The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: L. cassioides Gaudich.
Habit and leaf form. Xeromorphic shrubs; unarmed.
Phyllotaxy distichous. The leaves ostensibly ostensibly simple, or compound (being trifoliolate, or 1-foliolate by reduction to the terminal leaflet); when ostensibly simple, pinnately veined with a predominant midrib; commonly more or less pinnate (i.e., when trifoliolate); if interpreted as pinnate, imparipinnate. The leaflets few per leaf (1 or 3, mucronate with thickened margins); symmetrical or nearly so; pinnately veined, with a predominant midrib. Stipules present, persistent and conspicuous in mature leaves; membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary; unbranched; short, loose, sometimes few-flowered simple racemes. The flowers distichous. Bracts small, caducous, absent at anthesis. Bracteoles absent; absent at anthesis.
The flowers hermaphrodite; not pentamerous throughout (4 or 5 merous); departing from pentamery in the androecium, or in the calyx, in the corolla, and in the androecium; coloured. Calyx 4–5; covering the rest of the flower in bud; more or less polysepalous; more or less regular (the sepals only slightly unequal, the the inner two smaller and thinner than the outer two); members imbricate. Corolla present; slightly irregular; 4–5; without greatly reduced members; polypetalous. Petals imbricate; imbricate-ascending; spreading, yellow, or yellow and red. The androecium comprising 2 members; members all more or less equal in length, or markedly unequal; comprising only fertile stamens. Fertile stamens 2 (on one side of the gynoecium, opposite the adaxial sepals). Anthers linear, attached at the base of the connective; dehiscing via pores or short slits. Ovary sericeous, shortly stipitate, or sessile or subsessile; free (the style filiform). Stigma not dilated (terminal, on the curved, glabrous style). Ovules few (2 or 3).
Fruit, seed and seedling. Fruit a two-valved pod; more or less flat, obliquely oblong and almost glabrous; valves twisting and enrolling during dehiscence; not becoming woody. Seeds endospermic; compressed, ellipsoid, arillate (the aril small and fleshy); with a straight or slightly oblique radicle; amyloid-negative.
Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Adaxial hypodermis absent. Leaf girders common (the veins transcurrent). 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; smooth. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs present. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; thin. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (mixed anisocytic, tetracytic, anomcytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section; staining normally with safranin; thin.
Pollen ultrastructure. Tectum reticulate; rugulose reticulate. Length of colpi greater than one half pole to pole distance.
Cytology. Basic chromosome number, x = 14. 2n = 28.
Species number and distribution. About 14 species. Australia.
Comments. Widely cultivated.
Miscellaneous. Illustrations: • L. lanceolata: Bot. Mag. 110 (1884). • L. punctata, e.m. scanned pollen (Graham & Barker, 1981).
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’.