General description:- Herbaceous or woody plants.
Leaves:- Alternate, simple, linear, oblong or lanceolate, exstipulate, deciduous or evergreen.
Flowers:- Small, hermaphrodite or unisexual. Perianth 3- to 5-lobed or -partite, tubular to campanulate-rotate. Stamens 3-5, opposite lobes of the perianth. Ovary inferior, 1-celled. Style 1; stigma pin-headed (capitate) or lobed.
Fruit:- A small red nut or a drupe. Seed solitary, with abundant endosperm. Hemiparasites, growing on the roots of herbs or shrubs.
OSYRIS
General description:- Dioecious (with the male and female flowers on different plants); shrubs, without a rhizome.
Leaves:- Linear-lanceolate to lanceolate, evergreen. Perianth 3- or 4-partite. Male flowers in lateral few-flowered cymes; stamens 3 or 4. Female flowers solitary and terminal on short branches; stigma 3-lobed.
Fruit:- A globose drupe.
Key features:-
1) Shrubs without a rhizome.
2) Stigma 3- or 4-lobed.
3) Perianth 3- or 4-partite.
4) Dioecious.
THESIUM
General description:- Perennials, rarely annuals, without a rhizome, but often with a woody stock and sometimes producing slender stolons.
Stems:- Procumbent to erect, simple or branched.
Leaves:- Linear to lanceolate, mostly entire, 1- to 5-veined, green or yellowish-green.
Flowers:- Inflorescence a panicle with few-flowered branches, or a raceme. Flowers hermaphrodite, on short branches, with a bract and usually with 2 bracteoles. Perianth tubular to bell-shaped (campanulate)-rotate, 4- or 5-lobed, usually white inside and yellowish-green or green outside. Stamens 4 or 5. Stigma pin-headed (capitate).
Fruit:- A small green nut surmounted by the persistent, dry perianth.
Key features:-
1) Perianth-segments united.
2) Fruit a small green nut.
VISCUM
Leaves:- Opposite or whorled, with 3-7 parallel veins, coriaceous.
Flowers:- Inflorescence cymose, the flowers crowded. Perianth in 2 whorls. Calyx 4-toothed in female flowers, absent in male flowers. Petals usually 4. Stamens almost completely connate with the petals; anthers opening by pores.
Fruit:- A white, yellow or red, viscid berry.
Key features:-
1) Inflorescence cymose, sessile or very shortly pedunculate.