| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Humboldtia Vahl.

Batschia Vahl, Humboldia Reichb.

Type species: H. laurifolia Vahl.

Habit and leaf form. Shrubs; unarmed.

Phyllotaxy spiral. The leaves large, compound; pinnate; paripinnate. The leaflets leathery and venulose, few per leaf (with the proximal pair smaller); opposite or sub-opposite; petiolulate to sessile to sub-sessile; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’; without a continuous marginal nerve. Stipules present, persistent and conspicuous in mature leaves (with a recurved spur); leafy. Stipels absent.

Inflorescence and floral morphology. The inflorescences axillary and terminal (at shoot apices or at older nodes); unbranched; dense, reflexing simple racemes. The flowers not distichous. Bracts absent at anthesis, or persistent beyond anthesis. Bracteoles present; coloured, relatively large and enclosing the flower buds (spreading later); persistent beyond anthesis; valvate.

The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx, or in the calyx and in the corolla; coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; turbinate or shortly tubular. The perianth comprising distinct calyx and corolla. Calyx 4; not covering the rest of the flower in bud; polysepalous; coloured, more or less regular to markedly irregular (the sepals subequal); members imbricate. Corolla present; slightly irregular, or very irregular; 5 (with subequal petals), or 3 (the lower petals sometimes reduced or absent); including greatly reduced members (representing the lower ones), or without greatly reduced members; polypetalous. Petals clawed, or sessile; imbricate; imbricate-ascending; white, or yellow, or red. Disk absent. The androecium comprising 10 members; members all free of one another; members markedly unequal (alternating longer and shorter); including staminodia. The staminodia 5; tooth-like and shorter than the fertile stamens. Fertile stamens alternating with staminodes, 5. Anthers attached well above the base of the connective. Ovary stipitate; eccentric, with the stipe adnate (the style filiform). Stigma dilated (clavate-capitate on the filiform style), or not dilated. Ovules few.

Fruit, seed and seedling. Fruit a two-valved pod; straight, or curved (oblong, oblique or falcate); without markedly twisting or enrolling valves; compressed, leathery, not becoming woody. Seeds non-endospermic; not arillate; with a straight or slightly oblique radicle; amyloid-positive. Cotyledons of Type 4; with a vascular system in one plane.

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 common (the veins transcurrent), or 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. 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; (at least some of them) thin-walled; hair feet (at least some of them) complex with vertical walls. Basally bent hairs absent. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not 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; not conspicuously pitted in optical section; staining normally with safranin; thin.

Wood anatomy. Intervascular pits very small.

Pollen ultrastructure. Tectum reticulate; rugulose reticulate. Length of colpi greater than one half pole to pole distance.

Species number and distribution. 9 species. India, Ceylon.

Tribe. Detarieae (Amherstieae of Cowan and Polhill 1981); Amherstieae clade of Bruneau et al. (2008).

Comments. Widely cultivated.

Miscellaneous. Illustrations: • Humboldta laurifolia: Wight, Ic. Pl. Ind. Orient. (1850). • H. brunonis: Wight, Ic. Pl. Ind. Orient. (1850). • H. vahliana: Wight, Ic. Pl. Ind. Orient. (1850). • H. laurifolia (as Batschia): Nat. Pflanzenfam. III (1894).

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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