Phoradendron serotinum (Raf ) M C Johnst.—Mistletoe
FAMILY: Loranthaceae —the Mistletoe Family
This family is characterized by semiparasitic plants, attached to trees or shrubs by haustoria, lacking ordinary roots, but having green (chlorophyllous) leaves and stems; leaves: opposite; flowers: inconspicuous; ovary: inferior; stamens: as many as and opposite the perianth-lobes.
PHENOLOGY: Phoradendron serotinum flowers from May through July.
DISTRIBUTION: An uncommon semiparasite, mistletoe can be found parasitizing several different species of deciduous trees in Pennsylvania woods. It can be purchased from novelty shops and grocery stores at Christmas time.
PLANT CHARACTERISTICS: This species of mistletoe appears as small shrubs, parasitic on trees; leaves: coriaceous, opposite, entire, oblong to obovate, 2-6 cm, blunt or rounded; stems: freely branching, thick, brittle; calyx: deeply 3-lobed; anthers: 3, sessile on the base of the calyxlobes; ovary: ovoid, with 1 subsessile stigma; flowers: small, in short axillary spikes; fruit: a white, mucilaginous berry.
POISONOUS PARTS: The berries are especially poisonous, but leaves and stems also are toxic.
SYMPTOMS: Gastrointestinal irritation, diarrhea, weakened pulse, and cardiovascular collapse have been reported in humans. Cattle have died after consuming mistletoe but have shown no symptoms or significant lesions.
POISONOUS PRINCIPLES: The toxins are pressor amines, beta-phenylethylamine and tyramine.
CONFUSED TAXA: The familiar Christmas mistletoe has no readily confused counterparts. The nomenclature of this species has been in question; some authors cite the plant as P. flavescens (Pursh) Nutt.
SPECIES OF ANIMALS AFFECTED: Humans and cattle are susceptible to the amines in mistletoe, Other animals, including livestock and house pets, should not be allowed to eat the leaves or berries.
TREATMENT: (11a)(b); (26); (19)
OF INTEREST: For some individuals the plant can be an irritant or cause dermatitis upon contact. The alkaloid tyramine, found in mistletoe, is a vasopressor, elevating blood pressure; it is classed as an adrenergic chemical. The American Indians used P. .serotinum extracts to stop postpartum hemorrhage.