Santalaceae R. Br. (1810), emend. Der & Nickrent

Habit: Root parasitic trees, shrubs and stem parasitic shrubs (mistletoes).

Parasitism: root and stem hemiparasites.  Confirmed root parasitism in Colpoon (Visser 1981), Exocarpos (Rao 1942; Philipson 1959; Fineran 1963, 1965), Nestronia (Melvin 1956), Osyris (Planchon 1858, Ferrarini 1950), Santalum (Barber 1907, 1908). Parasitism in the three aerial parasites (Antidaphne, Eubrachion, and Lepidoceras) is obvious.

Roots: Haustorial. 

Stem:  Branches glabrous or pubescent. 

Leaves: alternate and opposite, persistent, caducous or deciduous, dimorphic or not, developed or as scales (squamate). Leaf cystoliths absent. 

Inflorescence: axillary and terminal and of various types: solitary flowers, monochasia, spikes, cymes (simple and compound dichasia), panicles, fascicles, and umbels.  Floral and inflorescence trichomes absent or present.  Floral bracts and/or bracteoles free (not fused), persistent, caducous or deciduous. 

Plant Sex: various with bisexual flowers, dioecious, monoecious, andromonoecious, and androdioecious conditions seen. Flowers in the three aerial parasites (Antidaphne, Eubrachion, and Lepidoceras) are unisexual, lacking staminodes and pistillodes (Kuijt 1988).

Flowers:  Pedicel (or stipe) present or absent (then the flowers sessile). 

• Calyx: generally absent; calyculus present in Myoschilos.
• Corolla: Petals 3-6, free or fused into a corolla tube that is short or campanulate or urceolate. Corolla hairs behind anthers present or absent (Exocarpos, Omphacomeria and mistletoes). 
• Nectary: Glandular disk and lobes present, absent, or not well-defined.
• Androecium: 3-5 stamens, as many as the perianth lobes and opposite them.  Filament very short, shorter than, equal to or longer than anther.  Anthers dorsifixed or basifixed, 4-locular (tetrasporangiate), positioned in one plane. Locules of equal size (isomerous), arranged parallel (longitudinal) to filament, thecal dehiscence by longitudinal by slits, each loculus opening individually or both thecal locules using a common opening. 
• Staminodia: Staminodes and pistillodes sometimes present (e.g. Omphacomeria). 
• Pollen: Kuijt (1988) shows SEM photos of the three eremolepidaceous mistletoes (Antidaphne, Eubrachion, and Lepidoceras).
• Gynoecium: The ovary position varies from half-inferior (e.g. Exocarpos, Santalum) to inferior (e.g. Colpoon).   Ovary unilocular throughout or multilocular below and unilocular above. In some genera, such as Colpoon, Rhoiacarpos and Osyris the locule is lobed at the base thus suggesting carpel number. Style shape variable: short cylindrical or conical or medium to long cylindrical.  Stigma 2- to 5-lobed and globular or capitate.  Placental column straight (not twisted), sometimes extended apically beyond ovules to base of style.
• Ovule: 1-5, ategmic.
• Embryo, etc.: female gametophyte from placenta or mammelon, and embryo sac sometimes extending beyond ovule or placenta.  Suspensor present. Embryology of Santalum and Osyris reported in Paliwal (1956) and Rao (1942), Eubrachion (Bhandari and Indira 1969), and Exocarpos (Bhatnagar 1991).

Seed: one per fruit.

Chromosomes: Chromosome numbers have been reported for Antidaphne viscoidea: n = 13 (Wiens & Barlow, 1971), Antidaphne andina [as Eremolepis glaziovii]: n = 10 (Wiens & Barlow, 1971), Lepidoceras chilense: n = ca. 11 (Barlow & Wiens, 1971), Exocarpos gaudichaudii: n = 10 (Carr, 1978), Osyris arborea: n = 20 (Bedi & al., 1981), O. quadripartita: n = 20 (Valdes-Bermejo, 1980), O. wightiana: n = 15 (Mehra, 1976), Santalum acuminatum: n = 10 (Harbaugh, 2008), S. album: n = 20, 20+B (Selvaraj & Subramanian, 1982), S. ellipticum: n = 20 (Carr, 1978), S. freycinetianum: n = 20 (Carr, 1978), S. paniculatum: n = 20 (Carr, 1978), and S. spicatum n = 10 (Harbaugh, 2008). For a discussion of polyploidy in Santalum, see Harbaugh (2008).

Alternate Family Names: Exocarpaceae Gagnep., Osyrinae (Osyridaceae) Link.

Link to Description in Delta (Santalaceae - in the broad sense)

Link to Description in Delta (Eremolepidaceae)