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The families of flowering plants

L. Watson and M.J. Dallwitz

Loranthaceae Juss.

Including Dendrophthoaceae Van Tiegh., Dendrophthoraceae Dostál, Elytranthaceae Van Tiegh., Gaiadendraceae Van Tiegh., Lepidariaceae Van Tiegh., Nuytsiaceae Van Tiegh., Porosectaceae Dulac, Psittacanthaceae Nak., Treubaniaceae Van Tiegh., Treubellaceae Van Tiegh.; excluding Eremolepidaceae.

Habit and leaf form. Shrubs (mostly, or ‘shrublets’), or trees (e.g., well grown specimens of Nuytsia), or lianas (a few). ‘Normal’ plants, or switch-plants (occasionally); switch forms with the principal photosynthesizing function transferred to stems. Leaves well developed, or much reduced (rarely). Plants rootless (in the normal sense), or with roots (but with haustoria rather than root-hairs, e.g. Nuytsia?); more or less succulent (in Nuytsia), or non-succulent; parasitic; haustorially parasitic; green and photosynthesizing (evergreen branch parasites (mistletoes), parasitic vines and a few parasitic trees and shrubs, with haustoria which often induce gall-like growth on the host); parasitic on aerial parts of the host (mostly), or on roots of the host (a few, with Nuytsia said to parasitize the roots of grasses). Stem growth conspicuously sympodial. Mesophytic, or xerophytic. Leaves persistent; usually opposite; leathery (usually), or fleshy, or membranous (rarely); borne edgewise to the stem, or ‘normally orientated’; simple. Lamina entire; one-veined, or pinnately veined, or parallel-veined. Leaves exstipulate. Lamina margins entire. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral, or bifacial (or the lamina mainly comprising isodiametric cells). Stomata mainly confined to one surface (abaxial, on dorsiventral leaves), or on both surfaces (or all round, on leaves with isobilateral or homogeneous structure); often paracytic (usually not sunken). Hairs present, or absent (generally infrequent, but when present somewhat complex); seemingly exclusively eglandular; when present, multicellular. Multicellular hairs generally more or less branched (ranging from uniseriate with small lateral processes arising at the distal ends of the cells to candelabra forms). Complex hairs present, or absent; sometimes stellate. Lamina with secretory cavities, or without secretory cavities. Secretory cavities in Nuytsia containing mucilage. The mesophyll with sclerenchymatous idioblasts, or without sclerenchymatous idioblasts; containing crystals. The crystals druses and solitary-prismatic.

Axial (stem, wood) anatomy. Secretory cavities present (in Nuytsia), or absent; with mucilage. Cork cambium present (usually), or absent; when present, initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles to comprising a ring of bundles, or comprising two or more rings of bundles; collateral (usually), or bicollateral. Internal phloem absent (usually), or present (in young branches of Nuytsia). Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring, or anomalous. The anomalous secondary thickening when present, via concentric cambia (Nuytsia). Primary medullary rays wide to narrow.

The vessels small (sometimes extremely so); very variable in arrangement. The vessel end-walls simple. The vessels with spiral thickening, or without spiral thickening. The axial xylem with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres. The parenchyma apotracheal, or apotracheal and paratracheal (typically predominantly apotracheal). ‘Included’ phloem absent. The wood partially storied (VPI).

Reproductive type, pollination. Plants hermaphrodite (nearly always), or monoecious (Nuytsia, where the central flower of each triplet is female, the laterals male). Pollination entomophilous, or ornithophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, in racemes, in spikes, in fascicles, and in umbels. The ultimate inflorescence units cymose (the flowers often in threes). Inflorescences dichasial, the dichasia sometimes resembling racemes, spikes, umbels etc.. Flowers bracteolate (the two bracteoles adnate to form a ‘calyculus’ external to the calyx); regular to somewhat irregular. The floral irregularity involving the perianth. Flowers cyclic; tetracyclic. Floral receptacle markedly hollowed. Free hypanthium absent.

Perianth with distinct calyx and corolla, or petaline (the calyx much reduced, often to a mere rim), or absent (sometimes, in Amyema?); 3–9; 2 whorled, or 1 whorled (with the calyx obsolete). Calyx 1 whorled; gamosepalous (reduced to a lobed or toothed cup or rim); entire, or lobulate, or blunt-lobed, or toothed; regular; persistent; open in bud. Corolla (3–)5–6(–9); 1 whorled; polypetalous, or gamopetalous; valvate; often tubular (the tube often bent and split down one side); unequal but not bilabiate, or bilabiate, or regular; often yellow, or orange, or red.

Androecium (3–)5–6(–9) (as many as C). Androecial members adnate (to the corolla); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (3–)5–6(–9); isomerous with the perianth; alternisepalous; opposite the corolla members. Anthers dehiscing via longitudinal slits; introrse; bisporangiate, or tetrasporangiate. Endothecium developing fibrous thickenings (usually), or not developing fibrous thickenings (Lepeostegeres). Anther epidermis degenerating. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or decussate. Anther wall initially with one middle layer, or initially with more than one middle layer; of the ‘monocot’ type. Pollen grains aperturate (usually), or nonaperturate (Atkinsonia); 3(–4) aperturate; colpate; 2-celled.

Gynoecium 3 carpelled, or 4 carpelled. The pistil 1 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; inferior. Ovary 1 locular. Placentation basal. Ovules not differentiated; in the single cavity 4–12; sessile; non-arillate; not clearly differentiated from the placenta; without integuments; without obvious nucellus. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating. Synergids hooked (with filiform apparatus). Endosperm formation cellular. Embryogeny piperad.

Fruit fleshy (usually), or non-fleshy (rarely, e.g. Nuytsia); indehiscent; usually a berry, or a drupe (the fleshy part being receptacular), or a nut (Nuytsia). Seeds copiously endospermic. Endosperm oily. Seeds covered with viscous material; without a testa. Embryo well differentiated. Cotyledons 2, or 1 (often becoming fused). Embryo chlorophyllous (2/2). Polyembryony recorded.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. Not cyanogenic. Alkaloids present, or absent. Iridoids not detected. Saponins/sapogenins absent. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid present (Nuytsia). Aluminium accumulation not found.

Geography, cytology. Temperate to tropical. Pantropical and warm (especially South) temperate. X = 8–12.

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

Species 940. Genera about 70; Actinanthella, Aetanthus, Agelanthus, Alepis, Amyema, Amylotheca, Atkinsonia, Bakerella, Baratranthus, Benthamina, Berhautia, Cecarria, Cladocolea, Cyne, Dactyliophora, Decaisnina, Dendropemon, Dendropthoe, Desmaria, Diplatia, Distrianthes, Elytranthe, Emelianthe, Englerina, Erianthemum, Gaiadendron, Globimetula, Helicanthes, Helixanthera, Ileostylus, Ixocactus, Kingella, Lampas, Lepeostegeres, Lepidaria, Ligaria, Loranthus, Loxanthera, Lysiana, Macrosolen, Moquiniella, Muellerina, Notanthera, Nuytsia, Oliverella, Oncella, Oncocalyx, Oryctanthus, Oryctina, Panamanthus, Papuanthes, Pedistylis, Peraxilla, Phragmanthera, Phthirusa, Plicosepalus, Psittacanthus, Scurrula, Septulina, Socratina, Sogerianthe, Spragueanella, Struthanthus, Tapinanthus, Taxillus, Tetradyas, Thaumasianthes, Tolypanthus, Trilepidea, Tripodanthus, Tristerix, Trithecanthera, Tupeia, Vanwykia.

Illustrations. • Le Maout and Decaisne: Loranthus. • Loranthus capitatus: Thonner. • Loranthus chrysanthus, L. memecylifolius (cf Dendropthoe), and Struthanthus sp.: Lindley). • Loranthus obtusatus: R. Wight 2 (1850). • Loranthus flavidus (cf. Alepis flavida?): Hooker, Fl. Novae-Zelandiae (1853). • Peraxilla colensoi, as Loranthus: Hook Ic. Pl. 7–8, (1844). • Tupeia antarctica: Hooker, Fl. Novae-Zelandiae (1853). • Nuytsia floribunda: habitat photo (Albany, Western Australia). • Nuytsia floribunda: flowering branch (photo). • Nuytsia foribunda: habit (photo). • Peraxilla colensoi, as Loranthus: Hook. Ic. Pl. 7–8 (1844). • Leaf hairs of Loranthus ferrugineus (with foliar t.s.) and L. rufescens (Solereder, 1809).

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.’.