Loranthaceae

Genera Included: Actinanthella Balle, Aetanthus (Eichl.) Engl., Agelanthus Tiegh., Alepis Tiegh., Amyema Tiegh., Amylotheca Tiegh., Atkinsonia F. Muell., Bakerella Tiegh., Baratranthus (Korth.) Miq., Benthamina Tiegh., Berhautia Balle., Cecarria Barlow, Cladocolea Tiegh., Cyne Danser., Dactyliophora Tiegh., Decaisnina Tiegh., Dendropemon (Blume) Reichb., Dendrophthoe Mart., Desmaria Tiegh., Diplatia Tiegh., Distrianthes Danser, Elytranthe Blume, Emelianthe Danser, Englerina Tiegh., Erianthemum Tiegh., Gaiadendron G. Don., Globimetula Tiegh., Helicanthes Danser, Helixanthera Lour., Ileostylus Tiegh., Lampas Danser, Lepeostegeres Blume, Lepidaria Tiegh., Ligaria Tiegh., Loranthus Jacq., Loxanthera Blume, Lysiana Tiegh., Macrosolen (Blume) Reichb., Moquiniella Balle, Muellerina Tiegh., Notanthera (DC) G. Don., Nuytsia R. Brown ex G. Don f., Oedina Tiegh., Oliverella Tiegh., Oncella Tiegh., Oncocalyx Tiegh., Oryctanthus Eichl., Oryctina Tiegh., Panamanthus Kuijt, Papuanthes Danser, Passovia H. Karst., Pedistylis Wiens, Peraxilla Tiegh., Peristethium Tiegh., Phragmanthera Tiegh., Phthirusa Mart., Plicosepalus Tiegh., Psittacanthus Mart., Pusillanthus Kuijt, Scurrula L., Septulina Tiegh., Socratina S. Balle, Sogerianthe Danser, Spragueanella Balle, Struthanthus Mart., Tapinanthus (Blume) Reichb., Taxillus Tiegh., Thaumasianthes Danser, Tolypanthus Blume., Trilepidea Tiegh., Tripodanthus (Eichl.) Tiegh. Tristerix Mart., Trithecanthera Tiegh., Tupeia Cham. & Schlecht, Vanwykia Wiens.

Habit: Evergreen, shrubs and sometimes trees (Nuytsia), some vines.

Parasitism: Aerial and terrestrial hemiparasites. Nuytsia is a root parasitic tree of western Australia. Atkinsonia is a root parasitic shrub of eastern Australia.  Gaiadendron can be a terrestrial shrub or small tree in the neotropics and may even exist in the canopy, possibly parasitizing fellow epiphytes there (not directly as a mistletoe on the supporting tree).

Roots: Often forming epicortical roots which traverse the host surface and form intermittant haustorial connections. Haustoria typically large; some causing host tissue proliferation at the point of contact ("wood roses").

Stem: Dichasially branched but without nodal constrictions (as in Viscaceae); stems usually woody and brittle, glabrous to pubescent and in some cases densely lenticulate (Plicosepalus). Some squamate (e.g. Phthirusa [formerly Ixocactus] hutchisoniii).

Leaves: Simple, opposite or ternate, entire or sometimes reduced to scales; Leaf blades range from lanceolate to ovate and may be thin, leathery, or even almost succulent; they vary from pubescent to glabrous; mesophyll commonly with scattered groups of silicified cells, and often also with scattered sclereids; stomates mostly paracytic.

Inflorescence: Various types, e.g. racemes, umbels, spikes or heads but all derived from the basic dichasial unit.

Plant Sex: Flowers bisexual or rarely unisexual.

Flowers: Dichlamydous, actinomorphic or occasionally zygomorphic, epigynous; some genera with "explosive anthesis". As described by Visser (1981):

"As the bud matures the corolla lobes progressively become more turgid and strain outwards but are firmly held together at the margins. Then at the slightest touch, the corolla lobes separate explosively outwards. Simultaneously, the filaments inflex or recurve sharply thus releasing a cloud of pollen - in this way dusting the forehead of the pollinator."

Calyx: Usually represented by a toothed or shortly lobed or entire rim or shallow cup around the summit of the ovary (the calyculus). Vasculature in some (e.g. Atkinsonia) indicate the calyculus is derived from the calyx.
Corolla: Petals (3-) 5-6 (-9), valvate, free or often connate below, often forming a long corolla tube that may be equally or unequally cleft; often brightly colored (yellow, orange, red)
Nectary: Nectary disk present or not.
Androecium: As many as and opposite the petals to which they are often adnate by the filaments; anthers basifixed, tetrasporangiate and dithecal (the microsporangia sometimes cross-partitioned) or seldom with only 2 or 3 sporangia and a single theca; dehiscence by longitudinal slits. Some African Loranthaceae (e.g. Erianthemum) have coiled filaments that snap outward when the corolla is touched.
Pollen: Binucleate, with 3 or seldom 4 apertures (inaperturate in Atkinsonia); usually trilobate or triangular, seldom spherical.
Gynoecium: Compound ovary of 3-4 carpels, inferior, unilocular (or solid with no locule) or rarely (Lysiana) with 4 locules and an axile placenta. Ovules several, commonly 4-12 embedded in the erect, free-central placental column or ovules embedded in the basal tissue of the ovary (mamelon).
Ovule: Without nucellus and integuments.
Embryo, etc.: Monosporic with an 8-nucleate embryo sac; embryo sac development complex and unusual; embryo sac often intrusive, growing through a portion or the entire length of the style; embryo with a highly elongated suspensor.

Fruit: Usually a lactiferous berry or drupe with one seed, but in Nuytsia a winged samara-like fruit; the calyculus is often persistent on the top of the fruit (accrescent); viscid layer forms outside the vascular bundles enveloping the seed.

Seed: Lacks a testa; surrounded or capped at one end with vicid tissue; often containing more than one embryo; embryo large, axile; cotyledons initially 2 but often becoming fused during ontogeny; endosperm copious, starchy, compound and derived from several primary endosperm nuclei; endosperm usually without chlorophyll (except Lysiana -- considered to have evolved independently -- Kuijt, 1968).

Chromosomes: 8-12 [12-18 in Barlow and Wiens 1971]

Link to Family Description in Delta