Poisonous Plants in New Zealand - external poisons (skin irritants)
Individual reactions to external poisons vary enormously. Some people are immune while others are so susceptible that even gentle handling can produce an adverse reaction.
Agapanthus (Agapanthus species). The slimy sap can affect some people's skins, although generally only adults seem to be susceptible.
Amaryllids (Amaryllis species, especially A. belladonna, and including Hippeastrum species). They have the same sap features as agapanthus.
Garden primulas (Primula species, especially P. malacoides and P. obconica). Some people are susceptible to these plants and contact can cause intense skin irritation. The common garden weed, scarlet pimpernel (Anagallis arvensis), belongs to the primula family and has occasionally caused dermatitis when handled.
Giant hogweed (Heracleum mantegazzianum). A powerful skin irritant that affects susceptible people more noticeably in sunny weather. Found mainly in eastern South Island.
Ivy (Hedera helix). Sometimes causes skin irritation when handled.
Japanese wax-tree [see wax-tree]
Nettles or stinging nettles (Urtica species). Three species are likely to be encountered - the first two are introduced and the third is native. Nettle or annual nettle (U. urens) is a common weed of gardens and waste places, especially where animals congregate. Perennial nettle (U. dioica) is much less common, but may grow in partly shaded places in the vicinity of buildings. The notorious giant native tree nettle or ongaonga (U. ferox) does not occur naturally in Auckland, although it is present north of the Waikato, as well as many areas to the south including the South Island. The stings can cause a numbing effect which lasts several days.
Parsnip (Pastinaca sativa). May cause rashes in susceptible people when leaves are rubbed against the skin.
Rue (Ruta graveolus). This small, very unpleasantly scented shrub is grown by people interested in herbs. It can cause skin irritation and even blistering when handled.
Smoke bushes (Cotinus species). Contact with sap in stems, shoots, and leaves can cause inflamma-tion and irritation for susceptible people. Closely related to Toxicodendron species, but not nearly as poisonous as them.
Spurges (Euphorbia species). The white sap can irritate skin; especially beware of caper spurge (E. lathyris). This plant has nothing to do with true edible capers.
Stinging nettles [see nettles]
Sumacs [see wax-tree]
Varnish tree [see wax-tree]
Wax-tree, Japanese wax tree or varnish tree (Toxicodendron succedanea). Susceptible people suffer blistering and skin inflammation with great irritation, that can result in temporary hospitalisation, although other people are immune. Some other members of the family to which this plant belongs are notorious for causing severe skin irritation like the wax tree. Fortunately they rarely grow in New Zealand, eg. poison ivy (T. radicans), from North America and Chinese lacquer tree (T. vernicifluum) that like the wax tree is from China and long cultivated in Japan. Note: the species of Toxicodendron have often been included in the large genus Rhus, but the Rhus species rarely cause trouble, eg. in many parts of New Zealand staghorn sumac (Rhus typhina) is commonly grown. The family has many tropical members, some of which can cause severe skin disorders, but ripe fruits and seeds of mangoes and cashew nuts are quite safe to handle although the trees upon which they grow are not.
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