Thursday, June 07, 2007

What is a Lily? A mini botany lesson

There is much disagreement even amongst botanists, but there are similar characteristics!

Most lilies once to belonged to the family Liliaceae. However more recently, many genera have been placed in other botanical families such as the mat-rushes (genus Lomandra) and grasstrees (genus Xanthorrhoea), now in the families Dasypogonaceae and Xanthorrhoeaceae. Nevertheless, they all have some basic features that place those plants into this lily area of classification.

Lilies can be found in most parts of the world with thousands of species and hundreds of genera. So as can be imagined, they come in many guises. In Australia (under the old classification) there were around 60 genera and 300 species, giving us somewhere around 7-8% of the world's lily species.

A typical lily flower, this is the prolific Chamaescilla corymbosa, or Blue Stars. It is a small herb growing from a tuber each winter/spring, and occurring extensively in all southern Australian States.

Blue Stars, Chamaescilla corymbosa

So what is a lily? Firstly they are herbs; i.e. they are not woody with a cambium layer like most shrubs and trees. The leaves are parallel-veined and not interconnected with other veins (reticulated). The flowers have petals and sepals (sepals are the parts that cover the flower in bud), but with lilies, orchids, etc, they are usually petal-like in both color and texture, although they may differ in shape and size.

Blue Stars often carpet the ground where they occur, making a particularly colorful display.

The flowers are made up of three petals and three sepals (although they can appear to be the same (then both known as tepals), however at the flower base, the sepals are the ones on the outside, with the petals on the inner portion next to the (3 or more often 6) stamens. The ovary sits on top of the petals, not below them. So if you have a plant with all these features, then you have a lily or a plant once grouped with them.

A Wurmbea species (collectively known as Early Nancies) that some botanists have now placed in the family Colchicaceae, although some still retain it in Liliaceae. It is slightly smaller than the Blue Stars above, and some species commonly flower with them.

Another Wurmbea species, but is usually only seen around ephemeral swamps following bushfires. Most lilies respond very well to fires, usually producing mass flowering in the following growing season.

Wurmbea species

The pretty Fringe Lily (genus Thysanotus), like the Early Nancies above, have by some botanists been placed in the family Anthericaceae, although some still retain them in Liliaceae. Generally a larger plant than those above, with some creeping/climbing and others with a shrubby appearance. However many are spindly and go unnoticed until they appear in flower, then you cannot miss them.

Fringe Lily, Thysanotus species

A closer photo of another Thysanotus species. It is interesting to note that these flowers close at night or on overcast days, only to reopen during sunnier periods. The fringe first folds into the petals, then the petals fold lengthwise and close together. The narrower sepals then partially cover them. Most lilies have this habit of closing at night, although these fringe lilies would rank amongst the most complex and delicate to do so.

A very common lily particularly around granite outcrops, are the Bulbine Lilies (genus Bulbine). These occur throughout Australia where suitable conditions are found, possibly because the water run-off from the granite provides a prolonged moist habitat for them. These too have been removed from the family Liliaceae by some botanists and placed into the family Asphodelaceae.

Bulbine Lily, Bulbine species

Below is one of the Rush-lilies, or in this case the Autumn Lily (genus Tricoryne), Like some of the fringe lilies, they are almost impossible to find when not in flower, being able to blend perfectly into other vegetation. Note the tufted stamens, an added feature to enhance their interest and beauty. These lilies like the fringe lilies have also been placed by some into the family Anthericaceae

Autumn Lily, Tricoryne species

Next the Grass Lilies from the genus Caesia, now relocated by some botanists from the family Liliaceae to Anthericaceae, along with the fringe and rush lilies. As with the others they are virtually impossible to spot without their flowers, which with most species occur in numbers along the stem.

Below is another grass lily, this time Caesia viscida (named in 1990) a rare and little known species previously only collected from the (near Esperance) Cape Le Grand National Park. I discovered three new colonies after a bushfire next door to me. It forms quite a large tussock of about 50 cm diameter, and the approximately 40 cm long leaves are very viscus, i.e. sticky, and usually have sand grains attached near their base. The flowers are hidden, originating from near ground level and are mostly concealed by the spreading leaves. So it was quite exciting to discover the identity of this plant, after having walked past them several times and assumed (not a good idea with plants) that it was a sedge, currently without flowers.

Grass Lily, Caesia viscida

Once placed in Liliaceae, then into Xanthorrhoeaceae and now by some into Dasypogonaceae, the Mat-rushes from the genus Lomandra. These occur in all Australian States, plus in New Caledonia and New Guinea. This is an interesting conundrum as Western Australia is the only State with most of the other genera from Dasypogonaceae. So it seems doubtful that the other States, let alone countries, are going to readily recognise the latest family change. Such is the confused fate/state of some flora with lily connections.

Below are Grasstrees after fire from the genus Xanthorrhoea and the family Xanthorrhoeaceae, yes the same family the mat-rushes above are/were once placed. These however are retained by most taxonomists in Xanthorrhoeaceae. These large plants some to several metres in height are still technically herbs and not trees at all. The trunks are made from the base of the tough long, but relatively slender leaves (the major part being burnt off during bushfires). These are cemented together by the resin produced by the plant, which becomes liquefied during hot bushfires, the centre of the plant is relatively soft and pithy, but is protected by the 3 cm or so thick, cemented, leaf-base trunk. These grasstrees love fire and few are killed even by the hottest bushfire, many will only flower after they have been burnt, as can be seen by all the developing flowering spikes in the photo.

So why you may ask, does this very un-lily like plant get lumped in with them. As can be seen in the photograph, the structure of the flower is very lily-like, there are three small petals, plus three small (similar looking) sepals, six stamens and a superior ovary. These flower spikes can be several metres in length and contain thousands of tiny cream flowers, they are consequently a great food bonanza when in flower and are a great favorite with honeyeating birds and numerous insects.

Grasstree flower-spike, Xanthorrhoea species

There are of course many other common Australian lily species, but space prohibits their inclusion, the above is just an indication of what makes a lily a lily, combined with a taxonomic riddle that has been around for a very long time and shall probably remain so for some time yet.

Not all, but many of the small ephemeral lilies produce a small tuber. These are quite edible and were commonly eaten by the aborigines, they are tasty being like a small crunchy (less starchy) potato. The aborigines also used the resin from grasstrees as an adhesive to make axes, knifes, spears, etc. The grasstree flower spikes were also used for short hand spears. So lilies are not only pretty, but some have very practical uses too.

Many people go to great lengths to find orchids, but lilies can be just as exciting to hunt down as like orchids, you must be in the right place at the right time to find them. They are I think just as attractive to view and photograph, and with over 300 species within Australia and still probably new ones to discover, they would prove to be a worthy extension of interest, if not a passion in the making.


Geoff_D said...

Very interesting, and confusing. Thanks for the enlightenment.

Esperance Blog said...

Thanks geoff, yes the lilies are fought over just as much as the classification for orchids are. Must be the passions of the taxonomists. :)

Gaye from the Hunter said...

Another very interesting "mini botany lesson", Jack, from which I have learned much.

"The flowers are made up of three petals and three sepals (although they can appear to be the same (then both known as tepals)..."

I will check this feature out when next I come across a flower that I suppose might be a lily.

Actually, the dreaded onion weed that pops up in my lawn is most probably a lily, so will be no shortage of a specimen to study.

I haven't seen any of the Early Nancy lilies in this area for many many years. I used to see them when I was a child, and I remember I called them 'snow drops'.

I noted some of the species you have featured, on my trip to WA last year - pretty and dainty flowers.

I am most intrigued as to why flowers close at night. I am supposing it has something to do with self-protection, but whether it be from nocturnal animals that might displace valuable pollen, or from harsh weather conditions, is a bit of a mystery.


Esperance Blog said...

Hi Gaye, I suspect lilies close at night to prolong their productive life. Some, like the fringe lilies are extremely delicate and so easily damaged, also their pollinators are unlikely to be around at night, plus they would need to produce more nectar or scent pheromones, so wasted energy.

Many also close when overcast and raining, which I would imagine would be for similar reasons. Plants are proving to be a lot smarter and sensitive than we have previously thought, You never know, there may come a day when we feel guilty about eating salads. :)