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The families of flowering plants

L. Watson and M.J. Dallwitz

Picramniaceae (Engl.) Fernando & Quinn

~ Simaroubaceae.

Habit and leaf form. Trees, or shrubs; non-laticiferous. Leaves alternate; petiolate; non-sheathing; not gland-dotted; without marked odour; compound; pinnate. Lamina pinnately veined; cross-venulate. Leaves exstipulate.

Leaf anatomy. The leaf lamina dorsiventral. Extra-floral nectaries present (abaxially on the lamina). Abaxial epidermis papillose, or not papillose. Mucilaginous epidermis present, or absent. Stomata mainly confined to one surface (abaxial); anomocytic. Hairs present; eglandular and glandular. Adaxial hypodermis absent. The mesophyll without etherial oil cells (?); not containing mucilage cells; with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts; containing crystals. The crystals druses and solitary-prismatic (and styloids in Alvaradoa).

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Secondary thickening developing from a conventional cambial ring.

The vessel end-walls simple. The axial xylem with fibre tracheids.

Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Plants dioecious. Female flowers with staminodes, or without staminodes. Gynoecium of male flowers pistillodial, or vestigial, or absent.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in panicles. Inflorescences terminal, or axillary, or cauliflorous. Flowers minute, or small; regular; 3–5(–6) merous. Free hypanthium absent.

Perianth with distinct calyx and corolla, or sepaline (male flowers sometimes lacking petals); 3–10(–12); 1 whorled, or 2 whorled; isomerous (when petals lacking), or anisomerous. Calyx 3–5(–6); 1 whorled; gamosepalous. Calyx lobes markedly longer than the tube. Calyx regular; imbricate, or valvate. Corolla when present, 3–5(–6) (sometimes absent from male flowers, reduced in female flowers); 1 whorled; imbricate; regular.

Androecium in male flowers, 3–5(–6). Androecial members free of the perianth; free of one another; 1 whorled. Androecium of male flowers exclusively of fertile stamens. Stamens 3–5(–6); isomerous with the perianth; alternisepalous; opposite the corolla members. Anthers versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with more than one middle layer (2 or 3). Pollen grains aperturate; 3 aperturate; colporate; 2-celled.

Gynoecium 2–3 carpelled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. The pistil 1–3 celled. Gynoecium syncarpous; synovarious, or synstylovarious, or eu-syncarpous (?); superior. Ovary 1–3 locular. Gynoecium non-stylate to stylate. Styles shorter than the ovary. Placentation in Picramnia, axile to apical, or basal to axile (Alvaradoa). Ovules in the single cavity when unilocular, 2; 2 per locule; pendulous (when apical), or ascending (when basal); apotropous (Alvaradoa), or epitropous (Picramnia); hemianatropous, or anatropous (?); bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Hypostase present. Endosperm formation nuclear. Endosperm haustoria present; chalazal. Embryogeny onagrad.

Fruit fleshy, or non-fleshy; indehiscent; a berry (Picramnia), or capsular-indehiscent and a samara (Alvaradoa). Seeds non-endospermic. Cotyledons 2. Embryo straight, or curved (?).

Physiology, phytochemistry. Anthraquinones detected (Alvaradoa, Picramnia); polyacetate derived.

Geography, cytology. Neotropical. Central and tropical America, West Indies.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Rutales. Cronquist’s Subclass Rosidae; Sapindales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Picramniales.

Species about 50. Genera 2; Alvaradoa, Picramnia.

General remarks. See Fernando and Quinn (1995). Note that satisfactory representation of recent notions on the proper dispositions of genera previously referred to Simaroubaceae will necessitate thorough overhaul of the descriptions presented in this package (cf. Irvingiaceae, Kirkiaceae, Simaroubaceae, Surianaceae, Stylobasiaceae). It is very easy to publish taxonomic realignments with or without supposedly ‘diagnostic circumscriptions’, but harder to attend to the practical requirement for fully workable comparative descriptions.

Illustrations. • Picramnia nitida, P. sellowii and P. warmingiana: Nat. Pflanzenfam. III (1887). • Picramnia latifolia, as P. umbrosa: Seeman, Fitch & Hooker, Herald voyage (1852). • Leaf hairs of Picramnia coccinea, with abaxial leaf epidermis of Rigiostachys (= Recchia) bracteata and axial hairs of Eurycoma longifolia (Solereder, 1908).

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: 5th March 2018.’.