Stoneworts (this is Chara fragilis), are the closest relatives to the land plants amongst the algae. They differ from most other green algae in having a well defined meristem: the 'bud' at the top of a land plant's stem.

Thalloid liverworts look a lot like beached seaweed. They have no cuticle, the waxy coat on plant leaves that stop them drying out. Consequently liverworts often live in damp places, like greenhouses, forest floors and near streams. This is Marchantia polymorpha.

Hornworts, like this Anthoceros punctatus look a bit like liverworts with horns. The horns are the diploid reproductive structures. In mosses, hornworts and liverworts, the plant you see is haploid (only has one set of chromosomes): the diploid stage (two sets like humans and most other plants) is very small.

Sphagnum fallax and related mosses are actually the dominant species of vast tracts of mire and bog, which is ironic considering the way mosses are dismissed as primitive and dull by most people.

The true clubmosses, like this Lycopodium pinifolia look something like a pinecone. Clubmosses are not mosses at all: they are actually more closely related to daisies than they are to mosses, as the cladogram on the left shows. They are fully vascular and reproduce by spores, like ferns.

Spikemosses, like this Selaginella martensii watsonii, show the fractal structure of many 'primitive' plants. The resurrection plant (S. lepidophyllus, withstands drying that would kill a 'higher' plant. Extinct relatives of spikemosses and clubmosses include Zosterophyllum and Sawdonia, which like these plants, lack true leaves.

The squashed trunks of Lepidodendron and Sigillaria are major contributors to coal, formed in coal forests during the Carboniferous period. The last remaining close relative of these giant clubmosses are quillworts, like Isoetes lacustris. It is endangered, rare and biologically important, but not quite as photogenic as a panda.

Whiskferns have had a chequered classificatory history. For many years, the similarity of whiskferns (Psilotum and Tmesepteris) to the first vascular plants (Cooksonia and Rhynia) meant that most botanists thought they were relics of the Devonian. However, molecular evidence points to their being closely related to ferns.

Botrychium lunaria. These adders-tongue fern and its allies have been traditionally classified with the rest of the ferns, but molecular evidence groups them with the whiskferns.

The horsetails (this is Equisetum telmateia) are the tiny remnants of a once hugely important plant group, which included the Carboniferous giant horsetail Calamites. The ferns and other vascular plants differ from the clubmosses in having true leaves, probably formed by webbing across small branches. The first plant with this feature was Trimerophyton.

Marattia is a tropical fern, one of this large group of overlooked plants. Ferns are actually very common, and although often associated with damp places, there are desert species, and the most successful plant species on Earth is arguably bracken.

The ferns are the second most diverse of the three groups of vascular plants. This is Asplenium bulbiferum.

Welwitschia mirabilis is one of the gnetophytes, a group widely thought to be the sister group of the flowering plants; however, morphological and molecular data conflict wildly, and Deep Green has them as the sister group to both flowering and coniferous plants. Welwitschia only ever grows two huge ribbon like leaves, and has cone-like flowers.

Gnetum gnemon is a member of the type genus of this group, the gnetophytes. Welwitschia is a desert shrub, whereas Gnetum is a tropical tree. All gnetophytes have an unusual double-fertilisation that is only otherwise found in angiosperms.

Ephedra sinica is a final member of this group. The drug ephedrine, which is used as a nasal decongestant, is extracted from this grass-like herb.

The waterlilies (Nymphaea), are an early offshoot of the flowering plants. There is some debate over whether the earliest flowering plants were herbs or trees. I think the current consensus is shrubs (Amborella trichopoda has the dubious honour of being denigrated as the most 'primitive' living angiosperm, a position previously bestowed upon Magnolia, Ceratophyllum and others.

This is Liriodendron tulipifera, a close relative of the magnolia. The evolution of the angiosperms has always been contentious: the Gondwanan tongue-ferns (Glossopteris), Pentoxylon, Caytonia and Cycadeoidea are currently the best guess as to the closest extinct relatives of the angiosperms.

The aroids, including Arisaema ringens are members of the huge and important monocot plants, which bear seeds with only one seed-leaf. Aroids exploit insects, which is a common strategy amongst the flowering plants.

It's difficult to do justice to the diversity of flowering plants, but you all know what bananas, lilies, irises (Iris siberica, left), and similar look like, so I'm trying to give more space to the things you've never heard of instead!

The palms (e.g. Johannesteijsmannia magnifica), are an exception to the rule that monocots are herbs not trees. It is thought that monocots evolved from water plants, as their lack of true wood and true leaves attest.

Zea mays, an economically important grass (maize), will represent the huge commelinid clade, which includes grasses, sedges, rushes, bromeliads (pineapples), and a vast number of other important monocot plants.

The ranunculids are a group of plants that are thought to branch deeply from the major lineages of dicots. This is Papaver orientale, the oriental poppy; other ranuculids include the buttercups.

Cleistocactus brokei is a caryophyllid, a major group that includes most of the carnivorous plants.

Rosa rugosa, the rose, is a member of the eponymous rosid clade, which includes many flowering plants, such as roses, cabbages and oaks. The rosids and asterids (see below) are the main groups of dicot plants, which are those with two seed leaves.

The asterids comprise mints, daisies, nightshades, cornflowers (Centaurea nigra) and so on. Daisy 'flowers' are actually hundreds of tiny flowers squished into a flat cup. Flowering plants may not have been the first group to exploit animals for reproduction, but they are one of the most successful.

The cone of a cycad, Cycas thouarsii. The cycads and other gymnosperms seem to be the sister group of an extinct lineage of 'progymnospersm', which includes Archaeopteris (one of the first trees) and other 'seed-ferns', which are characterised by fern-like foliage, but gymnosperm-like reproductive organs.

Ginkgos are the last remaining species of maidenhair tree, a once common group. Ginkgo biloba is now only found in captivity.

Pinus and its relatives are conifers, characterised by their cones and needle-like leaves. Many of these species are found in the northern (Laurasian) hemisphere, named after the northern continent of the Carboniferous period. The flora of Laurasia is quite distinct from…

…the flora of the southern (Gondwanan) hemisphere, including the monkey puzzle and other species of Araucaria araucaroides. The Gondwanan fauna is also quite distinct: marsupials are only found in South America and Australasia.

The yews (Taxus baccata), are often found in churchyards in England. However, the trees are actually older than the churches in many cases, and are probably associated with pre-Christian sites of pagan worship.