Amazing daisies

Sunday, 06 October 2019

Osteospermum cultivars in the garden of Alice Collins, Sydney

Springtime in Sydney sees a great flowering of many members of the daisy family - called Asteraceae - with such favourites as shrubby Marguerite daisies and Osteospermum; clumping perennial Gerbera and the ox-eye daisy (Leucanthemum vulgare); groundcover forms including Arctotis, Gazania, Brachycome and Erigeron; and annuals such as Bellis perennis and cineraria. However, daisy blooms are not limited to spring! Already the new leaves of herbaceous perennial Dahlia, Echinacea, Rudbeckia and Shasta daisies are appearing, and annual Zinnia, Cosmos and marigold seeds and seedlings are available in nurseries, promising flowers in late spring and summer.

Tagetes lemmonii

Autumn will see the inflorescences of the many perennial Aster species, florists' chrysanthemums, tree Dahlia and tree daisy, along with shrubby mountain marigold (Tagetes lemmonii) and Euryops chrysanthemoides, which both begin their very long blooming period at that time. Annual pot marigolds (Calendula) begin flowering in winter and will continue for months in Sydney gardens. So daisy flowers can decorate our gardens all year round!

Flowers of Eupatorium megalophyllum

Asteraceae is one of the largest of all the plant families, with 1,911 genera and 32,913 accepted species. What we think of as one daisy flower is actually comprised of large number of small flowers, called florets. Ray florets form outer part of the flower and they look like typical petals. Small, tubular disk florets are located at the centre of the flower. However, there are other members of the family that one would be hard-pressed at first glance to identify as belonging to it, as their flowers don't have this classic shape. The overall form of the apparent 'bloom' is comprised of many tiny 'daisies' clustered together. The mist flower (Eupatorium megalophyllum), for example, in bloom now, has puffballs of fluffy lilac flowers: on very close inspection it can be seen that these are comprised of myriad small 'daisy' flowers with threadlike ray florets around a central disc. Annual and perennial forms of Ageratum have the same floral structure, as does Ageratina altissima 'Chocolate'. This is an interesting herbaceous perennial that forms a clump of nettle-like leaves that are beautifully flushed with purplish-brown when they emerge in early spring, and bears clusters of small fluffy white flowers on tall stems in summer, rather like Ageratum. Yarrow (Achillea species) have flat, plate-like heads made up of tiny flowers; sadly I have never had much luck with this Asteraceae plant in my Sydney garden, though I have heard it can become almost invasive if its happily sited!

Helichrysum petiolare

Other Asteraceae plants have very decorative leaves and clustered, quite insignificant flowers, which are often cut off as they detract from the foliage - and again they don't seem to bear any resemblance to other 'daisy' plants! One of my favourites of these is Helichrysum petiolare, a shrubby perennial plant from South Africa, which sends out long stems covered in heart-shaped leaves that look like they have been cut from silvery-grey felt. It forms a mound around 60cm high and up to 1.5m wide. It can be used to cascade over walls or intermingle with other plants; or it can be pruned into a dense rounded thicket. It grows well in both sun and shade and copes well with dry conditions. It has domed of heads of tiny creamy-yellow daisy flowers in late spring, but these are not particularly interesting; they tend not to appear when the plant is grown in shady spots or if the plant is trimmed frequently! There is a lovely cultivar called 'Limelight' that has pale lime-green foliage, which will also grow in sun or shade, and a silver-cream variegated form, 'Variegatum', as well as a cute miniature-leaf form that I recently acquired in a 'plant swap'.

Artemisia Powis Castle (left) with Plectranthus argentatus

Another lovely silver-leaved plant in the Asteraceae family is Artemisia 'Powis Castle', thought to be a cross between Artemisia absinthium and Artemisia arborescens. It has highly dissected, silky, aromatic leaves. I tip-prune regularly to encourage a denser form. It grows best in a sunny, well-drained spot. It has panicles of tiny yellow-tinged flowers in summer, but I remove these, as to me, they detract from the plant. Other silvery-leaved family members are the various species and cultivars of the genus Senecio, with their attractive, highly dissected foliage. The flowerheads are clusters of daisy-like flowers (usually without the ray florets) and are generally not regarded as a positive feature and are removed! I have a few species of these but am quite ignorant of their names! They like a sunny, well-drained position and should be trimmed back regularly to promote a dense form. Like most of these foliage plants, Senecio need to be replaced by a cutting every few years, as they become woody and unproductive with age.

Gynura crepinoides

Another intriguing member of the daisy family with unusual foliage is the genus Gynura, which I have only become familiar with in recent years. The first species I was given, sometimes referred to as Okinawa spinach, I know as Gynura crepinoides, though I suspect this name is not correct. Anyhow, it is a sprawling groundcover with elongated, deep green leaves with purple undersides, which are very pleasing. It can cover quite a wide area and seems best in part-shade. It has a strange orange flower like an emaciated dandelion (which, of course, is also a member of the Asteraceae family), not at all pretty and also rather smelly! A related plant that I was recently given is the truly gorgeous Gynura aurantica, which has broad, velvety green leaves with a purple sheen created by tiny purple hairs - and similar weird flowers! I am planning to place my specimen nearby Strobilanthes dyeriana, which also has an alluring purple sheen to its leaves and grows well in shade. I don't know much about the plant yet but am looking forward to trying it!