Poison ivy Rhus Rhus radicans L

Poison ivy
Rhus
Rhus radicans L.
FAMILY: Anacardiaceae

Many readers will be surprised to learn that the edible cashew nut belongs to the same family of plants as poison ivy and poison sumac. This predominantly tropical family has leaves: alternate, compound; flowers: 5-merous, polypetalous, regular, with an annular disc between the 5 stamens and ovary; ovary: 1-celled, containing I ovule; fruit: a drupe.

DISTRIBUTION:
Rhus radicans is commonly found in disturbed habitats, food plains, cultivated fields, cemeteries, waste places, along woodland paths, margins of woodlots, fencerows, roadbanks, along streams, and in urban situations around buildings and yards.

DESCRIPTION:
The species has complex and variable forms. Some are woody vines that produce aerial roots and grow by straggling and climbing over other vegetation. Ground-forms usually spread by rhizomes and develop dense colonies with a few leaves crowded near the summit. Regardless of growth habit, poison ivy always has three leaflets per leaf, with leaflets: ovate to subrotund, varying to rhombic or elliptic, terminally acute to acuminate, basally cuneate; entire to irregularly serrate or crenate; glabrous or thinly pubescent, petiolule of the terminal leaflet longer than those of the lateral leaflets; panicles: axillary, 1 dm long, bearing greenish-yellow flowers that mature into grayish white fruits, 5-6 mm; fruits: mature August through November, conspicuous all winter; birds eat the ripe seeds with impunity.

TOXIC PARTS:
All parts of poison ivy, with the possible exception of the pollen, contain toxins that cause dermatitis. It has been suggested that extremely sensitive persons might contract poison from wind-blown pollen in spring when the plant is flowering.

TOXICITY:
Dermatitis ranging from minor reddened and itching skin to major swelling, blisters, and weeping wounds can result from contact. Ingestion of leaves can cause irritation of the mucosa and digestive tract; gastritis and death may result. Animals probably are not as susceptible as humans to contact dermatitis due to hair and fur. Ingestion of leaves or other plant parts by livestock could be dangerous and result in death.

TOXIC PRINCIPLES:
The toxin 3-n-pentadecylcatechol has been isolated from Rhusradicans.

TREATMENT: For dermatitis: Antihistamines; Steroidal creams;ointments for skin inflammation; in severe cases steroid injections can reduce the reaction.