7

IntroductionMost gardeners are familiar with the Latin names for plants, even if they do not like using them. What they may also notice on labels in public gardens, as well as in the RHS Plant Finder, are the family names, which end in -aceae. The family is the next main rank above that of genus and is the means to indicate that genera belonging to the same family are more similar to each other than to those that belong in another family. This is part of a botanical hierarchy used to organise plants into an overall system of relatedness, generally referred to as a classification. Man has been classifying plants since at least Theophrastus (c. 300bc) and our current system dates back to Linnaeus (1753), who introduced the concept of the binomial (genus and species name) as well as the arrangement of plants according to their flower structure. Both concepts have dominated our thinking about how we name and classify plants although, over time, we have been able to find different ways of collecting information about plants, and different kinds of data with which to test our classifications. The most recent of these techniques has been the analysis of genetic material (genome) and this has been applied to plants as much as it has to other kinds of organisms. The results of analysing many thousands of different plants have brought about a new understanding of plant relationships and, consequently, a major reclassification of plants, and flowering plants (angiosperms) in particular.

The new classification is known by the acronym APG (Angiosperm Phylogeny Group) which refers to the international team of scientists that have been carrying out the analysis of plant genetic material over the past 15 to 20 years. There have been three classifications published (APG, 1998, 2003 and 2009), generally known as APG, APG II and APG III. While the work has been known about for some time it is only really over the past five years that its impact has begun to be felt more widely, with major institutions such as the Royal Botanic Gardens, Kew and Edinburgh adopting the APG system for their herbaria and plant labelling. A recent Plant Network conference (www.plantnetwork.org/proceeds/wales2009/summary.htm) showed how the new system is being taken up in public gardens in the UK (Latta, 2008; Horticulture Week, 7 August 2009). In view of this, the RHS’s Advisory Committee on Nomenclature and Taxonomy took the decision that it was appropriate for the RHS to adopt the classification as presented in the latest edition of

Mabberley’s Plant-book (2008) for use in the RHS horticultural database, from which the RHS Plant Finder is produced as well as the labels for plants in our gardens. This is broadly the same as the classification presented in the latest version of the APG classification (APG, 2009) and the differences are shown in the table with this article.

The importance of classificationA classification is, in the most abstract sense, a method of organising information. It has at least two functions: to enable communication, as such names are a shorthand to indicate relationships, and to predict, in that in associating entities you should be able to ascertain the properties of one entity from its position in the classification. It should also be possible to incorporate new information. For plants, as for any other living organisms, that element of predictiveness means that the basis for the classification must be genetic relatedness (or shared descent). Although Linnaeus’s most famous classification, which is predictive, is not based on relatedness, only shared characters, even Linnaeus realised its artificiality and drew up a parallel system based on what he thought was a more natural arrangement. In the context of classification the word natural is normally used to mean that it is based on relatedness. Linnaeus, of course, classified organisms over 100 years before Darwin published his book On the Origin of Species by Means of Natural Selection, which revolutionised the theoretical basis of classification. It took a while for the first classifications based on his theory of evolution to be produced but ever since almost every classification published represents the classifier’s concept of evolutionary relationships.

The consequence of this is that every scientific name we use conveys some information about the plant’s relationships. The basic unit is the species, and these are clustered together in genera so that those that are most closely related belong in the same genus, those more distantly related will belong in other genera, which in turn are brought together in families and so on, in a hierarchy that ultimately reaches the level of Kingdom (such as Plantae, or Plants). It is this premise of a plant’s relationships being revealed through its name and classification that is one source for name changes. As relationships are better understood, so it is necessary to change the position of the plant and this will generally lead to a change in name. While this is so, it is also widely accepted that such classifications are

Plants in their proper places

Plants in their proper places – the new classification of flowering plants

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hypotheses and that the categories in which we arrange organisms are artificial constructs. In nature there are no genera or families or orders: some argue that species are real but as Linnaeus said, ‘nature does not make leaps’, or to put it another way, when you look at the individuals and populations that make up plants that you are studying, it is often hard to see where the divisions lie or whether those divisions are there at all.

This explanation attempts to show why classifications matter and, in particular, why the APG classification and the changes it is making to plant labels and information about plants matter to gardeners. By and large the new classification does not affect the genera – although these also are being changed by the application of molecular methods – but does make significant differences at the levels of family and above. While molecular data have confirmed many previously recognised relationships based on morphological characters, what has been fascinating is where families not previously thought to be close together have been found to be closely related. This has in many cases subsequently brought to light other features such as plant chemistry and microscopic characters, generally far less prone to rapid evolutionary change than those features we have traditionally relied on, like the flower, that support the new classification. Molecular data have also shown that our concepts of what are early evolving plants and which have a more recent origin need to change. This too affects the classification as early evolving plants are customarily placed at the beginning of a linear sequence of a classification, while those that appeared later are at the end.

A survey of the new systemA long-standing fundamental division of flowering plants is based on the number of seed leaves, and the groups thus distinguished are known as monocotyledons (one seed-leaf ) and dicotyledons (two seed-leaves). While the molecular data show that the monocotyledons are a natural group, they are found to have arisen from an ancestor with two seed-leaves and so do not have a separate origin to the dicots. It also shows that the earliest diverging flowering plants are dicotyledonous in the traditional sense of the word. It is of interest that this relationship is borne out by the structure of the pollen: the monocots and those dicots that arose before the monocot-dicot divergence all have pollen grains with either a single pore or single groove; the later dicots (or eudicots) all have pollen grains based on the three-pore or three-groove pattern.

The living flowering plant which diverged first has been found to be a woody shrub (Amborella) which is endemic to New Caledonia. While it had always been regarded as being among the early arising dicots, it had not been thought to be as

significant in flowering plant evolution as the molecular data now indicate. It may be something of a surprise that the water lilies are next in the sequence, given the apparent complexity and conspicuousness of their flowers. However, water lilies (Nymphaeaceae) are beetle-pollinated and it has been observed that many of the earliest flowering plants are beetle-pollinated; a reflection of the co-evolution of flowers and many insect groups. It turns out that beetles are amongst the earliest insect groups to evolve, and that flower pollination, and thus flower structure, has co-evolved with the insect pollinators, as insect diversity increased rapidly alongside flowering plant diversity. Also amongst the cluster of early diverging angiosperms is another group of woody plants and of these the best known to gardeners are Illicium (allspice) and Schisandra in the family Schisandraceae.

Next in the sequence and still before the divergence of the monocots is a group of predominantly woody, tropical plants characterised by Magnolia. Those familiar with previous classifications will be aware that Magnolia and its allies were thought to be the earliest flowering plants to arise due to their relatively unspecialised floral morphology. In addition to Magnolia, also included in this group are Drimys (Winteraceae), Aristolochia and Asarum (Aristolochiaceae), Peperomia (Piperaceae), Chimonanthus (Calycanthaceae), Laurus and Persea (Lauraceae) and the nutmeg (Myristica, Myristacaceae).

It is after this point that the monocots and dicots diverge and the remainder of the dicots are informally referred to as the eudicots. It is amongst this group that we start to see the differentiation of perianth segments into petals and sepals, although this is not universal and many eudicot flowers are much reduced or adapted and have lost this feature. The first eudicot group to arise is that which is represented by the paradigm of flower morphology, Ranunculus. Closely related are Berberis and Mahonia (Berberidaceae), and the poppies (Papaveraceae, which also includes Corydalis and Dicentra). It is the next group, however, which probably causes one of the biggest surprises. Associated together are three families of very different appearance: another group of water lilies (Nelumbo), the planes (Platanaceae) and the proteas (Proteaceae). While there are no obvious features that all three types of plant share, there are some characteristics that link the planes and the proteas particularly, most notably the stipules that surround the stem. Also among the early diverging eudicots is the box family, Buxaceae, which in previous classifications was thought to be closer to the Euphorbiaceae.

This brings us to the group referred to as the “core eudicots” amongst which the arrangement of flower parts in fives is the basic plan, although as with the differentiation of the perianth, there are many variations in form where this basic plan is not

Plants in their proper places

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evident. At the bottom of the core eudicots, sister to all the rest is Gunnera (Gunneraceae), the flower parts of which are still in twos. Next to the gunneras comes a large group around the Saxifragaceae which brings together families which had never previously been associated, such as Cercidophyllum (Cercidophyllaceae); Crassula (Crassulaceae); Ribes (Grossulariaceae); Hamamelis and Corylopsis (Hamamelidaceae); Itea (Iteaceae) and Paeonia (Paeoniaceae). This highly diverse group appears to have evolved rapidly towards the middle of the Cretaceous and, as yet, no single uniting characteristic has been identified.

At this point the eudicots divide into two major lineages, the rosids and the asterids. Broadly this reflects the organisation of the perianth into those with separate petals and those where the petals are fused, at least partially, into a tube. Earlier botanists referred to these two groups as Polypetalae and Gamopetalae respectively so it is fascinating to see this reflected in the results from molecular analysis. Amongst the rosids there are some more surprises: the previously unsuspected relationship between the euphorbias (Euphorbiaceae), the passion flowers (Passifloraceae), the willows (Salicaceae), the violets (Violaceae) and the tropical parasite with the largest solitary flower, Rafflesia. Initially unexpected was the revelation that the families related to the roses (Rosaceae) are Cannabis (Cannabaceae), Elaeagnus (Elaeagnaceae), the elms (Ulmaceae) and the nettles (Urticaceae). The striking difference in appearance of the flowers is largely due to wind pollination, which favours reduced flowers with small petals or no petals at all, a feature not unknown in the Rosaceae (e.g. Sanguisorba, Polylepis).

While all these surprises might bring one to question whether the molecular data are reliable as a foundation for classification, or that errors may have crept into the analysis, it should be pointed out that this work has been carried out on many representatives of each family and for up to six different regions of the genome. Although there are some discrepancies, and these are still the subject of debate (leading to some plants still being “unplaced” in the classification), most of the results are consistent and therefore give confidence that these are giving a more accurate picture of relationships.

Another cluster is the group of families which all share the chemical feature of producing mustard oils, distinctive for the pungent smell plants in these families give off, especially if crushed. Although the presence of mustard oils has been known for some time, it was not until the molecular data showed that the plants that produce these oils are related that the significance of the oils for plant classification was fully appreciated. This grouping includes the cabbage family (Brassicaceae), the capers (Capparaceae), the paw paws (Caricaceae),

Cleome (Cleomaceae) and the nasturtiums (Tropaeolaceae). Shared chemistry is also to be found in the group of families related to the pinks (Caryophyllaceae) which also includes the ice plants (Aizoaceae), the cacti (Cactaceae), pokeweeds (Phytolaccaceae) as well as spinach and beets (Chenopodiaceae); to these have been added, on molecular evidence, many of the families of carnivorous plants (e.g. Droseraceae and Nepenthaceae) as well as the sea heath (Frankeniaceae) and tamarisk (Tamaricaceae).

In the other main lineage, the asterids, there are two early diverging groups: one around the Cornaceae which, unexpectedly, proves to be closer to the Hydrangeaceae than indicated by floral morphology; the other, a large cluster around the Ericaceae which itself now includes the Epacridaceae, Empetraceae and Pyrolaceae. This cluster contains families long known to be related but also the phlox family (Polemoniaceae) and the pitcher plants (Sarraceniaceae). A contentious issue in APG I and II has been the boundary between the Primulaceae and the Myrsinaceae, the latter being largely tropical shrubs and trees; however, under the current classification these have been merged into one family, Primulaceae.

It is amongst the core asterids that some major families of horticulturally important plants are to be found and one of the most keenly debated questions has been the fate of the foxglove family (Scrophulariaceae). Whereas in many cases the molecular data have indicated that families might be merged together, it is quite the reverse in the Scrophulariaceae where some former members are, according to APG II and III, placed in new or different families, such as Calceolariaceae (Calceolaria), Paulowniaceae (Paulownia) or Phrymaceae (Mimulus). The greatest upheaval is, perhaps, the transfer of many genera, such Antirrhinum, Digitalis and Hebe to the Plantaginaceae, previously a small family of predominantly wind-pollinated plants. What remains in the Scrophulariaceae are a few of the original genera, such as Verbascum and Phygelius, together with others not originally thought to belong there including Buddleja and Myoporum. While at first this may seem an unlikely rearrangement, it should be remembered that the Scrophulariaceae were never well defined morphologically.

A similar situation arises with the systematics of the honeysuckle family (Caprifoliaceae), which in an earlier version was broken up into a number of different families. In the latest treatment (APG III), they have all been combined, together with the teasel family (Dipsacaceae) and the valerians (Valerianaceae), into one family, Caprifoliaceae, with the exception of Sambucus and Viburnum. These have been referred to the Adoxaceae, a family originally of small herbaceous woodland plants.

Plants in their proper places

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10 Plants in their proper places

Some may be surprised by the appearance of the umbellifers (Apiaceae and the closely related family Araliaceae) among the asterids alongside Pittosporum and Griselinia. Also notable is Escallonia, traditionally considered to be closely related to the currants (Grossulariaceae) and broadly associated with the roses, which now comes out as a distinctive lineage among the asterids.

As mentioned above, the monocots have been recognised as being a natural group, as defined by the possession of one seed leaf, in the APG classification, but changes to relationships within the group have been proposed. The principal horticultural groups are the aroids, the palms, the grasses, bromeliads, gingers, orchids and the diverse cluster of bulbous, cormous or rhizomatous monocot plants. These latter have been treated in many different ways, from a broadly circumscribed Liliaceae to a large number of much smaller families (Hyacinthaceae, Convallariaceae, etc.). Molecular data have helped to resolve many of these uncertainties and, as with the dicots, have pointed out a number of more unexpected groupings.

The earliest diverging monocot lineage has been found to be that leading to Acorus (sweet flag), previously thought to be a member of the Araceae (Arum family) and it is perhaps interesting to observe that among the early diverging monocots, the majority are aquatic. Other distinctive groups of monocots such as the palms (Arecaceae) and the gingers (Zingiberaceae) are still recognised, although the pineapple family (Bromeliaceae) has been revealed to be much more closely related to the grasses (Poaceae) than previously thought.

Molecular data have helped greatly to improve our understanding of the bulbous petaloid monocotyledons and given greater significance to a character, the nature of the seed coat, which had not formerly been seen to be of importance. In this group of plants there are two types of seed coat; one type has a dark, non-cellular covering, the other has a pale, cellular covering. This distinction neatly fits with the molecular data, and consequently two main groups are recognised: the asparagoids (Asparagales) with dark-coated seeds, and the lilioids (Liliales) with pale-coated seeds. The Liliaceae is now circumscribed as a much smaller group of genera, including Lilium, Tulipa, Fritillaria, Erythronium and Tricyrtis; while Disporum, Uvularia and Colchicum are now in the Colchicaceae.

The other main cluster, the asparagoids, includes an unchanged Iridaceae and Amaryllidaceae, which may be expanded to include Agapanthus and the Alliaceae (onions). Many of the genera formerly included in Liliaceae are now placed in an enlarged Asparagaceae, such as Convallaria, Ornithogalum, Scilla, Agave, Cordyline, Polygonatum and Ruscus. Phormium and Hemerocallis come together in the

Hemerocallidaceae. The orchids, however, long held to be an isolated group among the monocots, are now shown to belong among the asparagoids, reflecting the over-emphasis given in previous classifications to conspicuous floral features of this highly adapted group of plants.

Further researchAs has been observed on a number of points in this piece, the more startling rearrangements revealed by molecular analysis often lack the shared characteristics that would enable recognition by more traditional means. The task now is to re-examine the many kinds of data available to characterise plants to see which one or ones fit the molecular data. These will vary from group to group as evolution is driven by different pressures over time. Further, there are still uncertainties in the position of some groups, such as the Boraginaceae, and these questions are still being worked on, so further changes can be expected, although these will be relatively minor. As this research continues and new information comes to light, these are incorporated in the Angiosperm Phylogeny Website (www.mobot.org/MOBOT/Research/APweb/welcome.html). This is an invaluable resource for anyone interested in finding out more. For those that prefer their information in print, the standard reference is the third edition of Mabberley’s Plant-book but the updated edition of Heywood et al. (Flowering Plants of the World) is also based on APG, although it diverges significantly in the treatment of certain families.

Dr John DavidRHS Chief Scientist

ReferencesAngiosperm Phylogeny Group (1998). An Ordinal Classification for the Families of Flowering Plants. Annals of the Missouri Botanical Garden 85: 531–553.Angiosperm Phylogeny Group (2003). An Update of the Angiosperm Phylogeny Group Classification for the Orders and Families of Flowering Plants: APG II. Botanical Journal of the Linnean Society 141: 399–436.Angiosperm Phylogeny Group (2009). An Update of the Angiosperm Phylogeny Group Classification for the Orders and Families of Flowering Plants: APG III. Botanical Journal of the Linnean Society 161: 105–121.Heywood, V.H., Brummitt, R.K., Culham, A. & Seberg, O. (2007). Flowering Plant Families of the World. Kew, RBG Kew.Latta, J. (2008). Changing to APG II – Theory Put into Practice. Sibbaldia 6: 133–153.Mabberley, D.J. (2008). Mabberley’s Plant-book. Third Edition. Cambridge, CUP.

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Only those families with one or more representative genera in cultivation are given. Groups in square brackets are ones for which there are no representatives in UK horticulture.

Subclass Magnoliidae[Superorder Amborellanae]

Superorder NymphaeanaeOrder Nymphaeales

Family Nymphaeaceae (Nymphaea)

Superorder AustrobaileyanaeOrder Austrobaileyales

Family Schizandraceae (Schisandra, Illicium)Order Chloranthales

Family Chloranthaceae (Chloranthus)

Superorder MagnolianaeOrder Canellales

Family Winteraceae (Drimys, Pseudowintera)Order Piperales

Family Aristolochiaceae (Aristolochia, Asarum)Family Saururaceae (Saururus)

Order MagnolialesFamily Annonaceae (Asimina)Family Magnoliaceae (Magnolia, Liriodendron)

Order LauralesFamily Atherospermataceae (Atherosperma,

Laurelia)Family Calycanthaceae (Chimonanthus,

Calycanthus)Family Lauraceae (Laurus, Lindera, Neolitsea,

Sassafras)

MonocotsSuperorder Lilianae

Order AlismatalesFamily Acoraceae1 (Acorus)Family Araceae (Arum, Dracunculus, Arisaema,

Zantedeschia, Lysichiton)[Order Petrosaviales]Order Dioscoreales

Family Dioscoreaceae (Dioscorea, Tacca)Order Pandanales

Family Pandanaceae (Pandanus)Order Liliales

Family Alstroemeriacae (Alstroemeria, Bomarea)Family Colchicaceae (Colchicum, Disporum,

Uvularia, Gloriosa)

1 Treated as a separate order, Acorales in APG III

Family Liliaceae (Lilium, Erythronium, Fritillaria, Tulipa)

Family Melanthiaceae (Veratrum, Paris, Trillium)Family Philesiaceae (Philesia, Lapageria)Family Smilacaceae (Smilax)

Order AsparagalesFamily Amaryllidaceae (Amaryllis, Narcissus,

Galanthus, Sternbergia, Crinum) Family Alliaceae2 (Allium, Tulbaghia,

Nectaroscordum)Family Agapanthaceae2 (Agapanthus)Family Asparagaceae (Agave, Hosta, Yucca,

Cordyline, Convallaria, Polygonatum, Ruscus, Asparagus, Triteleia, Scilla, Hyacinthus, Ornithogalum, Eucomis, Dianella)

Family Asteliaceae (Astelia)Family Hypoxidaceae (Rhodohypoxis)Family Iridaceae (Iris, Gladiolus, Moraea,

Sisyrinchium, Crocus, Watsonia, Crocosmia, Dierama)

Family Ixoliriaceae (Ixolirion) Family Orchidaceae (Bletilla, Cypripedium,

Dactylorhiza, Pleione, Dendrobium)Family Tecophilaeaceae (Tecophilaea)Family Hemerocallidaceae3 (Hemerocallis,

Phormium)Family Asphodelaceae3(Asphodeline,

Kniphofia, Eremurus, Aloe, Gasteria)Family Xanthorrhoeaceae (Xanthorrhoea)

[Order Dasypogonales]Order Arecales

Family Arecaceae (Palmae) (Trachycarpus, Phoenix)

Order PoalesFamily Bromeliaceae (Dyckia, Fascicularia,

Puya)Family Cyperaceae (Cyperus)Family Restionaceae (Thamnochortus, Elegia)Family Poaceae (Poa, Miscanthus, Arundo,

Phyllostachys, Cortaderia, Stipa, Zea)Order Commelinales

Family Commelinaceae (Tradescantia, Commelina)

Family Pontederiaceae (Pontederia)Family Haemadoraceae (Anigozanthus)

Order ZingiberalesFamily Musaceae (Musa)Family Strelitziaceae (Strelitzia)

2 Both families are included in Amaryllidaceae in APG III3 Both families are included in Xanthorrhoeaceae in APG

III

Classification of a selection of plants found in UK horticulture according to the arrangement in

Mabberley’s Plant-book, Ed. 3 (2008)

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Family Zingiberaceae (Cautleya, Hedychium, Roscoea)

Family Cannaceae (Canna)

EudicotsSuperorder Ceratophyllanae

Order CeratophyllalesFamily Ceratophyllaceae (Ceratophyllum)

Superorder RanunculanaeOrder Ranunculales

Family Eupteleaceae (Euptelea)Family Lardizabalaceae (Akebia, Decaisnea,

Holboellia)Family Menispermaceae (Menispermum)Family Berberidaceae (Berberis, Nandina,

Podophyllum, Epimedium)Family Ranunculaceae (Clematis, Anemone,

Adonis, Delphinium, Aquilegia, Helleborus, Glaucidium)

Family Papaveraceae (Papaver, Corydalis, Romneya, Macleaya, Meconopsis, Dicentra)

Unplaced Order Sabiales4

Family Sabiaceae (Meliosma)

Superorder ProteanaeOrder Proteales

Family Proteaceae (Protea, Banksia, Grevillea, Hakea, Telopea, Embothrium)

Family Platanaceae (Platanus)

Unplaced Order Trochodendrales4

Family Trochodendraceae (Trochodendron, Tetracentron)

Superorder BuxanaeOrder Buxales

Family Buxaceae (Buxus, Sarcococca, Pachysandra)

Core EudicotsSuperorder Myrothamnanae

Order GunneralesFamily Gunneraceae (Gunnera)

Superorder BerberidopsidanaeOrder Berberidopsidales

Family Berberidopsidaceae (Berberidopsis, Aextoxicon)

Unplaced order Dilleniales5

Family Dilleniaceae (Hibbertia)

4 The position of these two orders with respect to the Proteanae and Buxanae is still unresolved and hence they are treated as “unplaced”

5 Order Dilleniales not recognised in APG III; the family is left as “unplaced”

Superorder CaryophyllanaeOrder Caryophyllales

Family Nepenthaceae (Nepenthes)Family Droseraceae (Dionaea, Drosera)Family Tamaricaceae (Tamarix)Family Frankeniaceae (Frankenia)Family Plumbaginaceae (Plumbago,

Ceratostigma, Armeria, Limonium)Family Polygonaceae (Polygonum, Persicaria,

Rheum)Family Caryophyllaceae (Dianthus, Lychnis,

Gypsophila)Family Amaranthaceae (Amaranthus, Beta,

Chenopodium)Family Portulacaceae (Portulaca, Lewisia,

Calandrinia)Family Cactaceae (Opuntia, Cereus)Family Aizoaceae (Carpobrotus, Delosperma,

Ruschia)Family Phytolaccaceae (Phytolacca, Ercilla)Family Nyctaginaceae (Mirabilis)

Superorder SantalanaeOrder Santalales

Family Loranthaceae (Viscum)Order Saxifragales6

Family Cercidophyllaceae (Cercidophyllum)Family Crassulaceae (Crassula, Kalanchoe,

Sedum, Sempervivum, Echeveria)Family Daphniphyllaceae (Daphniphyllum)Family Grossulariaceae (Ribes)Family Haloragaceae (Haloragis)Family Hamamelidaceae (Hamamelis, Parrotia,

Corylopsis, Liquidambar7)Family Iteaceae (Itea)Family Paeoniaceae (Paeonia)Family Saxifragaceae (Saxifraga, Astilbe, Bergenia,

Darmera, Heuchera, Rodgersia, Tiarella)

Superorder RosanaeOrder Vitales

Family Vitaceae (Vitis, Parthenocissus)Order Crossosomatales

Family Staphyleaceae (Staphylaea)Family Stachyuraceae (Stachyurus)

Order Geraniales8

Family Melianthaceae (Melianthus, Greyia)

Family Francoaceae9 (Francoa)Family Geraniaceae (Geranium, Pelargonium,

Erodium)Order Myrtales8

6 Treated as “unplaced” in APG III, i.e. not assigned to a Superorder

7 Recognised in APG III in the separate family Altingiaceae8 APG III has these orders in the Malvids – Eurosids II9 Included in Melianthaceae in APG III

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13Plants in their proper places

Family Lythraceae (Lythrum, Punica, Lagerstroemia, Cuphea, Heimia)

Family Onagraceae (Fuchsia, Clarkia, Oenothera, Gaura)

Family Myrtaceae (Myrtus, Eucalyptus, Callistemon, Luma, Acca, Leptospermum)

Family Melastomataceae (Tibouchina, Osbeckia, Heterocentron)

Fabids – Eurosids IOrder Zygophyllales

Family Zygophyllaceae (Peganum)Order Celastrales

Family Celastraceae (Euonymus, Maytenus, Parnassia)

Order MalpighialesFamily Salicaceae10 (Salix, Azara, Idesia,

Poliothyrsis, Populus)Family Violaceae (Viola, Melicytus)Family Passifloraceae (Passiflora)Family Euphorbiaceae (Euphorbia, Ricinus,

Codiaeum, Acalypha, Croton, Mallotus)Family Hypericaceae (Hypericum)Family Linaceae (Linum)

Order OxalidalesFamily Oxalidaceae (Oxalis, Biophytum)Family Cunoniaceae (Eucryphia, Weinmannia)Family Elaeocarpaceae (Crinodendron, Aristotelia)

Order FabalesFamily Quillajaceae (Quillaja)Family Fabaceae (Acacia, Cercis, Gleditsia,

Caesalpinia, Sophora, Baptisia, Cytisus, Genista, Lupinus, Indigofera, Wisteria, Phaseolus, Robinia, Coronilla, Clianthus, Trifolium, Lathyrus, Pisum)

Family Polygalaceae (Polygala)Order Rosales

Family Rosaceae (Rosa, Potentilla, Geum, Alchemilla, Acaena, Filipendula, Exochorda, Spiraea, Kerria, Dryas, Rubus, Prunus, Chaenomeles, Malus, Sorbus, Cotoneaster, Pyracantha)

Family Elaeagnaceae (Elaeagnus, Hippophae)Family Rhamnaceae (Rhamnus, Ceanothus,

Colletia)Family Ulmaceae (Ulmus, Celtis, Zelkova)Family Cannabaceae (Cannabis, Humulus)Family Moraceae (Morus, Ficus, Broussonetia)Family Urticaceae (Urtica, Boehmeria)

Order CucurbitalesFamily Corynocarpaceae (Corynocarpus)Family Coriariaceae (Coriaria)Family Cucurbitaceae (Cucumis, Cucurbita,

Bryonia, Ecballium, Citrullus)Family Datiscaceae (Datisca)

10 Includes a number of genera formerly assigned to the Flacourtiaceae

Family Begoniaceae (Begonia)Order Fagales

Family Nothofagaceae11 (Nothofagus)Family Fagaceae (Fagus, Quercus, Castanea,

Lithocarpus)Family Myricaceae (Myrica, Morella, Comptonia)Family Betulaceae (Corylus, Betula, Carpinus,

Alnus)Family Casuarinaceae (Allocasuarina)Family Juglandaceae (Juglans, Carya,

Pterocarya)

Malvids – Eurosids II[Order Huerteales][Order Picramniales]Order Brassicales

Family Tropaeolaceae (Tropaeolum)Family Limnanthaceae (Limnanthes)Family Resedaceae (Reseda)Family Capparaceae (Capparis)Family Cleomaceae (Cleome)Family Brassicaceae (Brassica, Erysimum,

Aubrieta, Matthiola, Lunaria, Iberis, Raphanus, Crambe)

Order MalvalesFamily Malvaceae (Tilia, Lavatera,

Fremontodendron, Hoheria, Althaea, Alcea, Hibiscus, Abutilon)

Family Thymelaeaceae (Daphne, Edgeworthia, Wikstroemia)

Family Cistaceae (Cistus, Halimum, Helianthemum)

Order SapindalesFamily Sapindaceae (Acer, Aesculus, Dodonaea,

Koelreuteria)Family Simourabaceae (Ailanthus, Picrasma)Family Anacardiaceae (Rhus, Cotinus, Schinus)Family Rutaceae (Citrus, Choisya, Skimmia,

Phellodendron, Dictamnus, Ruta, Cneorum)

Superorder AsteranaeOrder Cornales

Family Cornaceae (Cornus, Alangium)Family Nyssaceae (Nyssa, Davidia)Family Hydrangeaceae (Hydrangea, Deutzia,

Philadelphus, Carpenteria, Kirengashoma)Family Loasaceae (Loasa, Mentzelia)

Order EricalesFamily Balsaminaceae (Impatiens)Family Polemoniaceae (Phlox, Polemonium,

Cantua, Cobaea, Gilia)Family Theaceae (Camellia, Stewartia)Family Pentaphylacaceae (Cleyera, Eurya)Family Ebenaceae (Diospyros)Family Primulaceae (Primula, Cyclamen,

Dodecatheon, Lysimachia, Myrsine)

11 Previously included in the Fagaceae

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14 Plants in their proper places

Family Styracaceae (Styrax, Halesia, Pterostyrax)

Family Diapensiaceae (Diapensia, Galax, Shortia)

Family Actinidiaceae (Actinidia, Clematoclethra, Saurauia)

Family Sarraceniaceae (Sarracenia)Family Clethraceae (Clethra)Family Ericaceae12 (Erica, Calluna, Cassiope,

Kalmia, Rhododendron, Vaccinium, Pyrola, Empetrum, Cyathodes, Richea)

Lamiids – Euasterids IFamily Boraginaceae13 (Borago, Echium,

Nemophila, Anchusa, Lithodora, Omphalodes, Pulmonaria, Phacelia)

Order GarryalesFamily Eucommiaceae (Eucommia)Family Garryaceae (Aucuba, Garrya)

Order GentianalesFamily Rubiaceae (Coprosma, Bouvardia,

Luculia, Asperula, Phuopsis)Family Gentianaceae (Gentiana, Eustoma,

Exacum, Centaurium)Family Apocynaceae14 (Nerium,

Trachelospermum, Vinca, Asclepias, Hoya, Dregea, Stapelia)

Order SolanalesFamily Solanaceae (Solanum, Lycium,

Cestrum, Nicotiana, Datura, Petunia, Salpiglossis)

Family Convolvulaceae (Convolvulus, Ipomoea)

Order LamialesFamily Oleaceae (Fraxinus, Jasminum, Olea,

Osmanthus, Syringa, Ligustrum)Family Gesneriaceae (Haberlea, Ramonda,

Mitraria, Achimenes, Streptocarpus)Family Calceolariaceae (Calceolaria, Jovellana)Family Scrophulariaceae (Verbascum,

Phygelius, Diascia, Nemesia, Buddleja, Myoporum)

Family Acanthaceae (Acanthus, Justicia, Strobilanthes)

Family Verbenaceae (Aloysia, Verbena, Rhaphithamnus)

Family Bignoniaceae (Catalpa, Eccremocarpus, Campsis, Incarvillea)

Family Lamiaceae15 (Lamium, Clerodendrum, Vitex, Callicarpa, Caryopteris, Phlomis, Salvia, Mentha, Thymus, Plectranthus, Stachys)

12 Including Empetraceae and Epacridaceae13 Family is “unplaced” (unassigned to an order) in both

Mabberley & APG III; also includes Hydrophyllaceae14 Including Asclepiadaceae15 Including some genera formerly in the Verbenaceae

Family Phrymaceae (Mimulus)Family Paulowniaceae (Paulownia)Family Orobanchaceae (Castilleja, Lathraea)Family Plantaginaceae16 (Digitalis,

Antirrhinum, Penstemon, Hebe, Rehmannia, Bacopa)

Campanulids – Euasterids IIDesfontaniaceae17 (Desfontania)Escalloniaceae18 (Escallonia)Order Aquifoliales

Family Helwingiaceae (Helwingia)Family Aquifoliaceae (Ilex)

Order ApialesFamily Griseliniaceae (Griselinia)Family Araliaceae (Aralia, Schefflera,

Pseudopanax, Hedera, Hydrocotyle)Family Apiaceae (Astrantia, Eryngium, Daucus,

Bupleurum, Angelica, Foeniculum)Family Pittosporaceae (Billardieria,

Pittosporum)Order Dipsacales

Family Adoxaceae (Adoxa, Viburnum, Sambucus)

Family Caprifoliaceae19 (Lonicera, Abelia, Diervilla, Linnaea, Knautia, Scabiosa, Valeriana, Centranthus, Morina)

Order AsteralesFamily Rousseaceae (Carpodetus)Family Campanulaceae20 (Campanula,

Platycodon, Adenophora, Codonopsis, Lobelia)

Family Argophyllaceae (Corokia)Family Menyanthaceae (Menyanthes)Family Goodeniaceae (Scaevola)Family Asteraceae (Aster, Echinops,

Eupatorium, Centaurea, Senecio, Dahlia, Helichrysum, Osteospermum, Bellis, Erigeron, Chrysanthemum, Helianthus, Mutisia, Olearia)

16 Including Globulariaceae17 Treated as “unplaced” family by Mabberley, but included

in the Columelliaceae, in the order Bruniales (not recognised by Mabberley) in APG III

18 Treated as “unplaced” family by Mabberley, but placed in the order Escalloniales (not recognised by Mabberley) in APG III

19 Including Dipsaceae, Valerianaceae and Morinaceae20 Including Lobeliaceae

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