I will attempt to answer the question posed in the title of this piece in a little while. Meanwhile lets consider for a moment what is a thistle. Strictly there is no single species or even one genus that contains all those wild plants found in the UK whose name includes the word thistle. According to my trusty reference books of wild flowers there are 15 UK species called thistle. The common feature is their spikey stems and leaves, evolved to deter grazing herbivores. All bar one seem to have pink/blue/purple flowers. The species vary in their habitat type, some are common and found almost every where in the British Isles others are less common and occur only in more specific habitats and soil types.
There are thistle like plants (in that they are very spikey with blue flowers and resistant to herbivores) for example Eryngyium maritimum the Sea-holly. There are 250 species of Eryngyium worldwide and in addition horticultural cultivars, such as Eryngyium giganteum . That partly answers the question posed earlier. That is gardeners love thistles and thistle like plants from a number of genera. Gardening presenter Monty Don wrote an interesting piece for The Mail online in 2012 on this very matter. For his garden Monty favoured the giant cotton thistle and The Globe Thistle Echinops ritro. We grow The Globe Thistle in our garden and once the flowers open they are irresistible to bees. It always pleases me to see bumble bees and honey bees together on the same flower, often in numbers.There are ornamentals as mentioned already and of course the Globe Artichoke is a thistle. Then there are those who love the thistle as an emblem, for example The Scots. I will leave it there in answer to the question Who loves a thistle?
Moving on to where that love turns to scepticism or hate of thistles. As I mentioned, there are 15 species of wild flower in UK called thistles. Their spikiness makes them unpopular with walkers and gardeners. They are difficult to handle once the plant reaches maturity. Catch them very small and gloves and a fork is all you need to get them to the compost heap. Once mature their flowers attract many insects as they are good sources of nectar. Insects with long tongues can cope with the relatively deep flowers. The various species of Fritillary butterflies are particularly dependent upon thistle flowers for their nectar. Thistles are prolific seeders and so spread quite well. A big plus point for the seeds is that Goldfinches like them. Regarding spreading and being a nuisance, two species of thistle are included in The Weeds Act 1959 and described as injurious weeds. The two in question are The Creeping Thistle Cirsium arvense, and The Spear Thistle Cirsium vulgare. Both are common across the whole of the UK. They are a nuisance in grazing land as they are not eaten by the grazer and crowd out more nutritious plants in their immediate vicinity. Ironically, the latter is probably the species represented in the Scots National emblem.
When I first moved to The Park there were some patches of thistles close to the newly fenced property boundaries so efforts have been made to mow them down each year in the growing season. There are no troublesome patches now.
So this brings me nicely to my recurring theme in these blog pieces. How much mowing and tidying is too much? You may be thinking that thistles can safely be shown no mercy unless they are garden cultivars or artichokes. Wrong, not all thistles in UK are common or widespread. Some only thrive in specific conditions and therefore need some thought and even care. On The Park we have to date managed some grassy areas as meadows. Well meadow-ish. Grass is allowed to grow throughout summer with some mowing in spring and autumn. This allows a range of wildflowers to grow, flower and seed. This undoubtedly benefits wildlife and warms the heart of anyone who derives pleasure from seeing and identifying the wild flora. This management regime for the grass areas in question was with hindsight a good choice. The grassland is on chalk. Chalky grassland supports a wide range of wild plants. One of the thistles with some rarity and limited range occurs in this grass. The Park has various claims to wildlife fame and this thistle, The Woolly Thistle Cirsium eriophorum is one of them. The Park is right on the edge of The Woolly Thistle's geographical range and I have personally seen up to 20 plants dotted around on one of our meadow areas. They look impressive when in flower. It is interesting that they seem to be growing in a narrow swathe across the area which suggests to me that wind dispersal of the seed is determining where they occur.
I have no trouble loving this particular thistle because it looks good and attracts beautiful insects but I also feel some responsibility for ensuring that it is not demonised and eradicated from this extremity of its range in the chalky grassland on The Park.