Unsafe, Toxic & Poisonous Plants
A quick word about the lists/plant info on this website...
All of the information on the lists here has either been researched independently or has come from verifiable, trustworthy sources, and then double checked by me. MANY so called rabbit safe plant lists are not only inaccurate, but are unsafe and have simply been copied from other so called ‘safe’ lists.
One needs to remember that these lists - which are found on websites and/or various FaceBook groups are only as good as the person who compiled them and most have not been researched independently after being copied from yet another so called safe list....
It's a bit like Chinese whispers and the end result is not necessarily safe, accurate or pertinent to pet rabbits living in New Zealand. Whilst the lists of plants here are my opinion, they are researched and verified by me as being safe - or otherwise, and are not simply copied/parroted from other sources.
Something else to consider is that plants included on overseas lists are often growing in very different conditions to those here in New Zealand. Many that are not considered problematic overseas are known to cause issues with stock when fed in NZ. One of the reasons for this is that our climate is very different to that of the ‘home country’ of these plants. In their countries of origin, hard winters often mean the plants are dormant for a good portion of the year. Whereas in NZ, they may grow year round. This is of course why plants such as Gorse and Blackberry are serious pest plants in NZ but are well mannered, useful plants on their home turf. This unchecked growth can also potentially mean that their less desirable constituents may be concentrated to unsafe levels.
Plant ID Apps - the use of these to accurately ID plants for consumption is not advisable. These Apps are not trustworthy (I've tested 3 so far with scary results) and can often give an answer that is not only inaccurate, but can be simply dangerous. I do not claim to 'know it all' and if I don't know the ID/safety of a plant, I will say so and will then do my level best to both ID the plant and ascertain it's safety etc. because the well being and safety of your rabbits is my top priority.
No list can be 100% complete or exhaustive, however this list contains the plants that you are most likely to come across in NZ.
It is as comprehensive as possible and is continually being reviewed and updated.
Please don’t assume that because a plant is not listed here, that it is safe to feed.
Prunus Species - Cherry, Plum, Apricot, Peach Trees, Flowering Cherries ***DO NOT FEED***
These trees contain Amygdalin which is classified as a cyanogenic glycoside. When fresh plant material is macerated as in chewing, this allows enzymes and cyanogenic glycosides to come together, releasing hydrogen cyanide. It is found in the wood, leaves, roots, fruit and seeds. The highest concentration is in the kernels. This compound is also found in Apple and Pear seeds which is why it is advised to avoid feeding them.
Amygdalin content in four stone fruit species at different developmental stages
Coniferous Trees
Numerous coniferous trees appear on various 'safe' lists all over the internet. But before you decided to go and pick the tree you have growing in your garden and feed it to your rabbits there are a number of important things to consider...
First - This family of plants can be very difficult to identify accurately for the 'layman' ... so, are you 100% certain of your ID?
Secondly - How safe is the 'safe' list? Has it been independently researched or simply copied from other so called 'safe' lists? Just because someone found it on a safe list and copied it, does not make it safe...
Lastly and most importantly - Many coniferous tress and shrubs are highly poisonous with the potential to kill.
The most poisonous members of the family include the Cupressaceae/Cypress (which includes C. macrocarpa, commonly found in NZ), Pinaceae/Pines and Taxaceae/Yew. Other conifers including the Pinaceae sub families - Picea/Spruces & Abies/Firs and the Cupressaceae sub family Sequoia/Redwoods are referred to a potentially toxic.
All Conifers contain a variety of tannins, resins, oils and acrid irritant substances to which their toxic properties are attributed however often little is known about their mode of action and precise action, so it’s just best to avoid the whole lot for safety’s sake.
Pine Cones are included in this caution. They can also potentially cause blockages if ingested so are best just left for the fire place!
Citrus Trees
Whilst citrus trees aren’t classed as ‘toxic’ per se, they are high in aromatic oils which have the potential to upset the gut so it won’t hurt if they have a small nibble in passing, but I don’t recommend picking them to feed or allowing unrestricted access.
Ferns and Lilies
These are toxic to rabbits.
Day Lilies / Hemerocllis
These are no longer classified in the same plant family as Lilies. Opinions vary but I don’t feed just to be safe, however a nibble probably won’t hurt.
Should You Eat Daylilies? Safety, Toxicity, and Other Facts
The Myrtle Family
Included in this family are the following trees/shrubs that we are often asked about -
* Feijoa
* Pohutukawa
* Bottlebrush
* Guava
* Monkey Apple
* Manuka & Kanuka
* Willow Myrtle
The Myrtaceae family is well known for its toxicity. Indeed, a main feature of this family is their highly aromatic foliage and timber, a great many are used for essential oil extraction and many are toxic. That's enough for them to be a pretty firm no for me. I would strongly advise against feeding either the leaves or the wood.
The Myrtaceae Family Wiki
This study discusses Essential Oils from the Myrtaceae family -
Essential oils isolated from Myrtaceae family as natural insecticides
Below is information about plants commonly grown in New Zealand, which are noted to have properties which range from undesirable to highly toxic. Whilst not specific to rabbits, it can serve as a useful guide = Just AVOID them !!!!
Plants in New Zealand Poisonous to Children - so let’s include rabbits in that!
Safety in pre-school Centres - and rabbit gardens!
New Zealand natives are marked with an *
Agapanthus This plant is poisonous.
American Fireweed (Erechtites hieraciifolius)
Angel's trumpet (Brugmansia candida) All parts extremely toxic.
Anthurium (Flamingo flower) Very high in Calcium Oxalates.
Apple of Peru (Nicandra physaloides) - Leaves and unripe fruit are the most toxic part.
Apple of Sodum (Solanaum sodomeum) - the green fruits are the most toxic part.
Apricot (Prunus armeniaca) See note above
Arum (Zantedeschia species)All parts are poisonous.
Ash (Fraxinus species) - High in tannins. Can cause Ash poisoning in ruminants resulting in death. Can also cause contact dermatitis.
Asparagus fern (Asparagus densiflorus) + Asparagus (Asparagus officinalis).
Avocado The whole plant contains a fungicidal toxin called Persin.
Azalea - Related to Rhododendrum. All parts are toxic, but the leaves and the nectar contain a toxin that is more detrimental. These can obstruct the rhythm of the heart causing an arrhythmia or cardiac arrest.
Bamboo The stems can splinter, damaging the mouth and can pierce the gut wall. The fibres can also lodge in the teeth. LEAVES ONLY are ok.
Bay Tree (Laurel nobilis)
Beech (Fagus sp) Beech nuts contain a compound called fagin which is loosely classified as a toxic alkaloid at present. In regard to feeding fresh tree prunings the issue is that Beech is part of the Fagaceae family, same as oak. Fresh foliage of both has high tannins but Beech is also high in oxalic acid. Dried/dead Beech wood is less likely to be an issue.
Begonia - Considered to be toxic due to its very high levels of Oxalates and Cucurbitacin B. The tuber and roots are the most toxic.
Bitter Almond (Prunus dulcis var. amara) Bitter almond kernels are poisonous due to cyanogenic glycosides and amygdalin.
Bittersweet (Solanum dulcamara) Whole plant is highly toxic.
Black Nightshade (Solanum nigrum and similar species) Poisonous - esp the green/unripe berries.
Blue Pimpernel (Lysimachia monelli) If consumed, it can be toxic to livestock and humans. Toxicity level ranges from virtually nontoxic to fatally toxic and appears to correlate with summer rainfall levels.
Borage (Borago officinalis) Similar properties to Comfrey; high in pyrrolizidine alkaloids which seriously damage the liver and are carcinogenic. Flowers can be given as a treat.
Bottlebrush (Callistemon) - Myrtle Family, see note above
Box (Buxus semoervirens) Whole plant is poisonous.
Boxthorn (Lycium ferocissimum) Berries, leaves, stems and roots contain alkaloids that are toxic to humans and livestock
Broom (Cytisus scoparius) All parts are toxic.
Burdock (Arctium lappa) Not a palatable plant. The leaves can cause contact dermatitis. Seed hairs are toxic. The root only, is used medicinally.
Bush Germander (Teucrium fruticans) Dose dependent toxicity causing liver failure and death
Bushman's Poison (Acokanthera oppositifolia & relative species) All parts of this tree are highly toxic.
Buttercups (Ranunculis several species) All parts poisonous but toxins are degraded by drying, so hay containing dried buttercups is safe.
* Cabbage Tree (Cordyline australis) - whilst I’ve not been able to establish if there are any toxicity issues - although it shares the same family tree as Yucca... this plant is extremely tough & fibrous so there is a risk of fibres lodging in the teeth so I put it in the ‘don’t pick to feed, but ok if nibbled’ category.
Calico bush (Kalmia latifolia) All parts highly toxic.
Camellia - foliage is high in oxalates so do not feed. The odd flower will be ok.
Cape Honey Flower (Melianthus major) Entire plants is highly toxic.
Cape Tulip (Homeria collina) All parts highly poisonous.
Cape Weed (Arctotheca calendula)
Caper spurge (Euphorbia lathyris) All part are toxic.
Castor Oil Plant (Ricinus communis) The seeds are the most poisonous.
Cestrum (Cestrum species) Unripe seeds are poisonous.
Cherry Laurel (Prunus several species) Leaves and seed may cause severe if ingested. The seeds contained within the cherries are poisonous like the rest of the plant, containing cyanogenic glycosides and amygdalin. This chemical composition is what gives the smell of almonds when the leaves are crushed. Laurel water - a distillation made from the plant contains prussic acid (hydrogen cyanide) and other compounds and is toxic.
Chilean Jasmine (Mandevilla laxa) White sap is toxic
Chinaberry (Melia azedarach) Yellow fruits are toxic.
Chrysanthemum - All parts toxic to animals.
Citrus Trees Whilst citrus trees aren’t classed as ‘toxic’ per se, they are high in aromatic oils which have the potential to upset the gut so it won’t hurt if they have a small nibble in passing, but don’t pick to feed them or allow unrestricted access.
Climbing Spindle Berry (Celastrus orbiculatus) - All parts toxic.
Comfrey (Symphytum officinale and its hybrids) - Contains cumulative hepatic toxins.
Coniferous Trees See note above
Convolvulus / Morning Glory / Bindweed Opinions vary. But my stance is this - some forms are potently Hallucinogenic + have other nasty components and because most people would struggle to differentiate between the various types, it is simply best to avoid it completely. There are so many other good things to feed instead!
Coprosma species - this contains a substance which is mildly laxative & purgative and although the seedlings are recorded as being eaten by wild rabbits I’d not feed deliberately.
Corn Marigold (Glebionis segetum)
Corncockle (Agrostemma githago) - all parts of this plant are poisonous.
Cosmos contain a Glycoside called Cosmosiin which has been shown to exhibit anti-platelet function which could affect the bloods ability to clot.
Corokia Contains some potent phytochemicals. Not toxic as such as far as I can tell from my reading, and a nibble probably won’t hurt but I’d not pick to feed.
Cotoneaster Cotoneasters' leaves, berries and flowers all contain cyanogenic glycosides.
Creeping Mallow (Modiola caroliniana)
Cucurbitans - Cucumber, Courgette, Choko, Pumpkin - all leaves contain cucurbitacins which can cause gut disturbance and can be toxic in large amounts. Even small amounts can cause stomach cramps. Choko fruit skin releases a sticky latex-based sap that can cause numbness or irritation of skin and mucous membranes. Cucurbitan fruits in general have low fibre:water ratio which increases the risk of poopy butt.
Daisy (Bellis perennis) Don’t pick to feed. Flowers ok of eaten whilst out grazing.
Daffodil (Narcissus several species) Bulbs are poisonous.
Daphne (Daphne several species) Fruits and Leaves toxic.
Deadly Nightshade (Atropa belladonna) - Highly toxic. Rare in NZ.
Daisy Osteospermum (Dimorphotheca species) All parts toxic.
Dock (Rumex sp) Incl all Docks. High in Oxalates.
Dumb Canes (Dieffenbachia species). They are popular as house plants. All parts toxic.
Elephant Ear (Alocasia macrorrhiza) All parts toxic.
Elm (Ulmus)
Esler’s Weed (Senecio esleri)
European Beech (Fagus sylvatica) Raw seeds are the most toxic part.
Evening Primrose (Oenothera biennis)
False Acacia (Robinia pseudoacacia) The leaves, young shoots, pods, seeds and the bark contain toxic components.
Fathen (Chenopodium album)
Feijoa - (Acca sellowiana) Myrtle family, see note above. A great many plants in this family are used to make Essential Oils and Feijoa is also highly aromatic which is another sign that it should be avoided for rabbits. I would strongly advise against feeding either the leaves or the wood.
* Five Finger or Whauwhaupaku (Pseudopanax arboreus) Since it belongs to the ivy family, some parts of the plant are poisonous if ingested.
Fig (Ficus carica) Sap is toxic.
Fir (Abies sp) See note about Coniferous trees, above.
Firethorn (Genus:Pyracantha) Berries mildy poisonous.
* Flax/Harekeke (Phormium tenax) Green and Red Flax contain extremely tough fibres which can lodge in front teeth. The blades of the plant also contain cucurbitacins one of which is toxic and poisonous to some animals. Cucurbitacins in general also have the potential to cause GI pain and upset so are best avoided when feeding rabbits. I’d definitely not feed it to rabbits deliberately. ‘Flaxseed’ as sold in the shops does NOT refer to the seeds of NZ flax plants, but to the seeds of Linum usitatissimum L.
Fleabane (Erigeron bonariensis)
Flowering Cherry (Prunus sp) - all ornamental Cherries. Treat the same as other drupe bearing trees. Blossom is ok as a treat. See note above re Prunus species. Flowers are ok as an occasional treat.
Forgetmenot (Myosotis sp.)
Foxglove (Digitalis purpurea) All parts highly toxic.
Fumitory (Fumaria officinalis) - member of the poppy family. Contains numerous alkaloids that can have toxic side effects.
Galinsoga (Galinsoga parviflora)
Gardenia (Gardenia jaminoides) Contain toxic substances such as genioposide and gardenoside, which cause symptoms such as mild vomiting, diarrhoea and hives.
Giant Hogweed (Heracleum mantegazzianum) Sap highly toxic.
Ginkgo biloba the flesh of the fruit causes blistering dermatitis and the nuts contain cyanogenic glycosides (which are toxic) are also a choking/gut blockage hazard. Foliage is used medicinally/has bio active properties the safety of which is not established for rabbits. Often listed as rabbit resistant which indicates it is probably considered unpalatable by rabbits, a nibble probably won’t hurt but I woulnd’t pick to feed.
Gleditsia is generally regarded as a non toxic tree, but because it is from the Fabaceae/Pea family, it could potentially be gassy. One study also found the leaves were a cardiac depressant. Therefore, I'd not feed it.
Gloriosa Lily (Gloriosa superba) All parts poisonous.
Goat's rue (Galega officinalis) - Best avoided. Leaves and flowering tops contain numerous guanidine derivatives, including galegine which may cause hypoglycemia. Known to be toxic to livestock.
Goji (Lycium sp) - Night shade family so don’t feed the branches, leaves etc.
Golden chain tree (Laburnum anagyroides) All parts highly toxic.
Groundsel (Senecio vulgaris)
Guava (Psidium cattleyanum) Cherry/Strawberry Guava. Myrtle family, see note above.
Hebe/Veronica Not one to pick and feed but most probably won’t harm if nibbled.
Hedge Woundwort (Stachys sylvatica)
Hedge Mustard (Sisymbrium officinale)
Hellbore (Helliborus species) All parts highly toxic.
Hemlock (Conium maculatum) All parts highly toxic.
Henbane (Hyoscyamus niger) All parts highly poisonous.
Holly (Ilex several species) Leaves and fruit highly toxic.
Honeysuckle Vine Contain glycosides in the stems or vines, and carotenoids in the berries. These are generally only mildly toxic in humans, but can be harmful to animals and small children. Flowers ok as a treat, vine ok if nibbled but I’d not pick to feed. Berries are toxic
Horse Chestnut (Aesculus hippocastanum) The highly toxic parts are the raw seeds, leaf, bark, flowers.
Hydrangea (Hydrangea species) All parts of the plant (bark, leaves and the flower buds) moderately toxic.
Hydrocotyle species. The family has a lot of ‘no’ members in it incl Hemlock. My rabbits tend to ignore lawn Hydrocotyle.
Hyssop Loosestrife (Lythrum hyssopifolia)
Inkweed (Phytolacca octandra) The poisonous parts are the berries, leaves and roots.
Iceland Poppy (Papaver nudicaule and its cultivars) All parts poisonous.
Impatiens (Impatiens walleriana) High in oxaltes. Known to cause vomiting and diarrhoea.
Ink Weed (Phytolacca octandra)
Iris (Iris several species) The poisonous parts are the rhizomes, bulbs and stem.
Italian Arum (Arum italicum) All parts are extremely poisonous including the sap
Ivy (Hedera helix) All parts are poisonous including the berries.
Ivy Leaved Toadflax (Cymbalaria muralis)
Japanese Knotweed (Reynoutria japonica)
Jasmine / Star Jasmine Trachelospermum jasminoides The entire plant is considered mildly poisonous.
Jasmine (Jasminum officinale) sap is a skin irritant. Ok if nibbled. Don’t pick to feed.
Juniper (Juniperous sp) See notes about Coniferous trees, above.
Jerusalem Cherries (Solanum pseudocapsicum & Solanum diflorum) The highly toxic parts if ingested are the berries and the leaves.
* Karaka (Cornyocarpus laevigatus) Karaka berries contain highly poisonous kernels.
Khasia berry (Cotoneaster simonsii) The berries are mildly poisonous.
Kiwifruit Vines - leaves and wood. The leaves of Kiwifruit are very high in Oxalates so are best avoided. I would include the timber as well, just to be on the safe side.
* Kowhai (Sophora several species) All parts of the plant but especially the ripe yellow seed are poisonous.
Laburnum (Laburnum anagyroides) All parts of this plant are highly toxic if ingested.
Lantana (Lantana camara) The highly toxic parts of this plant are the unripe, green berries and the leaves.
Larkspur (Delphinium several species) All highly toxic parts of this plant are poisonous.
Lily of the Valley (Convallaria majalis) All parts are poisonous if large quantities are ingested.
Lily of the Valley shrub (Pieris species) All parts of the Pieris species are highly poisonous especially the leaves and nectar from flowers.
Lupins (Lupinus species) Their toxicity depends upon season, species, and part of the plant. Toxins are particularly found in the pods, seeds and young leaves.
Macrocarpa - toxicity seems to be mainly an issue with foliage ingestion but I would not risk the timber being chewed or eaten either. See note on Coniferous trees, above.
* Manuka (Leptospermum scoparium) - Myrtle family, see note above.
Maples - Certain Maples are highly toxic and whilst others may be ok. There are documented cases of toxicity especially from dried or fallen leaves and although there are lesser levels of toxins in fresh leaves it is not one to feed. Both leaves and bark should be avoided. Maple has links with blood disorders, with documented cases of haemolytic anaemia in horses. Just because a plant appears on ‘safe feed lists’ does not mean it is safe.
Red Maple Leaf Poisoning in Horses
Horse-killing toxins identified in maple leaves
Marigold (Tagetes) - cause digestive tract irritation and irritation to skin particularly in sunlight. Not to be confused with Calendula.
Marsh Marigold (Caltha palustris) All parts of this plant are poisonous and can be an irritant.
Milkweed (Euphorbia several species) All parts of the plant are poisonous.
Monkey Musk (Erythranthe moschata)
Monkshood Aconite (Aconitum napeilus) All parts highly toxic.
Morning Glory (Ipomoea species) All or parts of this plant are poisonous.
Moth Vine or Cruel Vine (Araujia sericifera) Has white latex in all parts of the plant that is poisonous.
Mountain laurel (Kalmia latifolia) All parts of Kalmia latifolia are toxic, especially the young shoots and leaves.
* Mountain Tutu (Coriaria plumose) All parts of the plant are highly toxic.
Mugwort (Artemisia sp.)
Natal lily (Clivia miniata) Poisonous.
* New Zealand Blueberry (Dianella nigra) also called Dianella intermedia. Berries are poisonous.
* Ngaio (Myoporum laetum & Myoporum insulare) Whole plant highly poisonous.
Oak Green acorns and new spring growth is poisonous.
Overview of Quercus Poisoning
Oak Poisoning in Cattle
Oleander (Nerium oleander) The whole plant is highly toxic.
Oxalis (Oxalis sp.) Very high in Oxalates.
Oxeye Daisy (Leucanthemum vulgare) - no nutritional benefit. Extremely bitter and unpalatable. Avoided by wild rabbits in general, so best avoided.
Palmgrass - Setaria palmifolia - Although it is actually a grass (the flower heads give that away) and as such is used as fodder in some countries, the leaves and roots both have rough hairs and spikes which can cause serious irritation and it is also known to cause Oxalate poisoning. So for me this would be a "ok if nibbled in passing but definitely do not pick to feed."
Parsley Dropwort (Oenanthe javanica)
Parsnip The tops can cause serious skin irritation, the roots, whilst 'safe' are very high in sugar so are best avoided and the peelings can contain a substance that is potentially toxic. So for me Parsnip is just a no across the board.
Passionfruit fruit, flowers and leaves contain cyanogenic glycoside which breaks down to cyanide, so best not to allow access.
Cyanogenesis of Passiflora edulis
Peach (Prunus persica) See note above.
Peony This plant contains the toxin, paeonol, which is concentrated in the bark. When ingested in large amounts, it can cause gastrointestinal distress (e.g., vomiting, diarrhea, etc.). I would avoid all parts of the plant to be on the safe side.
Perilla I put Perilla in the definite NO box. It is well know to be toxic to livestock causing respiratory distress, lung inflammation, ultimately pneumonia and death. There is no treatment for Perilla poisoning.
Petunias Flowers probably ok. Foliage not safe to eat.
Photonia - Red Robin - Listed as being toxic to horses and ruminants.
* Pittosporum species - Pittosporum sp. are high in a great many volatile compounds including terpenes and are also high in saponins. All of these have the potential to upset the gut. They are not a plant I would ever pick to feed and whilst the odd nibble in passing probably won't hurt I would avoid ingestion if possible.
* Pohutukawa From the Myrtle family, see note above. Best avoided.
Poinsettia Euphorbia family so best avoided.
Poison Ivy (Toxicodendron radicans) Synonyms: Rhus radicans, Rhus toxicodendron. Sap is an extreme irritant.
Polyanthus & Primula The poisonous part of primula is allergens that appear to be concentrated in the glandular hairs on leaves and stems. These allergens cause dermatitis. The main allergens are primin, primetin, miconidin and possibly quinones. Symptoms can be an allergic skin irritation (redness, blisters, swelling), mainly on hands and face, following contact. Dogs are susceptible to these primula allergens.
Poppy (Papaver several species) The highly toxic part of a poppy is the milky sap from all parts, but mainly the fruits.
* Poroporo (Solanum laciniatum) The highly toxic parts of this plant are the leaves and berries.
Potato (Solanum tuberosum) Leaves, roots and stems poisonous, + green skin snd eyes of the tuber.
Privet (Ligustrum several species) The highly toxic parts of this plant are the leaves and the berries and should be handled with care.
Pumpkin/Cucumber/Courgette Leaves Leaves contain Cucurbitacins which can be toxic in large amounts - even small amounts can cause stomach cramps. The leaves aren't very palatable to most rabbits though.
Purple Toadflax (Linaria purpurea) Toxic to stock and slightly toxic to humans.
Ragwort (Jacobaea vulgaris) Highly poisonous esp when wilted.
* Rangiora (Brachyglottis repanda) All parts of this tree are highly poisonous.
Red horse-chestnut (Aesculus x carnea) Nuts are poisonous.
Rhododendron (Rhododendron species) All parts of this plant are extremely toxic to humans and animals.
Rhubarb (Rheum rhaponticum) The toxic part of rhubarb is the raw leaves.
Robinia The whole tree is toxic.
Rowan/Mountain Ash (Sorbus aucuparia) Contains cyanogenic glycosides (same as stone fruit trees). Irritation of the mucous membranes and a CNS irritant.
Scarlet Pimpernel (Anagallis arvensis) If consumed, it can be toxic to livestock and humans. Toxicity level ranges from virtually nontoxic to fatally toxic and appears to correlate with summer rainfall levels.
Scentless Mayweed (Tripleurospermum inodorum) Contains polyacetylene compounds whose pharmacological properties are similar to those of Alkaloides and many are known to be toxic to animals. There is no record of this plant being used in folk/traditional medicine either which indicates its undesirable qualities, so just best avoided.
Selfheal (Prunella vulgaris)
Silk Tree / Mimosa tree (Albizia julibrissin) - seed pods are toxic. Toxicity of Mimosa Tree
Soapwort (Saponaria officinalis)
Soldier’s Buttons (Cotula australis)
Spanish Broom (Spartium junceum) The whole plant is toxic, especially the seeds.
Speedwells (Veronica persica, Veronica filiformis)
Spindle Tree and Japanese spindle tree (Euonymus europaeus and E. japonicus) All parts of this tree are highly toxic.
Spruce (Picea sp) See note re Coniferous trees, above.
Spurge (Euphoria sp.) Sap is toxic.
Spurrey (Spergula arvensis)
Staggerweed (Stachys arvensis)- known to cause staggers in livestock.
Stinking Mayweed (Anthemis cotula)
Stinkwort (Dittrichia graveolens)
Stork’s Bill (Erodium cicutarium) - known to cause staggers in livestock.
Sycamore - Acer pseudoplatanus A large deciduous tree of the Maple family. Seed toxicity recorded for horses, best avoided.
Hypoglycin A Concentrations in Maple Tree Species in the Netherlands and the Occurrence of Atypical Myopathy in Horses
Swanplant is toxic. Swallowing even a small amount could be a problem. Ingestion of the plant material can affect the heart, breathing, central nervous system and the stomach.
Tarweed (Deinandra fasciculata)
Taro (Colocasia esculenta) Whole plant is poisonous when raw.
Thorn Apple (Datura stramonium) All parts, mainly seeds and leaves are toxic.
* Titoki (Alectryon excelsus) Many plants in the Alectryon family are poisonous. The round black seeds are best avoided despite limited information on their toxicity.
* Totara - Has toxic components.
* Tree Nettle (Urtica ferox) The tree nettle is one of New Zealand's most poisonous native plants.
Tree of Heaven (Ailanthus altissima) It is reported that all parts of this tree is poisonous.
Tutsan (Hypericum androsaemum) - a member of the St. John's-Wort family, berries poisonous.
* Tutu (Coriaria species) All parts of the plant are poisonous.
Wallflower (Erysimum cheiri) contains the chemical compound cheiranthin which has a stronger cardiotonic action than digitalis (obtained from Digitalis species like Foxglove) and whilst it is sometimes used medicinally (with extreme caution) as a Cardiotonic, if taken in large doses it is very poisonous.
Water Celery (Oenanthe javanica)
Water Spinach (Ipomoea aquatica)
Wattle (Acacia sp) - ALL Acacia should be regarded as toxic. Many contain psychoactive alkaloids, are high in tannins and some contain potassium fluoroacetate - the active ingredient of 1080 which is a pest animal control poison.
Wax tree or Rhus (Toxicodendron succedaneum) Highly toxic, allergy-causing tree.
Wild Carrot (Daucus carota) - can cause photo dermatitis and can be confused with Hemlock; which is highly toxic/poisonous.
Wild Radish / Wild Turnip / Wild Cabbage (Raphanus raphanistrum ssp. raphanistrum / Brassica rapa ssp. sylvestris / Brassica oleracea) All concentrate nitrates in the leaves to such an extent that they can be toxic to stock. Wild Radish seeds are toxic.
Willow Myrtle (Agonis flexuosa) From the Myrtle family, see note above.
Willow Weed (Persicaria maculosa)
Winter Heliotrope (Petasites pyrenaicus)
Wisteria ( Chinese and Japanese) All parts of the Wisteria plant are toxic.
Woolly Nightshade (Solanum mauritianum) All parts poisonous.
Yellow horned poppy (Glaucium flavum) All parts of the plant, including the seeds and the roots which are especially poisonous.
Yew (Taxus baccata) The highly toxic parts are the bark, leaves and the seeds. See note re Coniferous Trees above.
Yucca Has toxic components.
These links contain fairly extensive lists, most of which I agree with -
MediRabbit - Toxic Plants
Rabbit Advocates - Toxic Plants
House Rabbit Society - Poisonous Plants
ASPCA - Poisonous Plants