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The families of flowering plants

L. Watson and M.J. Dallwitz

Santalaceae R. Br

Including Anthoboleae (Anthobolaceae) Dum., Arionaceae Van Tiegh., Arjonaceae Van Tiegh. corr. Bullock, Canoppiaceae (Canopodaceae) C. Presl, Exocarpaceae Gagnep., Osyrinae (Osyridaceae) Link, Podospermaceae Dulac, Sarcopodaceae Gagnep.; excluding Viscaceae.

Habit and leaf form. Trees, shrubs, and herbs. More or less ‘normal’ plants, or switch-plants; sometimes with the principal photosynthesizing function transferred to stems. Leaves well developed to much reduced. Plants with roots, or rootless (?); parasitic; haustorially parasitic; green and photosynthesizing; parasitic on roots of the host, or on aerial parts of the host. Mesophytic, or xerophytic. Leaves opposite (usually), or alternate; ‘herbaceous’, or leathery, or fleshy, or membranous, or modified into spines; petiolate to sessile; gland-dotted, or not gland-dotted; aromatic, or without marked odour; simple; pulvinate. Lamina entire; one-veined, or pinnately veined. Leaves exstipulate.

Leaf anatomy. The leaf lamina dorsiventral, or bifacial, or centric. Stomata present; usually paracytic. Adaxial hypodermis present, or absent. Minor leaf veins without phloem transfer cells (Colpoön).

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

The vessel end-walls simple. The vessels without vestured pits. The axial xylem with tracheids; often with vasicentric tracheids; with fibre tracheids. The parenchyma apotracheal, or paratracheal.

Reproductive type, pollination. Plants hermaphrodite, or monoecious, or dioecious.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in racemes, or in spikes, or in heads, or in fascicles. The ultimate inflorescence units cymose, or racemose. Inflorescences terminal, or axillary; variously spikes, racemes or heads, the flowers solitary in the bract axils or forming cymes of three. Flowers bracteate; small; regular; (3–)4–5(–8) merous; cyclic; tricyclic. Free hypanthium present, or absent.

Perianth sepaline, or petaline (dubiously, then perhaps sepaline-petaloid); (3–)4–5(–8); free, or joined (the lobes valvate); 1 whorled; sepaloid, or petaloid; green, or white, or cream, or yellow, or red; fleshy, or non-fleshy; persistent, or deciduous. Calyx (‘calycode’) (3–)4–5(–8); 1 whorled; gamosepalous; regular; fleshy, or non-fleshy; persistent, or not persistent; valvate.

Androecium (3–)4–5(–8). Androecial members free of the perianth (attached at its base), or adnate (to the middle of the lobes); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (3–)4–5(–8); isomerous with the perianth; oppositisepalous. Anthers dorsifixed, or basifixed; dehiscing via pores, or dehiscing via short slits to dehiscing via longitudinal slits; introrse; bilocular, or four locular (Choretrum); tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer, or initially with more than one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colpate, or porate, or colporate (or colporoidate); 2-celled (in 4 genera).

Gynoecium (2–)3(–5) carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 1 celled, or (2–)3(–5) celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; partly inferior to inferior. Ovary 1 locular (at least above). Epigynous disk commonly present. Gynoecium non-stylate, or non-stylate to stylate, or stylate. Styles 1; apical. Stigmas 1; capitate (or lobed). Placentation basal, or free central. Ovules differentiated to not differentiated; in the single cavity 1–3(–4); pendulous; hemianatropous to anatropous; unitegmic, or without integuments; tenuinucellate. Embryo-sac development Polygonum-type, or Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 1 (trinucleate, Quinchamalium), or 3 (usually); not proliferating; ephemeral. Synergids usually hooked. Endosperm formation cellular, or helobial. Endosperm haustoria present; chalazal, or lateral. Embryogeny variable and often irregular.

Fruit fleshy, or non-fleshy; indehiscent; a drupe, or a nut. The drupes with one stone. Fruit 1 seeded. Seeds endospermic. Endosperm oily, or not oily. Seeds without a testa. Cotyledons 2. Embryo achlorophyllous (Thesium linifolium).

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Comandra. Anatomy non-C4 type (Comandra). Sugars transported as sucrose (in Santalum). Not cyanogenic. Polyacetylenes recorded. Alkaloids present, or absent. Iridoids not detected. Saponins/sapogenins absent. Proanthocyanidins present (Gibbs 1974), or absent. Ellagic acid absent (Thesium).

Geography, cytology. Temperate to tropical. Cosmopolitan, except in cold regions. X = 5–7, 12, 13 (or more).

Taxonomy. Subclass Dicotyledonae; dubiously Crassinucelli. Dahlgren’s Superorder Santaliflorae; Santalales. Cronquist’s Subclass Rosidae; Santalales. APG III core angiosperms; core eudicot; Superorder Santalanae. APG IV Order Santalales.

Species 400. Genera 38; Acanthosyris, Amphorogyne, Antholobus, Arjona, Austroamericium, Buckleya, Cervantesia, Choretrum, Cladomyza, Colpoon, Comandra, Daenikera, Dendromyza, Dendrotrophe, Dufrenoya, Elaphanthera, Exocarpos, Geocaulon, Jodina, Kunkeliella, Leptomeria, Mida, Myoschilos, Nanodea, Nestronia, Okoubaka, Omphacomeria, Osyridocarpos, Osyris, Phacellaria, Pyrularia, Quinchamalium, Rhoiacarpos, Santalum, Scleropyrum, Spirogardnera, Thesidium, Thesium.

Economic uses, etc. Some produce edible fruit, and Santalum album is the source of timber and perfume (sandalwood and sandalwood oil).

Illustrations. • Le Maout and Decaisne: Osyris alba, Santalum. • Osyris tenuifolia: Thonner. • Le Maout and Decaisne: Thesium, Myoschylos. • Exocarpos bidwillii: Hooker, Fl. Novae-Zelandiae (1853). • Osyridocarpos schimperianus: Hook Ic. Pl. 15 (1883). • Phacellaria rigidula: Hook. Ic. Pl. 14 (1880–82). • Thesium humifusum (B. Ent.). • Thesium humifusum: Eng. Bot. 1248, 1868. • Thesium costatum and T. lacinulatum: Hook. Ic. Pl. 31 (1915).

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: 15th April 2018.’.