The only member of this large and diverse family with known poisonous properties is Hydrangea. The characteristics of Hydrangea, provided below, replace the family description.
PHENOLOGY: The introduced common garden hydrangea, H. macrophylla, flowers in midsummer. The native tree hydrangea or hills-of-snow (H. arborescens) is found blooming June and July, while the introduced PeeGee hydrangea (H. paniculata) flowers later in the season, during August and September.
DISTRIBUTION: The garden hydrangea is a well known, "old fashioned" ornamental cultivated for display in outdoor plantings, pots, or tubs. The hills-of-snow is a garden cultivar of the native H. arborescens that is found on dry or moist rocky woods and hillsides. The PeeGee hydrangea, H. paniculata, is a native of eastern Asia, also used in landscaping.
PLANT CHARACTERISTICS: The hydrangeas mentioned above have leaves: deciduous, opposite, petioled, toothed; flowers: in flat-topped or globular terminal cymes, often with the outer flowers sterile and much enlarged relative to the inner ones, ranging in color from white to pink, lavender, or blue; flowers: 5-merous; sepals: showy; ovary: inferior, or nearly so; fruits: dry capsules containing many small seeds.
POISONOUS PARTS: The leaves and buds contain the poisonous constituents.
SYMPTOMS: Under certain conditions the toxins produce gastrointestinal upset, nausea, diarrhea (bloody), and vomiting.
POISONOUS PRINCIPLES: Research indicates that hydrangea sometimes contains a cyanogenic glycoside, hydrangin. Other constituents include saponin, resins, fixed and volatile oils, and starch.
CONFUSED TAXA: The hydrangeas are popular cultivated plants not easily confused with other taxa.
SPECIES OF ANIMALS AFFECTED: Both livestock and human cases have been reported. Sickness was painful but recovery occurred.
TREATMENT: (11a)(b); treat for cyanide poisoning.
OF INTEREST: Analysis of poisoned victims does not always show symptoms compatible with cyanide poisoning. Roots of H. arborescens were used by American pioneers in the treatment of dyspepsia.