Guide to Plant Relationships

(for food allergy and intolerance identification)

Jack Campin


Version 14 (22 January 2008); the current version of this and related files can be obtained from my food intolerance and healthy eating page


Introduction

This is a list of plant groups - primarily food plants, with some medicinal plants and other species that people may come into close contact with - intended to assist people with food intolerances and allergies. In many cases, substances that cause allergy - usually proteins - are common to plants that are evolutionarily related, so knowing the evolutionary relationships can help predict when bad reactions are likely to plants you haven't tried yet.

Naming and Searching: To make these classifications precise, there is no avoiding scientific names - there are many totally unrelated plants with 'apple' in their common name, for example, and nobody is going to be allergic to all of them (allergies are caused by chemicals, not words). When searching this list for anything at all unusual, try variants of the common name, look around related plants to be sure you've got the right one, and don't stop at the first match; keep searching till you've found everything that might fit (and God help you if you can't spell; if anybody has ideas about how to do approximate searching portably in HTML browsers, get in touch).

Classifications: Generally, the closer the relationship, the more likely two plants are to have similar chemistry and produce the same sort of allergic response. But chemicals don't always occur in just one grouping - there may be isolated plants or groupings of plants with no close relationship that have evolved similar substances. Often the family level is the one that matters, but don't count on it. I've placed the families into higher-level classifications, but bear in mind that they may sometimes be of more botanical than medical relevance.

Uses: There are two intended uses for this information. Firstly, these groups are a guide to foods allergic people might have to avoid that they might not otherwise think of. Secondly, they are meant as a guide to what you can eat; to stimulate the imagination to consider fruit and vegetables that might not have occurred to you as a primary food source. All the food plants here have been eaten by whole nations for centuries - you can't ask for better testing than that. This is also the reason why I have given so much detail about closely related species and varieties - in some cases allergies may be very specific, and only one out of several plants bearing the same common name may be the one causing problems.

Hazards: Unless I have a note describing some other use for it, every entry in the list describes a food plant. Poisonous plants are all identified as such. In some cases I've added notes about possible harmful effects (to at least some people) of generally safe food plants. I'll add more of these when I get time. This is not intended to be a herbal. The notes on herbal usage are intended as cautions on prescribing; for example, a herbalist might suggest feverfew for migraine - if you also have ragweed allergy, you need to know that this might be a problem. Herbals say what to use, this says what not to. If the entry says I don't know what the plant is used for, play safe and assume it will at least make your toes fall off.

How it Works: plants are divided into six divisions: clubmosses, horsetails, ferns, cycads, ginkgos, conifers, gnetums and angiosperms (listed roughly in the order in which they first evolved). The angiosperms (by far the biggest division) split into two classes: dicotyledons (the older grouping: broadleaf plants) and monocotyledons (the more recently evolved grasses, palms and relatives). These in turn have subclasses (with a '-florae' suffix); the subclasses divide into orders (with an '-ales' suffix); orders divide into families (with an '-ae' or '-aceae' suffix); families into genuses; and genuses into species (the last two with no fixed spelling rules, except that species don't have capital letters). The genus and species together make up the botanical name of a plant, like Zea mays, maize.

Some big families can be split into subfamilies and tribes, and some species into varieties; subfamilies are notably important for the grains, Poaceae, where only one subfamily, Pooideae, has the allergen responsible for coeliac disease.

All the groupings from subclass downwards are listed alphabetically within their enclosing group, which is not the way most botany books do it. Each grouping above the genus level has a note under its title which can be clicked on to go to higher points in the classification system. I think this is the best way to show how close the relationship between any two plants is and pinpoint the scope of an allergic cross-reaction, but if anyone has a better idea I'll consider it.

Terminology: I've tried to use current botanical names for species and groupings (mostly the Cronquist system, from Stace and Mabberley), but I've often listed older names as well, since these are still current in herbals, cookbooks, and the like.

Help Needed: This is not a complete reference and it never will be. Meanwhile, some requests for further information:

  1. Any plant foods I've left out. Nothing is too obscure. If your locality makes custard out of a spiny gourd with blue flesh that grunts when you pick it, I want to know about it.
  2. Cross-family reactions to allergens that have evolved independently.
  3. Corrections to major taxonomic booboos or warnings of disputed placements.
  4. Warnings about when variations of cultivation or breeding practices make a difference relevant to allergenicity.
  5. Data on animal feeds, so as to aid prediction of when allergens may cross over into meat, eggs and milk.
  6. Some idea of which floral allergens end up in which kinds of honey.
  7. More data on plants used as feedstocks for refined food ingredients like emulsifiers, gelling agents and flavour enhancers.
  8. HTML problems with this document - misformatting or things that don't work on some browsers. I've used very few kinds of tag and only occasional special characters, but this is much bigger than most HTML documents.

Feedback: There are many substances listed below that I've never heard of anyone being allergic to, but without information like this many allergies must be going untraced; if this list helps you identify a hitherto unsuspected cross-reaction between things you didn't realize were related, I'd like to hear about it.

Language: I haven't tried to be multilingual; the common names I've given are nearly all those used in the English-speaking world (though in many cases these are not of English origin). I don't trust my ability to deal with ambiguous plant naming in every language on the planet, and I don't have a reliable informant. If you prepare versions of this in other languages, please let me know and I'll add links to them.

Scope: However, I am trying to be multicultural. People with food allergies often have to look for alternative foods from outside the culture they grew up in; and I want this to be useful over as wide a geographical area as possible. So there are many foods you've never heard of before.

Coming Soon: Similar documents about fungi and food-related microbes will be along in due course. This one only does terrestrial green plants so far; I'll add edible seaweeds in the near future.

Acknowledgements, Disclaimer and Ulterior Motives: The idea of a list like this came from Betsy Wilson (Elizabeth.Wilson@jpl.nasa.gov), but this one is far larger than hers. It would not have been possible without inspiration from Marion Bowles (marion at purr.demon.co.uk), an allergy dietitian based in Edinburgh who you can call on to help put this stuff into practice. I have no formal training in medicine or biology beyond high school. If you think you can employ someone capable of researching an unfamiliar subject unassisted and producing a document like this, give me a call.

Restrictions: Copyright Jack Campin. This file may only be redistributed complete and unchanged, except for conversions of line-termination and between character sets; no charge whatever may be made for it; any service that stores a copy of it must provide free and unrestricted access to it; it may not be included on any CD-ROM or other distribution media for which any payment is required; and professionals making use of it for any purpose that earns them money must notify their clients or patients of its existence and offer them unlimited free access to it in any case where it is consulted.

Food allergy resources on this site

My home page


Division LYCOPODIOPSIDA Clubmosses and Quillworts

Family Lycopodiaceae Clubmosses

division: Lycopodiopsida

Division EQUISETOPSIDA Horsetails

Family Equisetaceae Horsetails

division: Equisetopsida

Division CYCADOPSIDA Cycads

Family Cycadaceae

division: Cycadopsida

Division FILICOPSIDA Ferns

Order Filicales

division: Filicopsida

Family Adiantiaceae Maidenhair Fern

order: Filicales

Family Aspleniaceae Spleenwort

order: Filicales

Family Cyatheaceae

order: Filicales

Family Dryopteridaceae Buckler-Fern

order: Filicales

Family Dennstedtiaceae Bracken

order: Filicales

Order Salviniales

division: Filicopsida

Family Azollaceae

order: Salviniales

Division PINOPSIDA Conifers, Gymnosperms

Family Araucariaceae Monkey-Puzzle

division: Pinopsida

Family Cupressaceae Cypress

division: Pinopsida

Family Pinaceae Pine

division: Pinopsida

Family Taxaceae Yew


Division GINKGOOPSIDA

Family Ginkgoaceae Ginkgo

division: Ginkgoopsida

Division GNETOPSIDA

Family Gnetaceae

division: Gnetopsida

Division ANGIOSPERMS, MAGNOLIOPSIDA

Class Dicotyledons, Magnoliidae

division: Angiosperms

Subclass ASTERIFLORAE

class: Dicotyledons

Order Asterales

subclass: Asteriflorae

Family Asteraceae, Compositae Daisies

order: Asterales

Ragweed is a member of this family, and a particularly important allergen in North America; ragwort (not quite as bad) is important in Europe. This explains reactions to camomile tea in ragweed- or ragwort-sensitive people; they may also react to the insecticide pyrethrum, made from a kind of chrysanthemum.

Subfamily Asteroideae
family: Asteraceae
Tribe Anthemideae
subfamily: Asteroideae
Tribe Astereae
subfamily: Asteroideae
Tribe Calendulae
subfamily: Asteroideae
Tribe Heliantheae
subfamily: Asteroideae
Tribe Inuleae
subfamily: Asteroideae
Tribe Senecioneae
subfamily: Asteroideae
Subfamily Lactucoideae
family: Asteraceae
Tribe Cynareae
subfamily: Lactucoideae
Tribe Eupatoreae
subfamily: Lactucoideae
Tribe Lactuceae
subfamily: Lactucoideae
Tribe Vernoniae
subfamily: Lactucoideae

Order Campanulales

subclass: Asteriflorae

Family Campanulaceae

order: Campanulales

Order Dipsacales

subclass: Asteriflorae

Family Caprifoleaceae Honeysuckle

order: Dipsacales

Family Dipsacaceae Teasel

order: Dipsacales

Family Valerianaceae Valerian

order: Dipsacales

Order Gentianales

subclass: Asteriflorae

Family Apocynaceae Periwinkles, Dogbanes

order: Gentianales

Family Asclepiadaceae Milkweeds

order: Gentianales

Family Gentianaceae Gentian

order: Gentianales

Family Loganiaceae

order: Gentianales

Order Lamialales

subclass: Asteriflorae

Family Boraginaceae Borage

order: Lamialales

Family Lamiaceae, Labiatae Deadnettle

order: Lamialales

Most of this family is not presently classifiable into subfamilies.

Subfamily Lamioideae, Stachydoideae
family: Lamiaceae
Subfamily Ocimoideae
family: Lamiaceae
Subfamily not assigned
family: Lamiaceae

Family Verbenaceae Vervain

order: Lamialales

Order Plantaginales

subclass: Asteriflorae

Family Plantaginaceae Plantain

order: Plantaginales

Note that this is entirely unrelated to the banana variety also known as 'plantain'.


Order Rubiales

subclass: Asteriflorae

Family Rubiaceae Madder

order: Rubiales

Order Scrophulales

subclass: Asteriflorae

Family Acanthaceae Bear's-Breech

order: Scrophulales

Family Bignoniaceae

order: Scrophulales

Family Gesneriaceae

order: Scrophulales

Family Oleaceae Ash

order: Scrophulales

Family Orobanchaceae Broomrape

order: Scrophulales

A family of parasitic plants without chlorophyll (hence not green) used in Chinese medicine.

Family Pedaliaceae Sesame

order: Scrophulales

Family Scrophulariaceae Figwort

order: Scrophulales

Order Solanales

subclass: Asteriflorae

Family Convolvulaceae Bindweed

order: Solanales

Family Hydrophyllaceae Phacelia

order: Solanales

Family Menyanthaceae Bogbean

order: Solanales

Family Polemonaceae

order: Solanales

Family Solanaceae Nightshades

order: Solanales

Cross-reactions among all members of this family are common. Often aubergine, Solanum melongena, which is an Old World plant, does not produce cross-reactions with the other edible Solanaceae, which are from the Americas.

Honest, I have not made any of these species up.


Subclass CARYOPHYLLIFLORAE

class: Dicotyledons

Order Caryophyllales

subclass: Caryophylliflorae

Family Aizoaceae Dew-Plant

order: Caryophyllales

Family Amaranthaceae Pigweed

order: Caryophyllales

Family Basellaceae

order: Caryophyllales

Family Cactaceae Cactuses

order: Caryophyllales

Family Caryophyllaceae Pink

order: Caryophyllales

Family Chenopodeaceae Goosefoot

order: Caryophyllales

Family Nyctagenaceae Four-O'Clock

order: Caryophyllales

Family Phytolaccaeae

order: Caryophyllales

Family Portulacaceae Blinks

order: Caryophyllales

Order Polygonales

subclass: Caryophylliflorae

Family Polygonaceae Knotweed

order: Polygonales

Subclass DILLENIFLORAE

class: Dicotyledons

Order Capparales

subclass: Dilleniflorae

Family Brassicaceae, Cruciferae Cabbage

order: Capparales

Note that oilseed rape is in this family, and is a common pollen allergen in the UK.

Family Capparaceae Capers

order: Capparales

Family Moringaceae

order: Capparales

Family Resedaceae

order: Capparales

Order Dilleniales

subclass: Dilleniflorae

Family Dilleniaceae

order: Dilleniales

Family Paeonaceae

order: Dilleniales

Order Ebenales

subclass: Dilleniflorae

Family Ebenaceae Ebony

order: Ebenales

Family Sapotaceae

order: Ebenales

Family Styracaceae

order: Ebenales

Order Ericales

subclass: Dilleniflorae

Family Ericaceae Heather

order: Ericales

Order Lecythidales

subclass: Dilleniflorae

Family Lecythidaceae

order: Lecythidales

Order Malvales

subclass: Dilleniflorae

Family Bombacaceae

order: Malvales

Family Malvaceae Mallow

order: Malvales

Family Sterculiaceae

order: Malvales

Family Tiliaceae Lime

order: Malvales

Order Primulales

subclass: Dilleniflorae

Family Primulaceae

order: Primulales

Order Salicales

subclass: Dilleniflorae

Family Salicaceae

order: Salicales

Order Theales

subclass: Dilleniflorae

Family Actinidiaceae Kiwifruit

order: Theales

Family Camelliaceae, Theaceae Camellias

order: Theales

Family Caryocaraceae

order: Theales

Family Clusiaceae, Guttiferae, Hypericaceae

order: Theales

Family Dipterocarpaceae

order: Theales

Order Violales

subclass: Dilleniflorae

Family Bixaceae

order: Violales

Family Caricaceae Papaya

order: Violales

Family Cucurbitaceae Marrows

order: Violales

Family Flacourtiaceae

order: Violales

Family Passifloraceae Passion Fruit

order: Violales

Family Turneraceae

order: Violales

Family Violaceae Violets

order: Violales

Subclass HAMAMELIFLORAE

class: Dicotyledons

Order Eucommiales

subclass: Hamameliflorae

Family Eucommiaceae

order: Eucommiales

Order Fagales

subclass: Hamameliflorae

Family Betulaceae Birches

order: Fagales

Family Corylaceae Hazel

order: Fagales

Family Fagaceae Beech

order: Fagales

Order Hamamelidales

subclass: Hamameliflorae

Family Hamamelidaceae

order: Hamamelidales

Order Juglandales

subclass: Hamameliflorae

Family Juglandaceae Walnut

order: Juglandales

Order Myricales

subclass: Hamameliflorae

Family Myricaceae

order: Myricales

Order Urticales

subclass: Hamameliflorae

Family Cannabaceae Cannabis

order: Urticales

Family Moracae Mulberry

order: Urticales

Family Ulmaceae Elms

order: Urticales

Family Urticaceae Nettles

order: Urticales

Dead Nettle, Lamium album is unrelated to any of these.


Subclass MAGNOLIIFLORAE

class: Dicotyledons

Order Aristolochiales

subclass: Magnoliiflorae

Family Aristolochaceae

order: Aristolochiales

Order Illiciales

subclass: Magnoliiflorae

Sometimes merged with the Magnoliales.

Family Illiciaceae

order: Illiciales

Family Schisandraceae

order: Illiciales

Order Laurales

subclass: Magnoliiflorae

Family Lauraceae Laurel

order: Laurales

Family Monimiaceae

order: Laurales

Order Magnoliales

subclass: Magnoliiflorae

Family Annonaceae Custard Apple

order: Magnoliales

Family Canellaceae, Winteranaceae

order: Magnoliales

Family Magnoliaceae Magnolias

order: Magnoliales

Family Myristaceae Nutmeg

order: Magnoliales

Order Nympheales

subclass: Magnoliiflorae

Family Nymphaeaceae Water Lilies

order: Nympheales

Order Papaverales

subclass: Magnoliiflorae

Family Fumariaceae Fumitory

order: Papaverales

Family Papaveraceae Poppies

order: Papaverales

Order Piperales

subclass: Magnoliiflorae

Family Piperaceae Pepper

order: Piperales

Family Saururaceae

order: Piperales

Order Ranunculales

subclass: Magnoliiflorae

Family Berberidaceae

order: Ranunculales

Family Lardizabalaceae

order: Ranunculales

Family Menispermaceae

order: Ranunculales

Family Ranunculaceae Buttercup

order: Ranunculales

Subclass ROSIFLORAE

class: Dicotyledons

Order Apiales

subclass: Rosiflorae

Family Apiaceae, Umbelliferae Umbellifers, Carrot

order: Apiales

Family Araliaceae

order: Apiales

Order Celastrales

subclass: Rosiflorae

Family Aquifoliaceae Holly

order: Celastrales

Family Celastraceae

order: Celastrales

Family Corynocarpaceae

order: Celastrales

Family Pandanaceae

order: Celastrales

Order Cornales

subclass: Rosiflorae

Family Cornaceae Dogwood

order: Cornales

Order Euphorbiales

subclass: Rosiflorae

Family Buxaceae Box

order: Euphorbiales

Family Euphorbiaceae

order: Euphorbiales

Family Simmondsaceae

order: Euphorbiales

Order Fabales

subclass: Rosiflorae

The three families in this order are sometimes regarded as subfamilies of the single family Leguminosae. The order as a whole is related to the Sapindales.

Family Caesalpinaceae

order: Fabales
Subfamily Caesalpineae
family: Caesalpinaceae
Subfamily Cassieae
family: Caesalpinaceae
Subfamily Cercideae
family: Caesalpinaceae
Subfamily Detarieae
family: Caesalpinaceae

Family Leguminosae Peas, Beans, Legumes

order: Fabales
Subfamily Abreae
family: Leguminosae
Subfamily Aeschynomeneae
family: Leguminosae
Subfamily Cicereae
family: Leguminosae
Subfamily Coronilleae
family: Leguminosae
Subfamily Crotalarieae
family: Leguminosae
Subfamily Dalbergiae
family: Leguminosae

This subfamily contains gum and phenolics.

Subfamily Desmodieae
family: Leguminosae

Members of this family contain canavanine.

Subfamily Dipteryxeae
family: Leguminosae
Subfamily Galegeae
family: Leguminosae

Members of this family usually contain canavanine.

Subfamily Genisteae
family: Leguminosae
Subfamily Hedysareae
family: Leguminosae
Subfamily Indigoferae
family: Leguminosae
Subfamily Lateae
family: Leguminosae

This subfamily contains canavanine.

Subfamily Millettiae
family: Leguminosae
Subfamily Phaseolae
family: Leguminosae
Subfamily Sophoreae
family: Leguminosae
Subfamily Thermopsideae
family: Leguminosae
Subfamily Trifoleae
family: Leguminosae
Subfamily Trifoleae
family: Leguminosae

Family Mimosaceae

order: Fabales
Subfamily Acaciae
family: Mimosaceae
Subfamily Ingeae
family: Mimosaceae
Subfamily Mimoseae
family: Mimosaceae
Subfamily Parkiae
family: Mimosaceae

Order Geraniales

subclass: Rosiflorae

Family Balsaminaceae

order: Geraniales

Family Geraniaceae

order: Geraniales

Family Oxalidaceae Oxalis

order: Geraniales

Family Tropaeolaceae

order: Geraniales

Family Zygophyllaceae Caltrop

order: Geraniales

Order Linales

subclass: Rosiflorae

Family Erythroxylaceae Coca

order: Linales

Family Linaceae Flax

order: Linales

Order Myrtales

subclass: Rosiflorae

Family Combretaceae

order: Myrtales

Family Lythraceae Loosestrife

order: Myrtales

Family Myrtaceae Myrtles

order: Myrtales

Family Onagraceae Willowherb

order: Myrtales

Family Punicaceae Pomegranate

order: Myrtales

Order Polygalales

subclass: Rosiflorae

Family Krameriaceae

order: Polygalales

Family Malpighiaceae

Family Polygaleae

order: Polygalales

Order Proteales

subclass: Rosiflorae

Family Elaeagnaceae Oleaster

order: Proteales

Family Proteaceae

order: Proteales

Order Rhamnales

subclass: Rosiflorae

Family Rhamnaceae

order: Rhamnales

Family Vitaceae Vines

order: Rhamnales

Order Rosales

subclass: Rosiflorae

Family Crassulaceae

order: Rosales

Family Grossulariaceae Currant, Saxifrage

order: Rosales

Family Rosaceae Roses

order: Rosales

Order Santalales

subclass: Rosiflorae

Family Santalaceae Sandalwood

order: Santalales

Family Simaroubaceae

order: Santalales

Family Viscaceae

order: Santalales

Order Sapindales

subclass: Rosiflorae

This order is related to the Fabales.

Family Aceraceae

order: Sapindales

Family Anacardiaceae Cashew

order: Sapindales

Almost all plants of this family produce saps which may be violently irritant. The family includes the Malayan Rengas trees and the American Poison Ivy. Cross-reactions among members of this family are common.

Family Burseraceae

order: Sapindales

Family Hippocastanaceae Horse Chestnut

order: Sapindales

Family Meliaceae

order: Sapindales

Family Rutaceae Rue

order: Sapindales

Family Sapindaceae Lychees

order: Sapindales

Class Monocotyledons, Liliidae

division: Angiosperms

Subclass ALISMATIFLORAE

class: Monocotyledons

Order Najadales

subclass: Alismatiflorae

Family Apogonetonaceae Flowering Rush

order: Najadales

Family Zosteraceae

order: Najadales

Subclass ARECIFLORAE

class: Monocotyledons

Order Arales

subclass: Areciflorae

Family Araceae Arums

order: Arales

Note that several different taro species may be fermented to make 'poi' in Polynesia.


Order Arecales

subclass: Areciflorae

Family Arecaceae, Palmae Palms

order: Arecales

Sago comes from several different species of palm tree.


Subclass COMMELINIFLORAE

class: Monocotyledons

Order Cyperales

subclass: Commeliniflorae

Family Cyperaceae Sedges

order: Cyperales

Family Poaceae, Gramineae Grasses

order: Cyperales
Subfamily Arundinoideae
family: Poaceae
Tribe Arundineae
subfamily: Arundinoideae
Subfamily Bambusoideae
family: Poaceae
Tribe Bambuseae
subfamily: Bambusoideae
Tribe Oryzae
subfamily: Bambusoideae
Subfamily Chloridoideae
family: Poaceae
Tribe Eragrostideae
subfamily: Chloridoideae
Subfamily Panicoideae
family: Poaceae
Tribe Andropogoneae
subfamily: Panicoideae
Tribe Paniceae
subfamily: Panicoideae
Subfamily Pooideae
family: Poaceae

Gluten (the allergen responsible for coeliac disease and dermatitis hepetiformis) is only found in grains in this subfamily - the most commonly problematic forms are in the tribe Triticeae, but some people react to the Aveneae as well.

Tribe Aveneae
subfamily: Pooideae
Tribe Agrostideae
subfamily: Pooideae
Tribe Triticeae
subfamily: Pooideae
Tribe Poeae
subfamily: Pooideae

Order Juncales

subclass: Commeliniflorae

Family Juncaceae

order: Juncales

Subclass LILIIFLORAE

class: Monocotyledons

Order Liliales

subclass: Liliiflorae

Family Agavaceae

order: Liliales

Family Dioscoraceae Yams

order: Liliales

Family Iridaceae Irises

order: Liliales

Family Liliaceae Lily

order: Liliales

Family Pontederiaceae

order: Liliales

Family Smilaceae Smilax

order: Liliales

Family Taccaceae

order: Liliales

Order Orchidales

subclass: Liliiflorae

Family Orchidae Orchids

order: Orchidales

Subclass ZINGIBERIFLORAE

class: Monocotyledons

Order Bromeliales

subclass: Zingiberiflorae

Family Bromeleaceae Bromeliads

order: Bromeliales

Order Zingiberales

subclass: Zingiberiflorae

Family Cannaceae Cannas

order: Zingiberales

Family Marantaceae Arrowroot

order: Zingiberales

Family Musaceae Bananas

order: Zingiberales

Family Strelitziaceae

order: Zingiberales

Family Zingiberaceae Ginger

order: Zingiberales

A Plant I Don't Have Any Name For

A cherry-like fruit confined to the Trabzon area of Turkey. Unlike a normal cherry, the fruit are not on paired stalks, but shorter and thicker stalks that attach more firmly to the parent twig. Slightly larger than a cherry; tastes like a black cherry but less sweet and with a tougher and darker skin. I presume it's in the plum/cherry genus but I'd like a name for it.


Cross-Reactions from Non-Food Allergens

Many allergies can be triggered by both food and non-food items, where there is a chemical similarity that makes the immune system respond in the same way - either they contain the same chemicals or a similarity in the shape of parts of the two molecules fools your immune system into thinking they're the same. Here are a few of these links.

Pollens

The following table is from Brostoff and Gamlin's Hayfever. The commonest cross-reactant is listed first.

Birch
Apple, Carrot, Cherry, Pear, Peach, Plum, Fennel, Walnut, Potato, Spinach, Wheat, Buckwheat, Peanut, Honey
Mugwort
Celery, Carrot, Spices, Melon, Watermelon, Apple, Camomile
Grass
Melon, Tomato, Watermelon, Orange, Swiss Chard
Pellitory
Cherry, Melon
Ragweed
Melon, Camomile, Honey, Banana, Sunflower seeds
Pine
Pine Nut
Hazel
Hazel Nut

Other Stuff

House Dust Mite
Kiwifruit, Papaya
Latex
watch this space

Plant Sources of Processed Foods and Food Additives

Just the beginning of a much larger section...

Bromelain
Pineapple
Caramel
Sugar
Chymopapain
Papaya
Corn Syrup
Corn
Crocin (food colouring: the substance also found in saffron)
Gardenia jasminoides
Dextrin
Corn, Potato, Tapioca
Guar Gum
Guar
Lecithin
Soya, Corn, Cotton Seed, Rape, Sunflower, Egg
Lutein
Aztec Marigold, Alfalfa
Malt
Barley
Maltol
Larch trees, pine needles
Papain
Papaya
Stearate, Stearic Acid
may be of animal origin or produced by hydrogenating vegetable oils, e.g. cottonseed oil
Tofu
Soya

Chemicals Common to Many Foods

Just the beginning of a much larger section...

Benzoic Acid
Berries, Cherry Bark, Cranberry, Prunes, Anise, Clove, Cassia, Cinnamon, Tea
Diacetyl
Cheese, Cocoa, Coffee, Berries, Pears
Malic Acid
Apple, Cherry, Peach, Tomato, Rhubarb, Pear, Plum, Berries
Oxalic Acid
Blackberry (trace), Grapefruit, Grape, Lemon, Lime, Orange, Pear, Plum, Broccoli, Potato, Rhubarb, Tomato
Palmitic Acid
Butter, Celery (seed), Palm Oil, Coffee, Tea, Anise (seed), herbs (seed)
Quinine
Cinchona, Grapefruit (pith)
Salicylate
Apple, Almond, Apricot, Berries, Plum, Prune, Grape, Cucumber, Clove, Wintergreen, Tomato, White Willow (bark)
Sorbic Acid
Mountain Ash
Sorbitol
Apple, Berries, Cherry, Pear, Plum
Tannic Acid, Tannate
Coffee, Tea, Palm (seed pods), Oak (bark, galls), Cherry (bark), Sumac (bark), Ferns
Tartaric Acid, Tartrate
Grape, Coffee

References

The following happen to be the sources I've used in this. All are either out of print or obscure and most are both. Sorry.

P.V. Bole and Yogini Vaghani, Field Guide to the Common Trees of India, Oxford University Press and World Wildlife Fund (India), 1991

Lesley Bremness, Herbs, Dorling Kindersley, 1994

Jonathan Brostoff and Linda Gamlin, Hayfever, Parragon, London 1994

D. G. Coursey, Yams, Longman (Tropical Agriculture Series), 1967

L.M. Cranwell, J.E. Green, and A.W.B. Powell, Food Is Where You Find It: a guide to emergency foods of the Western Pacific, Auckland Institute and Museum, 1944

Daniel E. Efron (editor), Ethnopharmacologic Search for Psychoactive Drugs, National Institute of Mental Health (US Department of Health, Education, and Welfare), 1967

Bob Flowerdew, Bob Flowerdew's Complete Fruit Book, Kyle Cathie, 1995

S.G. Harrison, G.B. Masefield, Michael Wallis and B.E. Nicholson, The Oxford Book of Food Plants, Oxford University Press, 1969 and Peerage Books, 1985

J. Hutchinson, The Families of Flowering Plants - I. Dicotyledons, Macmillan, 1926

Stewart Johnson, Feverfew, Sheldon Press, 1984

John Lust, The Herb Book, Bantam, 1974

D.J. Mabberley, The Plant-Book, Cambridge University Press, 1992

Cass McCallum, The Real Food Guide: v.1 Fresh Fruit and Vegetables, v.2 Pulses, Seeds and Grains, Molendinar/Richard Drew, 1981

Prosper Montagné, Larousse Gastronomique, Paul Hamlyn, 1961

J.L. Newman, Dimensions of Sandawe Diet, in Robson

Sri Owen, Indonesian Food and Cookery, Prospect Books, 1985

Jean Palaiseul, Grandmother's Secrets, Penguin, 1973

Andrew M. Pope, Roy Patterson, Harriet Burge (editors), Indoor Allergens: Assessing and Controlling Adverse Health Effects, National Academy Press, 1993

Christian Rätsch, The Dictionary of Sacred and Medicinal Plants, Prism, 1992

K.W. Riley, N. Mateo, G.C Hawtin, and R. Yadav (editors), Mountain Agriculture and Crop Genetic Resources, Aspect, 1990

J.R.K. Robson, Food, Ecology and Culture: Readings in the Anthropology of Dietary Practices, Gordon and Breach, 1980

G.M. de Rougemont, A Field Guide to the Crops of Britain and Europe, Collins, 1989

Jim Smith (editor), Food Additive User's Handbook, Blackie, 1991

Solomon H. Snyder and Malcolm H. Lader, Flowering Plants: Magic in Bloom, (part of The Encyclopedia of Psychoactive Drugs), Burke, 1986

Clive Stace, New Flora of the British Isles, Cambridge University Press, 1991

Stafford Allen and Sons, The Romance of Empire Drugs, 1930s?

Maguelonne Toussaint-Samat, History of Food, Blackwell, 1994

Legal Highs, Twentieth Century Alchemist, 1973

Colin Tudge, Food Crops for the Future, Blackwell, 1988

Harold Ward, Herbal Manual, C.W. Daniel, 1946

R.E. Wright-St Clair, Diet of the Maoris of New Zealand, in Robson


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