Microseris, a tuberous, herbaceous daisy shared among California, Chile, southern Australia, and New Zealand

(writing in progress) 
 
 There are perhaps 40 spp. of Microseris (https://www.inaturalist.org/observations?place_id=any&taxon_id=54047&view=species) in North America, mainly in California, most of which seem to be annuals.

There are also at least two species in South America, namely M. pygmaea in Chile and another in high-altitude Peru https://www.jstor.org/stable/25064004?seq=1#page_scan_tab_contents.

And there are three spp. in southern Australia, one of which also occurs in New Zealand.

Most species seem to have larger, more robust leaves than those of Australian M. lanceolata, growing to 0.5m or even 1 m high in contrast to the mere 10cm which seems usual for the Australian and New Zealand spp.

I have not found any reference to tubers in any of the North American or Chilean spp., whether annual or perennial, and whether the rosette and the leaves are large or small. There are records of the roots of a few spp. being eaten (please see screenshots below) but no indication of anything resembling the pattern seen in aboriginal foraging in e.g. Victoria in Australia.

I have yet to see the term ‘geophyte’ used to describe any species of Microseris.
 
I infer the following:
 
Microseris has its biogeographical centre in California, but has been able to reach Chile and Australasia – despite being absent from Eurasia or Africa.

This genus is everywhere mainly associated with grassland (including high-altitude meadows). However, it does sometimes penetrate wooded vegetation.

The growth-form and phenology resemble that of dandelion (Taraxacum), rather than those of geophytes. The Australasian spp. are odd in being tuberous. However, even in the case of the Australasian spp., I have no evidence that they qualify as geophytes in the sense of dying back each year above ground.
 
Microseris is distinctively Australian, as an aboriginal food-plant, but this is only in a qualified way.

It seems to be only in Australia that Microseris was a staple food of aboriginal people, and this is mainly because the Australian M. lanceolata is odd in its genus in having root-tubers, while growing in vegetation which (relative to e.g. the natural vegetation of California) contains few edible plants.
 
Overall:

Microseris has surprised me in at least two ways.

Firstly, it surprises me that this plant, although tuberous and abundant enough to provide a local staple for Australian aboriginals, seems nowhere to be geophytic. I find it odd for such a small plant to be so tuberous without being geophytic.

Secondly, it surprises me that this plant has such an odd biogeographical pattern: centred in California, with outliers in Chile and also Australia and New Zealand. 
 
https://books.google.com.au/books?id=SUEqUylPDJEC&pg=PA526&lpg=PA526&dq=microseris+in+diets+of+native+americans&source=bl&ots=1YQs4bPUNn&sig=nXX3d6qywdcwisiXs8uTkrjhWTE&hl=en&sa=X&ved=0ahUKEwje0Paz08TRAhWCmZQKHXOyDHEQ6AEIQjAG#v=onepage&q=microseris%20in%20diets%20of%20native%20americans&f=false

https://books.google.com.au/books?id=SRBHfbfi5_cC&pg=PA63&lpg=PA63&dq=microseris+in+diets+of+native+americans&source=bl&ots=3C5XZUF5Hr&sig=gILPKBfJFcF9fMLzfD8jUq8DPqc&hl=en&sa=X&ved=0ahUKEwje0Paz08TRAhWCmZQKHXOyDHEQ6AEIPTAF#v=onepage&q=microseris%20in%20diets%20of%20native%20americans&f=false
 
Realising how important Microseris lanceolata was as an aboriginal food raised several queries along the lines of ecology and biogeography.
 
When I came to Australia from South Africa in 1977, one of the most striking biogeographical differences I found was the relative paucity of daisies (Asteraceae) in Australia.

Daisies dominate various vegetation types in South Africa, but have a low profile in Australia, despite the general association of Asteraceae with island floras (think of the Galapagos).

In various ways, the biota of Australia is island-like. However, the indigenous daisies, in general, show the opposite pattern, at an ecological level.

This is particularly significant, because it is not just southern Africa that has a rich flora of daisies, and various vegetation types dominated by daisies. The Americas, including South America at similar latitudes to Australia, are as rich in daisies as South Africa is. Both the Karoo and Patagonia are to a large extent characterised by Asteraceae.

By contrast, Australian vegetation has only a token of this pattern in the form of Olearia, which is essentially an insular element restricted to Australasia.
 
What all of this means:
The many lineages of perennial daisies, which have come to dominate vegetation types in the Karoo, Patagonia, and elsewhere on other continents, have a negligible representation in Australia. Here, daisies are essentially restricted to annuals/ephemerals (in semi-arid areas), and a few insular genera that have noteworthy diversity in growth-forms (as is typical of island elements), but limited capacity to characterise vegetation.
 
It is against this background that I find it surprising that one species of daisy, namely Microseris lanceolata, was locally so common in parts of southern Australia that it was a staple food of the aboriginal people – and among the few foods that could be procured easily enough, and in sufficient quantity, to give humans an ‘insulin spike’ on a daily basis.
 
This brings me to the second aspect of this anomaly.
 
What is particularly odd about Microseris is that its growth-form seems to be odd, with no obvious explanation in terms of island biology.

South Africa has a bewildering diversity of growth-forms of Asteraceae, ranging from trees (Brachylaena) and tall shrubs (Tarchonanthus), through smaller shrubs (Metalasia) and gnarled dwarf-shrubs (Pentzia), to the usual annuals and pauciennials (often typical of disturbed soils) so typical of the family.

The asteraceous flora of South Africa even includes leaf-succulents, stem-succulents, and other bizarre growth-forms in e.g. Othonna and Senecio/Kleinia.

However, despite this remarkable genetic plasticity, the South African flora of daisies lacks, as far as I know, any species similar to Microseris lanceolata or the New Zealand representative M. scapigera.
 
What remains unclear to me is whether the foliage of Microseris is deciduous or not; and this uncertainly has limited my search for ecological analogues elsewhere.
 
I understand that Microseris is a herbaceous perennial rosette plant, with a taproot-tuber. However, do the leaves die back each year or do they remain green in the dry season?

If the leaves die back (i.e. the plant is drought-deciduous), this would make Microseris lanceolata a true geophyte, in the sense of the term used in South Africa (which as you know has an exceptional flora of geophytes even on a global scale).

However, if M. lanceolata instead retains green leaves throughout the year, this would bring it in line more with ruderal/weedy rosette herbs such as Taraxacum, which are tuberous but not geophytic in the sense that South Africans use this term (which I think is in line with Raunkiaer’s classification based on the position of the perennating buds).
 
So, is Microseris a geophyte or not? Are its leaves dry and dead during the dry season, or not?
 
Whether M. lanceolata is a geophyte or merely a perennial rosette herb with a tuber, it remains odd as an aboriginal food in the context of any comparison with southern Africa.

This is because I cannot, for the moment, recall any geophytic daisy in South Africa that was as prominent as M. lanceolata in any vegetation type (i.e. extremely common although not actually dominant of the vegetation as a whole). Furthermore, I also  cannot recall any tuberous daisy of any sort that was particularly important in the diets of hunter-gatherers in southern Africa.
 
What all of this seems to add up to is to emphasise the peculiarity of the Australian flora in a new way.

It comes as no surprise that, as Tim Low pointed out so clearly in his 1988 book, among the most important of aboriginal foods were e.g. cosmopolitan genera (often rather weedy) and  emu-dispersed fruits.

However, nothing would have prepared my mind for the discovery that asteraceous tubers were as important in aboriginal diets as they really were. e.g. on the basaltic plains of western Victoria.

This is because

• substantial/prolific tubers in general are poorly represented in Australia, compared with southern Africa (notwithstanding the bewildering diversity of small watery tubers of geophytic monocotylednonous orchids and lilies in Australia),
• the daisy flora of Australia is limited relative to that in southern Africa, and
• Microseris is an insular rather than a continental element, floristically.

There is no fauna of mole-rats in Australia. However, the habitat of M. lanceolata in places in southern Australia sounds almost suitable for mole-rats. As Low has pointed out, there was a noteworthy lack of tuber-eating mammals in the Australian fauna. Although this can usually be explained by the limited reliability and quantity of tubers in the Australian vegetation (the floristic diversity of tuberous Australian plants notwithstanding), this explanation seems to break down when it comes to Microseris.
 
(writing in progress)

Publicerat 20 augusti 2022 08.00 av milewski