The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: P. riedelii Tul.
Habit and leaf form. Tall trees; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; paripinnate. The leaflets many per leaf; ovate, opposite or sub-opposite; sessile to sub-sessile; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant midrib. Stipules conspicuous or inconspicuous, present, persistent and conspicuous in mature leaves, or absent or early caducous or very inconspicuous in mature leaves. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary (short, often fasciculate at the nodes of leafless, year-old branches); unbranched, or branched; of racemose units; simple racemes, or fascicles. The flowers not distichous. Bracts very caducous, absent at anthesis. Bracteoles present; small, not enclosing the flower buds; very caducous, absent at anthesis; not valvate; free.
The flowers showy; hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx and in the corolla; coloured. Hypanthium more or less absent, the androecium hypogynous. The perianth comprising distinct calyx and corolla. Calyx 4; covering the rest of the flower in bud; polysepalous; more or less regular (the sepals subequal); members imbricate. Corolla present; very irregular; 3; without greatly reduced members; polypetalous. Petals sessile; obovate, all similar, imbricate; red. Disk absent. The androecium comprising 10 members; more or less; with united members (all connate into a sheath, this split on upper side and with the filaments free only at its top); comprising only fertile stamens. Fertile stamens 10. Anthers ovate, uniform, attached well above the base of the connective. Ovary stipitate; free. Stigma lobed and somewhat dilated (the style long and filiform). Ovules few.
Fruit, seed and seedling. Fruit indehiscent; oblong, curved (subfalcate); winged longitudinally; 1 winged (on the upper suture); compressed, thin, not becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation reticulate, not predominantly longitudinal. Seeds non-endospermic; with a straight or slightly oblique radicle; amyloid-positive.
Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders absent. Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres.
Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially. Simple unbranched hairs common; scabrid. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet present; hair feet all simple, without vertical walls. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; conspicuously pitted; thin. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; conspicuously pitted in optical section; staining normally with safranin; thin.
Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance.
Cytology. Basic chromosome number, x = 11. 2n = 22.
Species number and distribution. 2 species (P. riedelii and P. septentrionalis). Central and tropical South America.
Miscellaneous. Illustrations: • P. riedelii: Fl. Brasiliensis 15 (1870).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classification. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1993 onwards. The genera of Leguminosae-Caesalpinioideae and Swartzieae: descriptions, illustrations, identification, and information retrieval. In English and French. Version: 22nd March 2017. delta-intkey.com/caes’.