| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Pterolobium Wight & Arn.

Kantuffa Roth, Quartinia A. Rich., Reichardia Roth

Type species: P. stellatum (Forssk.) Brenan.

Habit and leaf form. Trees, or shrubs, or climbers or scramblers; without tendrils; without specialized ‘short shoots’; armed (with recurved prickles on branchlets and rachides).

Phyllotaxy spiral. The leaves compound; bipinnate (terminating in a pair of pinnae); with opposite or sub-opposite leaflets; with rachides adaxially ridged. The leaflets small, many per leaf; sessile to sub-sessile; markedly asymmetrical to symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipules aculeate, absent or early caducous or very inconspicuous in mature leaves; membranous. Stipels present (rarely), or absent.

Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; panicles (of racemes). The flowers not distichous. Bracts very caducous, absent at anthesis. Bracteoles absent; absent at anthesis.

The flowers rather small; hermaphrodite; pentamerous; white or green. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; short. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud; polysepalous; markedly irregular (the lowermost member concave and larger); members imbricate. Corolla present; slightly irregular (the petals slightly unequal); 5; without greatly reduced members; polypetalous. Petals clawed, or sessile; imbricate; imbricate-ascending; white, or yellow. The androecium comprising 10 members; declinate to not declinate; members all free of one another (the filaments sometimes basally villous); members all more or less equal in length to markedly unequal; comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing introrsely. Ovary sessile or subsessile; free (asymmetrical). Stigma lobed and somewhat dilated. Ovules solitary.

Fruit, seed and seedling. Fruit samaroid, red, indehiscent; winged distally to the single seed (with an oblique or falcate, distal wing). Seeds non-endospermic; with a straight or slightly oblique radicle; amyloid-negative.

Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses common in the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders absent. Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids.

Abaxial: Abaxial interveinal epidermal cell walls scarcely staining with safranin.

Pollen ultrastructure. Tectum reticulate; finely to moderately regularly reticulate. Length of colpi greater than one half pole to pole distance (with a margocolpus). Foot layer of pollen wall with obvious projections.

Cytology. Basic chromosome number, x = 12. 2n = 24.

Species number and distribution. 11 species. Tropical Africa, Asia, Australia.

Tribe. Caesalpinieae.

Comments. Widely cultivated.

Miscellaneous. Illustrations: • Pterolobium densiflorum and P. membranulaceum: Ding Hou, Fl. Malesiana 12 (1995). • Pterolobium lacerans: Wight, Ic. Pl. Ind. Orient. (1850).

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: 4th August 2019. delta-intkey.com’.

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