It is the time of year when one plant family really shows its full floral power. The Asteraceae, or the Compositae as it was formerly known, is a hugely diverse plant group. This is a family that contains approximately 1620 genera and 23, 600 species ranging worldwide and includes herbs, shrubs, trees and climbers. It also contains not only some of our very well known garden ornamentals (as well as weeds) but also some very important plants for food production. Sunflower is grown for its oil, lettuce and chicory for salad as well its use as a coffee substitute.
The effectiveness of this family comes into play at the end of summer and into autumn where it can provide that final flush of flowers before the temperatures drop with the descent into winter. The flower heads themselves are highly distinctive. The name Asteraceae comes from the ancient Greek word ‘aster’ which means star and refers to the star-like form of the inflorescence. The flower heads are composed of very small flowers called florets surrounded by bracts. A bract is a leaf with a flower in its axil. These calyx-like series of bracts are in one or more rows and the structure itself is known as the involucre. The disc florets are in the centre and the ray florets extend out like petals from the middle. Identifying them can sometimes be tricky as some species only have disc or ray florets. For example, the globe thistle Echinops is composed of only disc flowers. Often the calyx (the collective word for the sepals) may consist of a parachute-like pappus with a ring of hairs to aid in seed dispersal (think of dandelion clocks). The family can be confused easily with the Teasel (Dipsacaceae) and Valerian (Valerianaceae) families, as well as the Sheep’s bit Scabious and Rampions in the Bellflower family (Campanulaceae). Sometimes it is best to consult a key to properly identify a species or just ask someone who knows his or her Asteraceae.
Here are a few favourites spied in the wild and in gardens that have particularly caught my attention:
This is a common plant that grows alongside road verges, grasslands and banks. It caught my eye recently whilst I was walking along the shingle stretch of coast at Slapton Ley in South Devon where it was growing in shingle. The flower colour was a dazzling azure blue in the evening sun. This is definitely one I am sowing in spring for my gravel garden where it will hopefully self-sow each year and will only need thinning to keep it in check.
Leontopodium souliei ‘Compactum’
This is a carpet forming species that I saw growing at the Gothenburg Botanical Gardens. The felt like silvery leaves and its funny fuzzy bracts that are described as being like lion’s paws are quite interesting. The well-known Edelweiss (Leontopodium alpinum) is part of this genus. It was thriving in the dry gravel perennial beds in Gothenburg so it would probably be happy in my gravel garden. Certainly this is one I will try if I can get hold of it.
Tagetes linnaeus ‘Burning Embers’
This species has vivid maroon flowers with a bright edging of orange on the petals. It is half-hardy and can be easily germinated from seed in the spring. This year I grew Tagetes ‘Cinnabar’ in pots but I think I prefer the brighter wider banding of orange on the petals of ‘Burning Embers’. This is one I will experiment with next year in pots.
Calendula officinalis ‘Triangle Flashback’
I love to grow calendulas in pots for their bright displays but also because they are have edible flowers, which are an unusual and colourful addition to food dishes. ‘Triangle Flashback’ has apricot pink flowers with darker undersides; they are very similar to Calendula ‘Bronze Beauty’. This would go well with Tagetes ‘Burning Embers’.
Bidens ‘Pirate’s Pearl’
This is a variety that I am going to trial in pots for next year. Bidens is normally yellow in form but this one is pearly white. It is sterile so produces abundant small white flowers over the whole summer.
The pale coneflower is more subtle than E. pupurea with finely drooping petals that give beautiful seed heads. My own plants have been slow to get going despite an autumn sowing last year, so will not be ready to plant in the garden until next May. One of the benefits of E. pallida is that it is longer lived than E. purpurea.
Echinacea purpurea ‘Alba’
A pale green white form that is stunning in evening sun where I noticed it growing in a garden in southern Sweden in August. This is one I am going to trial in my gravel garden.
I noticed this growing wild on a shingle ridge at Tor Cross in South Devon. It is important for foraging gold finches and insects particularly Lepidoptera. Although a common wild flower, it has attractive shiny-scaled buds and long lasting flowers, which are loved by pollinators. It looked particularly striking growing in the shingle.
Artemisia ludoviciana ‘Valerie Finnis’
Yet another perennial that drew my attention at Gothenburg Botanic gardens and certainly one I will trial in my gravel beds as it is drought tolerant. It has aromatic lance shaped leaves that form an upright mound. The flowers are insignificant but it is grown for the foliage, as the new shoots are a startling white.
This flowers non-stop from July into November. The plants are relatively short lived but will self sow about the garden. The clouds of small starry flowers look great against tall grasses like Miscanthus and Calamagrostis species as well as mid sized varieties like ‘Red Thunder' of Sanguisorba officinalis. The plants can flop so sometimes it will need staking.
Cirsium atropurpureum ‘Mt Etna’
A beautiful pale pink plume thistle that is always engulfed with pollinators. I observed the bees in a feeding frenzy on the flowers. This is subtler than the redder species like Cirsium rivulare ‘Atropurpureum’ but exquisite when viewed close up.