THE WORLD OF THE DAISY
(Adapted from a talk by Alan Gray.)

ASTERACEAE or COMPOSITAE

The word “daisy” is thought to be a corruption of what was perhaps an earlier descriptive name for some members of the Composite family - “The day’s eye” and is  the largest family of flowering plants in the world; some authorities suggest there are well over 20,000 species. The often flamboyant flower of the daisy is not what it first seems, each daisy “flower” is actually a bunch or dense arrangement of many much smaller flowers (or florets) arranged in a single head (or capitulum) which again may be massed collectively into larger composite heads, as in  Olearia argophylla (Native musk), thus the term COMPOSITAE.

The florets in many species may differ within the same head but basically, there are two major types of floret which may comprise a capitulum.  The first is a little tubular flower which bears what appears to be a long single strap-like petal known as a ligule - these florets may make up the entire capitulum as, for example, a dandelion Taraxacum spp. or some forms of the popular ornamental Dahlia.  The second is the tubular floret, which has five petals combined into a tube with the five petal tips free.

Some species bear capitula consisting entirely of tubular florets as, for example, the Ageratum or the Australian native Bedfordia, but where the two are combined in the one head, then probably the most “daisy-like flower” is the result, such as Bellis, Aster, Helianthus (Sunflower), Celmisia (Native snow daisies). In the combined capitulum, the ligulate (strap) florets are always borne on the perimeter of the head with the tubular florets massed in the centre.

Many of the so-called everlasting daisies would appear to belong to either of the first or third type of capitulum.  However, the “everlastings” belong with the second group - those with all florets tubular. Many of the everlasting daisies in Tasmania are no longer included in the genus Helichrysum but the one pictured below, Helichrysum milliganii (Milligan’s everlasting) has not been changed. This lovely tufted plant with its flower heads surrounded by shining white, papery bracts is found on exposed mountain tops and ridges only in Tasmania.

 
Helichrysum milliganii The showy and often colourful ligule “look-alikes” are actually tiers of overlapping bracts (called phyllaries) surrounding the head and which are commonly papery or chaffy in substance.  Thus because these bracts hardly wither or shrivel, they may stay fresh and looking alive for a very long time after the flower is picked.  Hence “everlasting” daisies!  (Helichrysum milliganii - a Tasmania everlasting.) (Image by A. Gray)

The ASTERACEAE is considered to be an advanced and specialised family.  It presents a large number of flowers closely arranged together to effect an efficient pollination of as many individuals as possible, perhaps by only one short visit by a single insect. The method of pollination ensures that out crossing is mostly the case but if this does not occur the floret will eventually self-fertilize. The sepals (calyx), typical of a vast number of flowers of other families, is much modified in the daisy floret and is usually formed into a system of spreading “feathery” strands resembling a parachute or parasol.  This is called the pappus and with the little seed suspended below, this system allows for the most efficient means of distribution - by wind. However a few daisies have no pappus at all and may be dislodged by other physical means; instead of “parachutes” some possess spines or hooks which are caught in the fur or feet of passing animals and are thus dispersed. As strange as it may seem for such a large family, there are very few economically important plants.  Apart from the number of ornamentals e.g. Aster, Gerbera, Chrysanthemum etc. perhaps the most useful plants include lettuce, sunflower, pyrethrum, chicory (coffee additive) and globe artichokes.  A great many of the daisies are “important” weeds of cultivation and/or waste places. The island state of Tasmania is well endowed with a large number of naturally occurring daisies ( and many not-so-welcome introductions!)

 
Olearia argophylla The largest of the Tasmanian daisies would certainly be the so called Native Musk (Olearia argophylla) which is a small tree, between 5m to about 15m, and a very common component of wet forest communities especially along river banks.  Each capitulum is comprised of about 5-12 florets, a few of the outer ones ligulate. However these small heads are massed into large, showy panicles which may all but hide the foliage. (Image by A. Gray) 
 
 

 

Abrotanella forsterioides At the other end of the scale are the midgets of the Tasmanian daisies.  The three shown here are known locally as “cushion plants” because of their tightly compact, mound-like habit.  Abrotanella forsterioides looks more like a bright green moss plant than a prostrate, compact flowering plant.  In this picture it is seen in competition with an alpine sedge Carpha alpina.  The insect at centre gives a useful comparison of proportion.  The capitulum of Abrotanella has only 3-4 florets, only one of which is capable of producing a seed.  It may grow and coalesce together with other Tasmanian cushion plants, and when not in flower, it is difficult to distinguish between the different species. (Image by A. Gray)
Pterygopappus lawrencei Another cushion plant, Pterygopappus lawrencei , is a soft, greyish mosaic, looking like a collection of dozens of tiny cabbages closely packed together.  The tiny capitula seen in this picture have up to 10 (12) florets each. As with other cushion plants, many other plants often “use” them as seed beds; at the lower right hand corner can be seen a couple of seedlings of “Scoparia heath” Richea scoparia. 
 (Image by A. Gray)
Ewartia meredithae Ewartia meredithae does not coalesce and become as tightly compact as some other cushion plants.  It does, however, form small, loose mounds with silvery to rusty leaves and masses of tiny florets in small heads each surrounded by a row of white tipped bracts (phyllaries) c.f. everlasting daisies.
(Image by A. Gray)
Ozothamnus scutellifolius The little shrub pictured here was classified as a Helichrysum but lately has been returned to the genus Ozothamnus.  Ozothamnus scutellifolius, “shield everlasting”, isfound in dry, rocky places, only in Tasmania. The tiny florets are in little heads of about 15-20 which in turn are clustered into larger flower heads of about 3-7 together. It appears to be leafless and covered instead with little green “bumps” or “pimples”. These are indeed the leaves, held closely to the stem on minute stalks, just like a warrior of old time would hold his shield close to his body, hence the specific name scutellifolius - “shield-leaf”! (Photo courtesy Launceston Field Naturalists Club) 
Celmisia saxifraga This lovely Tasmanian is known as “Snow daisy” - Celmisia saxifraga.  A “typical” daisy, and although appearing quite delicate occurs on exposed moors and wet places high on many Tasmanian mountains. (Image by A. Gray) 
Bedfordia linearis The last picture shows another shrubby little Tasmanian, Bedfordia linearis, a plant thought to be closely related to the Senecio genus “groundsels”.  Three species of Bedfordia occur in Tasmania and SE Australian mainland. The bright yellow flower heads consist of tubular florets only, surrounded by a ‘cup’ of bright green phyllaries. The wood of Bedfordia when bruised emits a delightful honey-sweet fragrance. (Image by A. Gray)

Top
Index
Home