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The families of flowering plants

L. Watson and M.J. Dallwitz

Julianiaceae Hemsl.

~ Anacardiaceae.

Habit and leaf form. Small trees, or shrubs; resinous (assuming that ‘milky juice’ is not latex). Often with terminal aggregations of leaves. Leaves deciduous; alternate; spiral; petiolate; non-sheathing; compound; pinnate. Lamina pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins of the leaflets serrate.

Leaf anatomy. The leaf lamina usually dorsiventral. Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present (often forming a dense covering on both leaf surfaces); eglandular, or glandular (the latter always present, variously shaped); unicellular and multicellular. Adaxial hypodermis absent. Lamina with secretory cavities (in the phloem). Secretory cavities containing resin (the juice supposedly not latex, though ‘milky’); schizogenous. The mesophyll containing crystals. The crystals exclusively druses.

Axial (stem, wood) anatomy. Secretory cavities present (in cortex, phloem and pith); with resin (with thick, milky juice). Cork cambium present; initially superficial. Nodes tri-lacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays mixed wide and narrow.

The wood diffuse porous. The vessels small; solitary, radially paired, in radial multiples, and clustered. The vessel end-walls simple, or simple and reticulately perforated. The vessels without vestured pits. The axial xylem without fibre tracheids; with libriform fibres; at least sometimes including septate fibres. The fibres without spiral thickening. The parenchyma scanty paratracheal. ‘Included’ phloem absent. The wood not storied. Tyloses present (abundant).

Reproductive type, pollination. Plants dioecious. Female flowers without staminodes. Gynoecium of male flowers absent. Floral nectaries absent.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes (female), or in panicles (male). The ultimate inflorescence units cymose. Inflorescences of female plants consisting of small, 3–4 flowered dichasia, those of male plants in the form of many-flowered panicles; with involucral bracts (female), or without involucral bracts (male); pseudanthial (female plants), or not pseudanthial (male plants). Flowers small; regular; cyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth sepaline (male flowers), or absent (female flowers); of male flowers, 3–8; 1 whorled. Calyx of male flowers, 3–8; 1 whorled; gamosepalous; 3–8 blunt-lobed; regular.

Androecium of male flowers, 3–8. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 3–8; isomerous with the perianth; alternisepalous. Anthers basifixed (to slightly ventrifixed); versatile; dehiscing via longitudinal slits; extrorse; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; (3–)5–8 aperturate; colporate (Juliania), or rugate (Orthopterygium).

Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 1 locular; sessile. Gynoecium stylate. Styles 3 (the style tripartite, with flattened branches); partially joined; apical. Stigmas 3. Placentation basal. Ovules in the single cavity 1; ascending; with a placental obturator; hemianatropous; unitegmic; crassinucellate (?).

Fruit non-fleshy; indehiscent; a nut. Gynoecia of adjoining flowers combining to form a multiple fruit (the accrescent, thickened, subglobose involucre containing 1–2 hairy nuts more or less adnate to its wall). Seeds non-endospermic. Cotyledons flat. Embryo curved, or bent (?). The radicle lateral.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Not cyanogenic. Alkaloids absent (2 species). Saponins/sapogenins present. Proanthocyanidins present. Ellagic acid absent.

Geography, cytology. Neotropical. Sub-tropical to tropical. Central America, Peru.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Sapindales. Cronquist’s Subclass Rosidae; Sapindales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Sapindales (as a synonym of Anacardiaceae).

Species 5. Genera 2; Amphipterygium (Juliania), Orthopterygium.

General remarks. Seemingly separable from Anacardiaceae sensu stricto (q.v.) by the serrate lamina, cymose inflorescence, no hypogynous disk, and alternisepalous stamens with extrorse anthers, hemianatropous ovules, and nuts in multiple fruits (floral morphological comparisons being much complicated by dioecism and monoecism).

Illustrations. • Amphipterygium adstringens (as Juliania): Hook. Ic. Pl. 28 (1905). • Technical details: Amphipterygium (as Juliania): Hutchinson.

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, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 13th March 2017.’.