Taxonomical notes on the grouping of plants on the Natural History Site of Iceland

A few notes on the lists

Any author describing plant species has to face the problem of addressing different audiences. Basically there are two opposite approaches: the scientific and the popular. The scientific approach in listings of plant species is very straight forward: it uses the general order of plant systematics. For the specialist this is basic stuff. However, when authors want to address the general public they are tempted to use a different order of listing. To be more concrete: they use flower colors as a first major distinguishing character. One does not have to have knowledge about difficult, often minuscule, plant-traits to tell yellow flowers from red flowers. Thus one can find many field-guide books based on this principle. The standard Icelandic field guide on Icelandic plants: "Flowering Plants and Ferns of Iceland" by Hörður Kristinsson is a typical example. For the trained botanists it means however, that closely related species are dealt in very different groups (pages of a field guide book).

I have chosen to select a presentation strategy that is partly scientific and partly populous. In order to do this I have used the rather old-fashioned groups of the Choripetalae and Sympetalae. Before explaining the meaning of these expressions it is probably a wise to list the general groups of plant taxonomy:

• Algae and sea weeds: not discussed here.
• Moulds and mushrooms: not discussed here.
• Lichens: Symbiontic life forms of algae and moulds, not discussed here.
• Mosses: not discussed here - not with standing the huge importance of mosses for the vegetation of Iceland !
• Primitive and True ferns: The top/first list - although not the opening list.
• "Gymnospermae": Primitive seed-forming plants. The name is an old one that still prevails as a concept, although specialists believe it does not represent a group of rather closely related species. Most groups have no relevance to Iceland except the Pinaceae family (the pine tree family)
• "Angiospermae": True flowering plants. I have divided them into the 3 main groups: the Choripetalae, Sympetalae and Monocotolydon groups.

So what do Choripetalae, Sympetalae and Monocotolydon mean? First monocotyledons. Basically the monocotyledons have one leaf during the early seed germinating phase where the dicotyledons have two. There are many other characteristic differences: the monocotyledons have flowers based on 3 (e.g. three petals 6 stamens), where the dicotyledons have flowers with basic structures of anything from 2, 4 or 5 to many. Also moncotolydons have leaves with parallel structured veins unlike nearly all other plants which have net-structured veins or branching vein structures. Think of grass leaves. Among the monocotyledons are major groups as grasses, sedges, orchids and lilies & rushes. Recently grasses and sedges are considered a natural group by itself differing as much to the (other) monocotelydons as the dicoteledons.

All others are dicotyledons. Because this is such a large group I used the old but still valid sub-classification Choripetalae and Sympetalae.

• Choripetalae are plants having flowers with their petals (or comparable flower leaves) not joined. Except for the Juniper (and other introduced pine family members) all larger woody species (willows, birches) on Iceland belong to this group. But also many others, like Rose family, Buttercup family, Primrose family, Pink family, Saxifrage family and many others.
• Sympetalae have petals fused at the base or even much upward. Example: Gentian family, Mint family, Bellflower family, Figwort family, Heather family, Daisy family, etc.

A full list of orders and families can be viewed on anwsers.com.

Happy surfing through the site / Dick Vuijk

Be aware of Vuijk's first law on biology: "Where in physics one observation conflicts the theory this theory is falisfied or necessetates a major adaption of the theory, one can expect about as many conflicting observations as affirmative observations for biological theories".