020), except south-western Madagascar and the Caatinga in north-eastern Brazil. The true native range of P. aculeata is uncertain but is certainly confined to the New World and hypothesised to be primarily in seasonally inundated, and sometimes saline former lake-bed and river flood-plain habitats often on deeply cracking black vertisols ( Hawkins et al. 2007), i.e., very different habitats from the remaining species.
Etymology.
Named in honour of John Parkinson (1567-1650), the British apothecary and herbalist to King James I of England.
Human uses.
Parkinsonia aculeata is widely cultivated as an ornamental street tree in arid zones.
Notes.
Parkinsonia is robustly supported as sister to the clade comprising Heteroflorum + Conzattia + Delonix + Colvillea (Fig. 66 View Figure 66 ) ( Ringelberg et al. 2022). Until recently some species were referred to the genus Cercidium , but it is now clear that Cercidium is phylogenetically nested within Parkinsonia ( Haston et al. 2005) and new name combinations for all species are now available in Parkinsonia ( Romão and Mansano 2021). In the New World, Parkinsonia species are frequently referred to as Palo Verdes, because of their characteristic green bark.
Taxonomic references.
Brenan (1980) with illustration; Carter (1974); Hawkins et al. (2007); Karsten (1862) with illustration; Romão and Mansano (2021) with illustrations.
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