Harrisonia A.Juss.

Scientific Description

Family Simaroubaceae.

Habit and leaf form. Small trees, or shrubs. Leaves cauline. Stem internodes solid. Mesophytic. Leaves alternate (clustered sometimes); spiral; petiolate; non-sheathing; not gland-dotted; compound; ternate (trifoliate); imparipinnate. Leaflets elliptic to ovate. Leaf blades pinnately veined; cross-venulate. Leaves with stipules, or without stipules (sometimes). Stipules when present, intrapetiolar; spiny (or conical or somewhat recurved); caducous. Leaf blade margins entire, or serrate (irregularly). Leaves without a persistent basal meristem. Leaf anatomy. Hairs present. Extra-floral nectaries absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary; cymes few-flowered. Flowers sessile; bracteate; ebracteolate; small; regular; 4 merous, or 5 merous; cyclic; pentacyclic. Floral receptacle developing an androphore, or developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present; extrastaminal. Perianth with distinct calyx and corolla; 8, or 10; 2 -whorled; isomerous. Calyx present; 4–5; 1 -whorled; gamosepalous; blunt-lobed; imbricate, or valvate; regular. Calyx lobes triangular. Corolla present; 4–5; 1 -whorled; polypetalous; imbricate (slightly); regular; green (green-white), or yellow. Petals more or less elliptic, or ovate to oblong. Corolla members minutely ciliolate. Androecial members definite in number. Androecium 8, or 10. Androecial members free of the perianth; all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 8, or 10; all more or less similar in shape; diplostemonous; oppositisepalous. Filaments appendiculate. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 4–5 carpelled. The pistil 5 celled, or 5 celled. Carpels isomerous with the perianth, or increased in number relative to the perianth. Gynoecium syncarpous; synovarious to eu-syncarpous; superior. Ovary plurilocular; 4 locular, or 5 locular. Gynoecium stylate. Styles 4–5; free, or partially joined; lateral, or ‘gynobasic’. Placentation axile. Ovules 1 per locule; pendulous; epitropous; with ventral raphe (the micropyle superior); hemianatropous to anatropous.

Fruit and seed features. Fruit fleshy (K), or non-fleshy (K); an aggregate, or not an aggregate; indehiscent, or a schizocarp. Mericarps if schizocarpic comprising drupelets. Fruit when not schizacarpous, a drupe. Gynoecia of adjoining flowers combining to form a multiple fruit (A). Fruit 2–5 seeded (pyrenes). Seeds more or less non-endospermic. Cotyledons 2 (large, expanded). Embryo straight, or curved.

Etymology. After Charles Harrison who wrote a book on fruit trees, published in 1825.