December 06, 2022

Under the mediterranean-type climate, amaryllid geophytes are absent from Western Australia despite being typical in Chile, speciose in California, and diverse in South Africa


Geophytes are defined as terrestrial perennial plants of which the above-ground parts die down to ground level each year. All cryptophytes possess hidden storage organs, and geophytes are those cryptophytes other than aquatic plants or those inhabiting permanently wet ground.

The widespread family Amaryllidaceae (, which now includes Alliaceae, is mainly geophytic.

Amaryllids (

  • include some of the most spectacular and useful geophytes on Earth, and
  • are more specialised for bulbs (as opposed to rhizomes, corms or other stem-tubers) than are other geophytic monocotyledonous families.

The geophytic growth-form (see is effectively drought-deciduous. Thus, it seems particularly suited to the mediterranean-type climate, defined as having dry summers and rainy winters.

Given the above facts, it is unremarkable that various amaryllid geophytes occur under the mediterranean-type climate on various continents.

It is equally unremarkable that the local floras of amaryllidaceous geophytes are different. Only one genus is shared among the mediterranean-type climates of Chile, California, or South Africa. This is Allium, which has many spp. in California and one in South Africa.

However, what is remarkable is that (in order of most to least surprising)


Please see all the relevant genera, listed below. The most anomalous finding is the lack of any representatives in western Australia.

In California, the only indigenous genus is Allium, which in Eurasia has produced the domestic onion, chives, scallion, shallot, leek, and garlic.

I am unsure whether any species of Crinum qualifies as a geophyte. This is because this genus is associated with wet ground.


The single most powerful factor in the environment, for explaining the ecological distribution of amaryllid geophytes, is nutrient-richness, particularly the concentration of available phosphorus and zinc in the topsoil.

Wildfire is involved in this framework, because nutrient-poor soils tend to have flammable vegetation, dependent on fire for nutrient-cycling via ash.

The relationship between amaryllids and the fertility of soils helps to explain why this is the only family of monocotyledonous plants that has been agriculturally successful, as domesticated food-crops (particularly six spp. of Allium,

Of all the regions of mediterranean-type climate on Earth, that in Chile is the nutrient-richest and the least fire-prone. It can thus be seen as a 'standard' for the incidence of amaryllid geophytes, which are represented here by 11 genera.

Soils in California are nutrient-rich on alluvia, but somewhat impoverished (or imbalanced in the case of serpentine soils) elsewhere. The many spp. of Allium here cover a wide range of environments, including the Central Valley ( I know of no species with any particular relationship to wildfire.

In the small region of South Africa that has the climate in question, soils are divided between nutrient-poor (on sandstone, quartzite, and deep sand) and moderately nutrient-rich (on shale and slate). Amaryllid geophytes here are associated mainly with relatively nutrient-rich soils and vegetation somewhat protected from wildfire.

However, a few species, particularly of Cyrtanthus, show a clear relationship to fire (

Please see and

In Chile, the subterranean rodent Spalacopus cyanus ( specialises on Leucocoryne ( and and

In California, the subterranean rodent Thomomys bottae eats Allium, but only as a small part of a diet that includes greens and roots.

In South Africa, the mole-rats Georychus capensis ( and Cryptomys hottentotus specialise on the tubers of geophytes. However, amaryllids do not feature prominently in their diets. In this region, the large rodent Hystrix africaeaustralia ( - which has no counterparts in the relevant regions on other continents- may be as important as mole-rats in the consumption of the bulbs of amaryllids.



PHYCELLA (formerly Rhodophiala)















HAEMANTHUS (in part)



NERINE (in part)








AMMOCHARIS (is this really geophytic?)

Apodolirion does not reach the mediterranean-type climate



Crinum marginally present (



Posted on December 06, 2022 02:04 by milewski milewski | 14 comments | Leave a comment

December 05, 2022

Oxalis in Australia and southern Africa

In Australia, Oxalis is an unremarkable herbaceous plant. Perhaps its most remarkable aspect is the tendency for any given indigenous species to occur also in New Zealand, or perhaps South Africa, or even South America.

That is to say, the plants are in themselves unremarkable in their ecological nature, but what is remarkable is the blurring of the distinction between indigenous and introduced.

However, in southern Africa the same genus has evolved in a remarkable way, related to a regime of disturbance of the earth by animals. Here, many spp. of Oxalis bear true bulbs.

Bulbs ( are associated mainly with monocotyledonous plants. Oxalis is exceptional among dicotylodonous plants in having independently evolved bulbs.

Furthermore, the bulbs of southern African spp. of Oxalis have two major functions, viz.

  • being disseminated by disturbance, in which they act as 'vegetative seeds', and
  • serving as underground storage organs that allow adoption of a geophytic growth-form.

With the development of the geophytic growth-form, there has been a proliferation of species in South Africa, particularly under the mediterranean-type climate, that parallels the geophytic proliferation of various monocotyledonous families, e.g. Iridaceae.

The result is that the indigenous spp. of Oxalis in South Africa outnumber those in Australia 40-fold - and under mediterranean-type climates more than 100-fold.

The seed-like function of the 'aerial bulbils' of Oxalis have proven so efficient that they have greatly exacerbated the biogeographical blurring among landmasses. Various spp. of Oxalis, indigenous to southern Africa, have become cosmopolitan weeds, or have anthropogenically invaded similar climates in Australia in particular.

The result is that, perhaps more than any other lineage of plants, the South African spp. of Oxalis have come to represent a paradoxical duality. They combines exceptional local restriction in their original state with exceptional intercontinental spread in their anthropogenic state.

And - returning to the Australian occurrence of Oxalis - this leaves unanswered the puzzle of how those spp. lacking bulbils managed to spread 'naturally' among the southern continents in the first place.


presumably geophytic

Posted on December 05, 2022 20:22 by milewski milewski | 6 comments | Leave a comment

The Australian Nullarbor, bare alike of trees and geophytes - save Wurmbea, a pure floristic link with South Africa

@arthur_chapman @tonyrebelo @jeremygilmore @botaneek @troos @benjamin_walton @sedgesrock @bushbandit @reiner @adriaan_grobler @yvettevanwijk1941 @rion_c @richardgill

The Nullarbor Plain ( of southern Australia is named after its virtual treelessness.

This is an area about as large as England and Scotland combined.

This treelessness is particularly anomalous by comparison with the Great Western Woodlands (, which border the Nullarbor on its western side. These eucalypt-dominated woodlands constitute the tallest broadscale vegetation in a semi-arid climate, anywhere on Earth.

Although a few small trees of Acacia (, Pittosporum (, and Alectryon ( encroach marginally on the Nullarbor Plain, eucalypts are remarkably absent.

The odd treelessness of the Nullarbor Plain is well-known. However, what has previously been overlooked is that this is also a 'desert' for an inconspicuous growth-form category that is, in a sense, the antithesis of trees, namely geophytes (

The only geophytes recorded from the Nullarbor Plain are Wurmbea dioica ( and possibly Wumbea tenella ( (Reference: McKenzie N L and Robinson A C (1987) A biological survey of the Nullarbor region, South and Western Australia, in 1984. CALM, Australian National Parks and Wildlife Service, NP&WS, SAust. 413 pp.).

(Wurmbea, which belongs to Colchicaceae, happens to be one of the few cormous geophytes in Australia.)

This poverty of geophytes contrasts strongly with the exceptional richness of geophytes in the Little Karoo of South Africa (, which has a similar climate.

What makes this comparison all the more intriguing is that the sole genus of geophytes present on the Nullarbor Plain is also the most unqualified example of a floristic link between Australia and southern Africa.

Naturalists familiar with the southern continents will know that 'gondwanan' elements such as Proteaceae ( and Restionaceae ( are shared between Australia and South Africa (

However, such links are easily exaggerated. This is because

  • some of the families and virtually all of the genera differ between continents, in the most closely-matched types of fire-prone vegetation (kwongan vs fynbos),
  • Myrtaceae are dominant in Australia but virtually absent in relevant environments in South Africa,
  • the degrees of sclerophylly and other biological specialisations to poor soils and intense fires are greater in Australia than in South Africa, even within Proteaceae,
  • Ericaceae are surprisingly different in the form of the foliage and fruits,
  • under semi-arid climates, there is a nearly categorical difference in the incidence of non-halophytic succulents, and
  • geophytes show remarkably little similarity in floristic composition or growth-form (emphasising Orchidaceae in Australia vs Iridaceae in South Africa).

Wurmbea is one of the few clear exceptions to the above, because

Elaborating the last point:

In Western Australia, Wurmbea tends to be associated with 'granite exposures' (,inselbergs%2C%20castle%20koppies%20and%20nubbins. and and and

These environments are somewhat rejuvenated with nutrients, because of fresh weathering of the bedrock. Furthermore, the occurrence of bare sheets of rock provides some protection from the regime of intense wildfires that otherwise affects the entire landscape.

What this means is that, unlike most elements of the flora of southern Australia, Wurmbea is not particularly adapted to poor soils or intense fires. It is specialised for seasonal dormancy, but this can be seen as an adaptation mainly to the dry summers - which particularly desiccate the shallow soils on the aprons of granite outcrops.

In the southwestern Cape of South Africa, Wurmbea has a similar adaptive profile.

An association with granite is less noticeable, because granite is less widespread than in southwestern Australia, and does not form similar outcrops. However, Wurmbea likewise occurs mainly on soils of moderate status w.r.t. nutrients, and in vegetation not particularly subject to wildfire. Examples of its habitats include disturbed ground or seasonally wet depressions in renosterveld.

The above may help to explain the occurrence of Wurmbea on the Nullarbor Plain.

The soils here, derived from limestone, are neither rich nor particularly poor in nutrients. The vegetation is not free of wildfires, but the fire regime is mild because the dominant plants (particularly the amaranthaceous Maireana sedifolia, do not have flammable foliage.

One way of explaining the floristic link of Wurmbea between Australia and South Africa, therefore, is to see this genus as 'interstitial'. It characterises moderate environments, evading the ecological hegemonies imposed by kwongan and eucalypts in Australia, and fynbos and succulent karoo in South Africa.

By virtue of this lack of specialisation, the fortuitous restriction - which is poorly-described as 'gondwanan' although we lack a better adjective - of Wurmbea to two southern landmasses has peeked through. And this includes an environment - the Nullarbor Plain - where no other geophyte has prevailed.

Posted on December 05, 2022 05:52 by milewski milewski | 12 comments | Leave a comment

December 03, 2022

Geophytes (excluding Orchidaceae) in the region of Sydney, Australia

Any naturalist familiar with the region of Cape Town, South Africa, would find biological affinity with the region of Sydney, Australia.

Both locations lie at the same latitude (33.9 degrees South), and have extensive substrates of sandstone ( and

In both cases, the vegetation on sandstone slopes contains many spp. of fire-prone Proteaceae and Ericaceae. In ravines and at the coast, there are small patches of fire-free forest/thicket, containing shared genera including Podocarpus, Celtis, Diospyros, Maytenus, Elaeodendrum, Myrsine, Cryptocarya, and Cynanchum.

In view of these affinities, I was curious about the similarities and differences in the floras of geophytes (, excluding orchids.


The genus Triglochin contains geophytes, including species or subspecies restricted to South Africa ( and and and A widespread species (, occurring in the Sydney region, may qualify as a rhizomatous geophyte, despite its halophytic and aquatic affinities.


Bulbine is shared between southern Africa and Australia ( and It contains several geophytic spp. in the Cape Town region

Bulbine bulbosa ( has edible tubers, and certainly qualifies as a geophyte (pers. obs.; John Jessop, pers. comm. However, its tubers are confusingly described as roots, bulbs, or corms. Another species indigenous to the Sydney region ( is not necessarily geophytic.


Geophytic: Thysanotus tuberosus ( and and and and
Not geophytic: Thysanotus juncifolius ( and and and
Thysanotus virgatus is probably not geophytic. It is described as geophytic in, but as having perennial stems in
and and
Not geophytic: Thysanotus manglesianus (

probably geophytic and and and

Caesia parviflora
Caesia calliantha

The genus Sowerbaea contains geophytes with root-tubers. However, the only species occurring in the Sydney region, viz. Sowerbaea juncea (, is described as having fibrous roots and being restricted to 'wet soil'. I infer that it is probably not geophytic.


Burchardia umbellifera ( is root-tuberous, and qualifies as geophytic.

Wurmbea dioica
Wurmbea biglandulosa


There is a rich flora of geophytic Amaryllidaceae in the region of Cape Town.
However, the only genus shared with the Sydney region is Crinum.

Cape Town and


However, the species in the Sydney region is specialised for wet ground. It may therefore not strictly qualify as geophytic, given that geophytes are defined as fully terrestrial cryptophytes.


In the Araceae, the only species indigenous to the Sydney region that qualifies as geophytic is Typhonium brownii (

Alocasia brisbanensis ( is too aquatic to qualify as geophytic.

Gymnostachys anceps ( has 'tuberous roots', but does not qualify as geophytic, because its above-ground parts do not die down to ground level seasonally.


In the region of Cape Town, there is a bewildering proliferation of geophytic Iridaceae. This family is indigenous to the Sydney region, but the incidence of geophytes could not be more different.

The most speciose genus here, namely Patersonia, is evergreen. So are Libertia paniculata ( and Libertia pulchella (


Dioscorea is tuberous but apparently not geophytic. The species indigenous to the Sydney region is Dioscorea hastifolia (




Oxalis corniculata ('bulb absent') is the only indigenous member of this genus in this region. It is not geophytic.


Clematis has woody stems. I infer that it does not qualify as a geophyte, even if it is tuberous.

Ranunculus: some spp. tend to be aquatic, or restricted to damp ground.


The genus Euphorbia includes geophytes ( and and and and and However, the two spp. recorded in the Sydney region, namely Euphorbia drummondii and Euphorbia sparrmannii, are not geophytic.


Glycine clandestina ( and Glycine tabacina ( are both indigenous. This genus has potential for the geophytic growth-form, but neither species seems to qualify.


In the Cape Floristic Region, the genus Wahlenbergia contains at least two rhizomatous spp. (suffruticosa and subulata, that are potentially geophytic. This genus is indigenous to the Sydney region, where e.g. Wahlenbergia stricta ( is described as possessing 'tubers', and Wahlenbergia capillaris ( is described as possessing a 'thickened taproot'. Both spp. are potentially geophytic.


The widespread genus Lagenophora contains geophytes ( and and has been described as 'stoloniferous' ( The spp. occurring in the Sydney region, viz. Lagenophora stipitata (, Lagenoohora sublyrata (, and
Lagenophora brachyglossa (, are potentially geophytic.

Microseris walteri ( is well-known for its edible root-tubers. I assume that it qualifies as a geophyte.


Convolvulus is known to possess rhizomes. However, the above-ground stems tend to be woody. I assume that the spp. indigenous to the Sydney region, viz. and, are not geophytic.


For naturalists familiar with the region of Cape Town, it may seem more appropriate to focus on the region of Perth ( This is because Perth lies on a western coast, and resembles Cape Town in having a mediterranean-type climate.

However, the climates of Cape Town and Perth (32 degrees South) differ considerably, because

  • these locations differ in latitude by two degrees, and
  • the marine currents west of the coasts are cold (bringing fog) in the case of Cape Town vs warm (bringing thunderstorms) in the case of Perth.

Furthermore, all parts of Australia with mediterranean-type climates (including South Australia) have so little topographic relief that any ecological comparison with the Cape Peninsula is limited.

It is perhaps for these reasons that there is, overall, as much botanical similarity between the region of Cape Town and the region of Sydney as there is between the region of Cape Town and the regions of Perth or Adelaide.

Despite the tropical influences on the climate at Perth, the flora completely lacks certain tropical elements that reach Cape Town, in families and genera such as Ebenaceae, Apocynaceae, Sapotaceae, Metteniusaceae, and Rubiaceae.

With respect to geophytes, the tropical affinity can be seen in the occurrence of Amaryllidaceae and Araceae in the Sydney region. These families have not naturally penetrated the mediterranean-type climate in Western Australia.

Crinum occurs on alluvial landforms in the Murray Valley, and in the Flinders Range (, both in South Australia ( Both locations are marginal to the mediterranean-type climate. In Western Australia, the closest approach by Crinum to the mediterranean-type climate is near Carnarvon (

According to the Flora of Australia, Crinum in semi-arid Australia has a bulb of diameter 7-10 cm, and is restricted to 'wet places'. It occurs on clay flats in botomlands, where water tends to accumulate. However, in mesic tropical Western Australia (the Kimberley region, Crinum often occurs where the parent rock is sandstone (according to labels in the Western Australian Herbarium).

In northern Western Australia, with rainy summers and dry winters, the amaryllidaceous geophyte Proiphys (formerly called Eurycles alba) occurs on bauxitic duricrust (J S Beard, pers. comm.), as well as clay over basalt (specimen labels in Western Australian Herbarium).

Posted on December 03, 2022 11:08 by milewski milewski | 22 comments | Leave a comment

December 02, 2022

The possible adaptive value of high eyes and ears in the grey rhebok (Pelea capreolus)

@tandala @capracornelius @oviscanadensis_connerties

The eyes and ear pinnae of ungulates vary in placement, according to habitat and anti-predator strategy.

In the case of the eyes, there is variation in how far to the sides, and how high on the head, they are placed.

In the case of the ear pinnae, there is variation in how high on the head they are placed, and in how they are oriented (upright, sideways, or downwards).


An extreme example of lateral placement of the eyes is the pronghorn (Antiocapra americana):

The opposite extreme is Myotragus balearicus (, which evolved on small islands, virtually free of predators:

Turning to the placement of the eyes high on the head:

A peculiar example is Hippopotamus amphibius ( The extinct Hippopotamus gorgops was even more specialised ( and

However, there is a similar configuration in warthogs (Phacochoerus spp.,, which are the suiforms with the least affinity for water.

Warthogs live on land, but have a short neck and legs (, and kneel while foraging ( Thus, they risk not spotting danger above the grass.

In their own way, warthogs are unique in having the eyes placed above the 'horns' (


Among wild spp., an extreme example of low placement is Syncerus, in which the ear pinnae are shaded by the horns:

However, the most extreme species is a domestic one, viz. Bos indicus:

In large bovines, the function of the ear pinnae seems to be for thermoregulation as much as hearing (see


The grey rhebok (Pelea capreolus) emerges as having

  • possibly the most upright ear pinnae of any ungulate,
  • unusually - albeit not extremely - high-placed eyes, and
  • eyes as laterally-placed as in any bovid.

Please see and

How can the combination of high eyes and extremely upright ear pinnae in the grey rhebok be explained, in terms of adaptation?

It is true that the habitat of the grey rhebok is generally open, with low vegetation ( This would seem to make high placement/orientation of the sense-organs redundant.

Furthermore, the grey rhebok partly coexists with Damaliscus pygargus pygargus (, one of the most conspicuous of bovids, presumably in adaptation to open environments.

However, an apparent paradox is that the grey rhebok - in complete contrast to D. p. pygargus - has extremely inconspicuous (cryptic) colouration ( and

This is partly explained by the facts that the grey rhebok

The combination of features peculiar to the grey rhebok can be summarised as follows, relative to reedbucks.

The eyes are as high on the head, and as laterally placed, as in Redunca fulvorufula.

Compare grey rhebok ( and with R. fulvorufula (

However, the eyes are not as high-placed as in Redunca arundinum ( and and and and and and possibly Redunca redunca ( and

The ear pinnae are far more upright in the grey rhebok than in any species of reedbuck.

Compare grey rhebok ( and with R. arundinum ( and and R. redunca ( and

I suggest that this peculiar combination is consistent with the habitats and behaviour peculiar to the grey rhebok. Whereas reedbucks tend to be adapted to the tall grass of seasonal marshes, the grey rhebok is dually adapted to mature fynbos and short vegetation.

Also see

Posted on December 02, 2022 21:48 by milewski milewski | 11 comments | Leave a comment

December 01, 2022

Geophytes and other tuberous plants in woodland of Eucalyptus wandoo in southwestern Australia

The southwestern region of Western Australia, with its mediterranean-type climate, is generally flat, and nutrient-poor.

The land surface is ancient, with the most extensive laterite ( and and of any land on Earth at temperate latitudes.

However, there is a minor 'scarp' east of Perth, called the Darling Range (, in association with which some of the slopes are steep enough for the lateritic profile to have been partly eroded (

This has slightly rejuvenated the otherwise senile substrates, allowing a limited occurrence of small, herbaceous plants otherwise unable to compete with the sclerophyllous shrubs typical of the exceptionally phosphorus-poor laterite and siliceous sand (

On the slightly nutrient-rejuvenated substrates, the vegetation includes woodland of Eucalyptus wandoo ( and and The substrate is typically sandy loam over kaolinitic clay.

In this Post, I have compiled a list of the geoohytes in one study area of wandoo woodland, based on a report written for Worsley Alumina Pty Ltd. Perth (1985) Worsley Alumina Project, Flora and fauna studies, phase two. 348 pp.

I took trouble to distinguish between

  • true geophytes,
  • members of the same genera that do not qualify as geophytes, and
  • tuberous plants, of different genera, that do not qualify as geophytes.



Burchardia multiflora
in gulley

Wurmbea dioica
in gully

Wurmbea tenella
on ridge


Caesia parviflora

Chamaescilla corymbosa
in gully

Tricoryne humilis


Dichopogon capillipes
on ridge

Sowerbaea laxiflora
in gully

Thysanotus patersonii


Pauridia occidentalis
in gully

Orchidaceae (partial list):

Caladenia sericea

Cyrtostylis reniformis
in gulley

Pterostylis vittata


Ptilotus manglesii
tuberous taproot


Eryngium pinnatifidum
tuberous taproot
in gulley


Stylidium petiolare
ovoid corm, 0.15 cm diam.


Lagenophora huegelii
numerous root-tubers

Trichocline spathulata
adventitious root-tubers

TUBEROUS but apparently not geophytic:

Thysanotus tenellus

Thysanotus thyrsoideus and


Drosera gigantea
in gully, where seasonally wet
tubers of diam. up to 3.8 cm, as deep as 1 m

Drosera menziesii
seasonally moist and swamp margins

Drosera pallida

NOT GEOPHYTIC/TUBEROUS, despite belonging to the genera/families containing geophytes:

Haemodorum laxum

Platysace juncea
(tuberous taproot, but hemicryptophyte instead of geophyte)

Drosera leucoblasta

Stylidium amoenum
Stylidium affine
Stylidium caricifolium (not usually geophytic although possessing numerous root-tubers)
Stylidium dichotomum
Stylidium diversifolium
Stylidium junceum
Stylidium piliferum
Stylidium schoenoides
Stylidium uniflorum

Craspedia uniflora
(adventitious root-tubers, in gully)

Pelargonium littorale
(not tuberous)

Oxalis corniculata
(not tuberous)

Clematis pubescens
root-tuberous, but foliage perennial

Tuberous with no possibility of geophytic affinity:

Macrozamia riedlei

Posted on December 01, 2022 22:54 by milewski milewski | 7 comments | Leave a comment

Liliaceae and Melanthiaceae: geophytes present in California but not South Africa

South Africa is extraordinarily rich in geophytes, belonging to a bewildering array of families and genera.

However, these exclude two families of geophytes important in California, where the climates are similar to those of Western Cape province.

I refer to Liliaceae and Melanthiaceae.



tunicated bulbs (some spp. lack bulbs)

Calochortus catalinae



bulb of one or more fleshy scales, with or without rice-grain bulblets

Fritillaria biflora
bulb 1.5-2 cm diam., of a few fleshy scales

Fritillaria affinis
bulb of a few scales, and many 'rice-grain' bulblets


scaly bulbs or scaly rootstocks

Lilium humboldtii
bulbs ovoid, oblique 0.5-1.5 cm long


Toxicoscordion fremontii
bulb 3-6 cm long

Toxicoscordion venenosum
tunicated bulb

Posted on December 01, 2022 05:48 by milewski milewski | 1 comment | Leave a comment

November 30, 2022

Non-convergence among orchids in mediterranean-type climates in Australia and California, in the evolution of geophytes

@arethusa @catullus @tonyrebelo @ludwig_muller @jeremygilmore @botaneek @troos @benjamin_walton @afid @otes @grnleaf @bushbandit @meta4 @reiner @em_lamond @felix-insects

Geophytes are defined as perennial, deciduous, herbaceous plants which die down to ground level after each growing season, regenerating vegetatively, year after year.

This regeneration is by means of underground storage organs (, i.e. tubers, derived from either stems or roots.

According to the Raunkiaer classication, geophytes are terrestrial cryptophytes (

In southern and southwestern Australia,

See and and and

The floristic richness of orchids in Australia, under mediterranean-type climates, is remarkable: hundreds of spp. in more than a dozen genera (

Based on the above, it seems reasonable to assume that the geophytic growth-form reflects the seasonality of mediterranean-type climates, viz. those with warm dry summers and cool wet winters.

Hence, it would also seem reasonable to predict that the incidence of geophytic orchids would be similar in California, most of which has a mediterranean-type climate.

However, orchids are not mentioned in the abstract of There are many geophytes in California, but do these include orchids?

With this question in mind, I have attempted to assess the incidence of underground storage organs in orchids in California (

The following is a full list of the genera of orchids in California, according to iNaturalist.

Goodyera oblongifolia
(habitat: coniferous forests at high altitudes)
fleshy creeping rhizome
hemicryptophytic but not not geophytic

fibrous roots
(habitat: forests and dry, open hillsides)
not geophytic

Calypso bulbosa
bulb-like corm

'bulbous caudex' (e.g. and; ?root-tubers in some spp. (descriptions unclear/contradictory)
some possibly geophytic (e.g. and, but descriptions ambivalent

rhizomes absent
(habitat: marshy meadows, including at high altitudes)
Are any species geophytic in California?

creeping, fleshy rhizomes with offshoots
(habitat: streambanks)
not geophytic

fibrous creeping roots and/or rhizomes
(habitat: moist, shady places in forests)
not geophytic

Malaxis brachypoda
solid bulb ('pseudobulbous')
(habitat: moist, high altitudes)

Cephalanthera austiniae
rhizomes, not tubers
(habitat: dense forests at high altitudes)
non-green, myco-heterotrophic (
not geophytic

Zeuxine strateumatica
fleshy, creeping, above-ground rhizome, anchored by fibrous roots
possibly geophytic

coral-shaped rhizomes
myco-heterotrophic, most spp. leafless and rootless
not geophytic


What emerges is that the flora of geophytic orchids in California, even under the mediterranean-type climate, is negligible.

Calypso bulbosa and Platanthera yadonii do seem to qualify, but their categorisation as geophytes might not even occur to anyone, were it not for the search-image arising in the flora of Australia (and, to a lesser degree, southern Africa).

Furthermore, the few geophytic orchids in California - if any - that might correspond to the Australian category, in having root-tubers, are one or more species of Platanthera ( Even in this case, it remains unclear that any tubers are actually derived from roots, and that both the foliage and the inflorescence/infructescence die back during the summer.

What emerges is one of the most categorical ecological/evolutionary differences yet found among the various regions of mediterranean-type climate on Earth: a 'world-class' proliferation of geophytic, root-tuberous orchids in the case of Australia, compared with the virtual absence of such plants in the case of North America.


The genus Spiranthes is shared between California and Australia. It is geophytic in Australia, and at least one species may be geophytic in California. However, note that the genus has hardly penetrated the mediterranean-type climate in Australia.

The genus Zeuxine is also shared between these two continents ( However, in this case the climatic difference is even greater than in Spiranthes.

Posted on November 30, 2022 20:58 by milewski milewski | 10 comments | Leave a comment

Geophytic flora of Wongan Hills Nature Reserve, southwestern Western Australia and

Kenneally 1977

Mediterranean-type climate
Mean annual rainfall 390 mm

Total vascular flora 409 spp.

Geophytic flora 33 spp. (= 8% of flora, consisting mainly of orchids)

Pauridia occidentalis 'ephemeral' (probably actually geophytic), damp areas of gulley, in woodland of Eucalyptus loxophleba over Acacia acuminata


Arthropodium capillipes 'ephemeral' (probably actually geophytic), damp red soil in woodland of Eucalyptus loxophleba over Acacia acuminata

Thysanotus patersonii widespread

Thysanotus sp. rare, hill slope


Caesia parviflora 'ephemeral' (probably actually geophytic), common in damp areas, in woodland of Eucalyptus loxophleba over Acacia acuminata and

Chamaescilla corymbosa damp red soil

Bulbine semibarbata 'ephemeral' (probably actually geophytic), red clay, in woodland of Eucalyptus loxophleba over Acacia acuminata


Wurmbea tenella damp ground

Wurmbea sp. red clay over greenstone rock


18 spp. occur here.
all occur on lateritic substrates, in kwongan vegetation, as well as alluvial soils in the gulley, and in woodland of Eucalyptus salmonophloia
Caladenia 8 spp.
Diuris 1 sp.
Eriochilus 1 sp.
Lyperanthus 1 sp.
Pterostylis 6 spp.
Thelymitra 1 sp.


Stylidium caricifolium laterite

Platysace cirrosa 'tuberous climber', tubers (diam. 5 cm) edible, on red soil of apron of breakaway
Platysace maxwellii kwongan


Drosera aff bulbosa greenstone scree
Drosera macrantha laterite
Drosera macrophylla damp red soil
Drosera menziesii kwongan
Drosera aff stolonifera kwongan
Drosera zonaria kwongan


Ptilotus spathulatus prostrate herb, common on alluvial substrates (is this geophytic?)

On yellow sand, there is tall shrubland of Acacia blakelyi and spp., Callitris arenaria, Banksia prionotes, Banksia attenuata, Hakea platysperma, Xylomelum angustifolium, Allocasuarina campestris, etc. This community contains 6 spp. of Drosera (including geophytes, e.g. D. menziesii), Thysanotus patersonii, and 'quite common' orchids, namely Caladenia 2 spp., Diuris longifolia (, Pterostylis recurva, and Lyperanthus nigricans.


Caesia is a genus shared among Australia, Madagascar, and the Cape Floristic Region of South Africa. It is root-tuberous. However, the development of the tubers is minimal in C. parviflora.

Anigozanthos (Haemodoraceae) does not qualify as geophytic, because the above-ground parts do not die back to ground level in the dry season. Anigozanthis humilis is common in kwongan in Wongan Hills Nature Reserve.

This is an adequate reference for the lack of geophytes in succulent saline vegetation in Western Australia.

Posted on November 30, 2022 10:23 by milewski milewski | 4 comments | Leave a comment

Some aspects of aboriginal diets in southwestern Australia and southern Africa, with particular reference to tubers in mediterranean-type climates

@tonyrebelo @jeremygilmore @yvettevanwijk1941 @sedgesrock @nicky @robertarcher397

In August 1984, I discussed aboriginal diets with the late Sylvia Hallam ( and the late Hilary Deacon (

The following is a transcript of my notes at the time.


The aboriginal population of Australia was remarkably sparse: possibly less than 0.5 million on the whole continent.

Dioscorea hastifolia ( is an indigenous liane. It occurs in a habitat-duality which I have found repeatedly for various spp. of plants: granite outcrops and alluvial banks.

In the relatively nutrient-poor landscapes of southern Australia and southern Africa, both situations - although at opposite ends of the catena - are somewhat enriched, the first by fresh weathering, and the second by concentration via the flow of water.

On alluvial banks, D. hastifolia grew in 'thickets' of Jacksonia sternbergiana ( and, an extremely sclerophyllous, nitrogen-fixing tall shrub or low tree. The liane also climbed on the extremely sclerophyllous cycad Macrozamia riedlei (, another nitrogen-fixer.

In southwestern Western Australia, D. hastifolia occurred in local 'colonies', which were anthropogenically maintained free of the fires otherwise ubiquitous in the area. In these 'colonies', there were permanent 'rabbit-warren' holes dug by aboriginal people, to a depth of several metres in places. The repeated and intensive harvesting was tantamount to a kind of culturing of the food-plant, but did not qualify as domestication, because there was no selective breeding.

Some patches of Dioscorea were fairly extensive, viz. several hundred metres in diameter. Examples occurred at Upper Swan (,_Western_Australia), where D. hastifolia formed fire-protected foci within woodland of Eucalyptus rudis (, which was otherwise regularly burned by the aboriginal people.

Alluvial substrates were particularly supportive of the aboriginal people, partly because of the proximity of Typha domingensis ( and Typha orientalis (, with their edible rhizomes.

The tubers of D. hastifolia have diameter 1.3-4 cm and length up to 60 cm. This large size meant that they were economical to excavate, compared to the other tubers in this flora, all of which are small.

The aboriginal people also ate the unpalatable bulbs of Haemodorum (, an element of the kwongan flora, associated with extremely nutrient-poor sandplains.


Underground storage organs of plants are available for much of the year, and easily found by virtue of the dried above-ground traces. They tend to be unavailable only at that time of year when fleshy fruits are most available, namely autumn (March-May).

In the southwestern Cape of South Africa, the aboriginal hunter-gatherers depended mainly on geophytes.

Several of the 14 South African spp. of Diiscorea reach occur in the Fynbos Biome (, and one ( occurs in the mediterranean-type climate. However, there seems to be no knowledge of any species of Dioscorea in the aboriginal diets. (@yvettevanwijk1941 ?)

Here, corms of Watsonia ( were the main food, in places. This food is starchy, containing less protein than e.g. domestic potato (Solanum tuberosum).

This - the rapid spread of Watsonia as an invasive weed in southwestern Australia notwithstanding (,regrow%20from%20corms%20and%20seeds) - was a slowly-renewing resource, the harvested corms taking up to 4-5 years to be replaced.

Watsonia shoots foliage in late autumn, and grows by depleting the corm, while simultaneously dumping wastes in it, causing it to turn reddish, bad-tasting, and inedible. Then the new corm grows above it, pale and palatable, with minimal tannins, while the above-ground parts die down to leave a good, pale, edible corm in the ground over the summer.

For these reasons, autumn/early winter was really the only time when Watsonia corms were available to the aboriginal hunter-gatherers.


Please see

I find it remarkable that a genus poorly represented in Western Australia compared to South Africa, namely Dioscorea (Dioscoreaceae), was perhaps the most important of the stem-tuberous foods in the mediterranean-type climate in this state, while the category of cormous Iridaceae, so common and diverse in southwestern South Africa, was unavailable under similar climates and on similar soils in southwestern Australia.

There is only one geophytic member of the Iridaceae in southwestern Australia, namely Patersonia babianoides ( However, even this species only marginally/nominally/technically qualifies as a geophyte, because its above-ground parts hardly die down in summer, and the storage organ is merely a corm-like rhizome, hardly qualifying as food for humans, and scarce in the vegetation anyway.

Posted on November 30, 2022 06:03 by milewski milewski | 3 comments | Leave a comment