DIVERSE DANDELIONS
K Butler

Recently a new book described the 132 species of dandelion which were known to grow in the British Isles. The great diversity in form of dandelions arises because they are able to produce seed without pollination. Hence there is no crossbreeding and any unusual trait which develops is passed on to the following generations, Hence from a single ancestor species which probably grew in the Himalayas there have emerged some 2000 species, many of which are vigorous and successful.

The modern Caithness dandelions may be grouped into three sections:

Section Vulgaria
The dandelions in your garden are probably of this type. Why not dig one up and examine it? Vulgaria are big plants. The petals of the flower head (ligules strictly) are yellow in the inside, but striped on the back with another colour - in most Vulgaria a shade of grey. The flowers appear in April to June and can flower late in the year sometimes. Where the flower head joins the flower stem is a ring of small triangular leaflets called involucral bracts. Usually they are curved downwards in Vulgaria. Their colour varies from the violet - purple of Taraxacum cypanolepis at Reay to the colourless T. latisectum of Olrig woods. The leaf stalks of dandelions vary from pale green to rich ruby red and are an important diagnostic feature. But the most difficult character to learn and diagnose is the leaf shape. The end lobe can be shaped like an arrowhead, a spade, a triangle or a helmet perhaps. The side lobes sometimes point downwards sometimes upwards and occasionally straight out. The ends can be quite blunt or sharply pointed. These things are used to identify the species. Vulgaria grow just about anywhere except acid peatlands.

Section Obliqua
I doubt if you have one of these in your garden because they grow only on sand dunes around the Scottish coast and a few western English spots. In Caithness one species is known from Dunnet Links. The remarkable feature is the small delicate rosette of leaves only about 3" across the circle. The leaves are dark green and finely divided into many lobes. The involucral bracts are small and do not curve back.

Section Spectabilia
If the leaves are spotted and the leaf stem is red then the dandelion probably belongs in this group. Most of the ones we know about grow on the sand dunes of Dunnet and Reay but the rather distinctive T. Maculigerum has been found in a few rocky hilly situations and is probably quite common. Plants in this section have their ligulus striped with bright carmine or purple and the involucral bracts often stay upright and close to the flower head.

We should hope to find some member of the section Erythrosperma in Caithness some day but nothing has been turned up yet. They are small plants like Obliquae and grow in rocky and sandy situations.

No dandelion hunting had ever been done in Caithness until last spring when I made a collection from many stations. Not surprising either!  The quickest way to become the object of jovial remarks is to lie in the ditch and admire the dandelions. After that comes the pressing. The leaves are very juicy and it is necessary to change all the pressing papers every day for about two weeks until the whole house seems to fill up with damp newspaper. However the results of the hunt were most rewarding. Pride of place went to the discovery of a species new to the British Isles - Taraxacum septentrionale which was previously known from northern Scandinavia.  And then T. orcadense which was previously known from Orkney and Shetland is now recorded from the British mainland all along the roadside from Thurso to Castletown. 

In all 1 9 species were seen and bring the county total up to 22. Now it remains to prepare detailed maps of the distribution of the species in the county and that is going to take many years yet.

Published April 1974