The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: H. balansae M. Micheli.
Habit and leaf form. Shrubs; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; paripinnate. The leaflets oblong, leathery, dentate, many per leaf; opposite or sub-opposite, or alternate; petiolulate; without noticeably twisted petiolules; with sub-parallel nerves. Stipules absent or early caducous or very inconspicuous in mature leaves (minute); membranous. Stipels present.
Inflorescence and floral morphology. The inflorescences axillary; unbranched; short simple racemes. The flowers not distichous. Bracts small, persistent beyond anthesis. Bracteoles present; small, not enclosing the flower buds; persistent beyond anthesis.
The flowers small; hermaphrodite; not papilionaceous; not pentamerous throughout; departing from pentamery in the calyx, or in the calyx and in the androecium; coloured. Hypanthium present. The perianth comprising distinct calyx and corolla. Calyx present; covering the rest of the flower in bud; Swartzieae type (closed before flowering, splitting more or less irregularly into valvate lobes or teeth); gamosepalous (comprising the obconic, unsegmented, more or less truncate tube). Corolla present; regular (?); 5; without greatly reduced members; polypetalous (the petals caducous). Petals linear or spathulate, sessile; imbricate; imbricate-descending with the posterior petal (vexillum) outside; white. The androecium comprising 10–12 members; members all free of one another; members all more or less equal in length; comprising only fertile stamens. Fertile stamens 10–12. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary with a very short style, stipitate; free. Stigma small. Ovules pendulous, few (4–5).
Fruit, seed and seedling. Fruit a two-valved pod; straight; ovoid, turgid, thick and succulent, not becoming woody. Seeds non-endospermic; not arillate; with an inflexed radicle; amyloid-negative; with starch.
Transverse section of lamina. Leaves without 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 present; prisms. Simple unbranched hairs common; smooth. 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 absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; not conspicuously pitted; thin. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (actinocytic & cyclocytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; staining normally with safranin; thin.
Wood anatomy. Wood without septate fibres; storied. Intervascular pits very small.
Pollen ultrastructure. Tectum punctate; smooth punctate, or puncticulate. Length of colpi greater than one half pole to pole distance.
Cytology. Basic chromosome number, x = 11. 2n = 22.
Species number and distribution. 1 species (H. balansae). South America.
Tribe. Papilionoideae-Exostyleae (former Swartzieae) (but cf. Sophoreae).
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’.