Thistle like plants for the garden – Botanically Inclined

Centaurs – Greek mythological figures with a man’s upper body and a horse’s lower half. Supposedly, they were using the (Centaurea) flowers for healing (Centaurea scabiosa as header image)

Continuing the year of the thistle with Centaurea spp., which are not true thistles of course, but included in the big family. Actually, there are a few species with a true thistle-like look! Again, leaving the weedy ones apart, there are many worth cultivating besides the common C. nigra, C. montana and variants. ALL Centaurea species are most valuable to bees and attract countless species of butterfly, moths and other insects AND they are easy to grow from seeds!

In many cases, the involucral bracts (phyllaries) are very ornamental, a detail sometimes overlooked but which serves in species identification. Below, a few Centaurea sp. from the Carpathian Mts. (some endemic, some with a wider distribution). Bright pictures for a cloudy day!

Centaurea kotschyana

Centaurea kotschyana

Centaurea pseudophrygia

Centaurea pseudophrygia

Centaurea triumfettii ssp. stricta

Centaurea triumfettii ssp. stricta

And how about the yellow-flowered Centaurea? Here is the rare yellow form of C. kotschyana:

Centaurea kotschyana yellow form

Two species in the Newly arrived Seeds category: C. salonitana and C. orientalis also have yellow flowers, but there are many other species. And I think the dwarf Centaurea drabifolia (endemic of Turkey!), seen here in the Rock garden at the Montreal Botanic Garden, can very well conclude this short post on Centaurea.

Centaurea drabifolia

I hope I convinced at least a few to pay more attention to Centaureas. I look forward to combine in our garden, the yellow Centaurea salonitana together with Salvia pratensis in a flower bed, while the smaller Centaurea triumfettii ssp. stricta will be attracting butterflies in the rockery area ;)

You can also see the Carpathian Mts. endemic Centaurea pinnatifida here.

The beginning of the New Year has been busy with new seeds arrivals. Having a new garden space means also having new plants interests. Therefore, I declare 2016 as The Year of the Thistle!

According to wiki, “Thistle is the common name of a group of flowering plants characterized by leaves with sharp prickles on the margins, mostly in the family Asteraceae”. But besides the ‘true thistles’: Cirsium, Carduus and Onopordum, other genera that don’t have spiny leaves are also included and called thistles: Jurinea, Centaurea, Carthamus, Carlina, Rhaponticum, Echinops, Silybum, Berkheya and so on.

Few plants are more beneficial to bees, bumblebees and butterflies than thistles; also, many birds are consuming their seeds. Quite a few are cultivated as economical/medicinal plants. The oldest cultivated ‘thistle’ in the world was Carthamus tinctorius (safflower).

Unfortunately the name ‘thistle’ brings to mind mostly awful weeds. However, there are many species that are non-invasive and highly ornamental; some are even endangered in their wild habitat! To name only 2 North American Cirsium species that are not weedy and have become endangered: the endemic Cirsium hillii (C. pumilum var. hillii) – seen in the image, and C. pitcheri. Cultivated in the gardens but not too often is Cirsium canum (Queen Anne’s Thistle).

Cirsium hillii growing under a Jack pine (P. banksiana)

A most interesting genus is Jurinea. These are species familiar mostly to plant collectors; the genus includes alpine/sub-alpine species growing in mountain meadows, a few rare and/or endemics. In the image is shown Jurinea mollis growing in a sub-alpine meadow in the Carpathian Mts.

Jurinea mollis in the Carpathian Mts.

Other great species practically unknown in cultivation are Jurinea iljinii – with a restricted distribution range in the western part of the Greater Caucasus, and Jurinea sordida endemic in Crimea. They all have in common, non-spiny, finely lobed leaves and purple (in various shades) flower heads, which take on a beautiful silky appearance when the seeds are ripened.

Jurinea mollis seedhead

There are also nice, low-growing Jurinea ssp. for the rock garden (if you can find seeds) like J. depressa and J. macrocephala, to name just a couple. From the low-growing thistles category, I will have to contend for now with the alpine thistle: Carlina acaulis. You can read more about it here.