Archivos de diario de febrero 2022

04 de febrero de 2022

Proteas with fleshy fruits: a glimpse at the time of dinosaurs?

@hualo @ludovica_ @nitsuga74 @eitel @sur_endemico @nodora @alejandro_karelovic @mark_smale @lloyd_esler @dave_holland @chrise @arthur_chapman @pjd1 @troos @vynbos @cco @rowan_hindmarsh_walls @shauns @botaneek @chris_whitehouse @muisvoel @charles_stirton @adriaan_grobler @graham_g @benjamin_walton @seth @carber @tiggrx @sp_bester @sandraf @andrewm @justinhawthorne @felix_riegel @leejones @annsymons

Proteaceae are so ancient that they coexisted with 'dinosaurs' for at least 25 million years (e.g. see This is a period of presumable coevolution with archosaurs longer than the combined Miocene, Pliocene and Pleistocene.

It therefore seems fair to assume that various species of proteas were dispersed and sown by 'dinosaurs' during the Cretaceous.

The presumed mutualism is so archaic that we might have been left with no trace of it in the modern world.

And indeed in southern Africa, where Protea cynaroides is the national flower (,cynara%27%20(the%20artichoke).) and the Cape Floristic Region ( is renowned for several genera of subfamily Proteoideae, there is no species of protea with fleshy fruits (see

However, the circumstances on several other landmasses have been such that perhaps as many as 20 genera of proteas remain reminiscent of the ancient syndrome.

And it may come as a particular surprise to South African naturalists that proteas with fleshy fruits include:

The role of dispersing and sowing proteas with fleshy fruits has been inherited by various mammals, birds and reptiles. However, no protea has adapted to the modern world to the extent of having fleshy fruits attractive mainly to the relatively small passerine birds - such as Turdidae and Pycnonotidae - typically associated with the consumption of ripe fleshy fruits in Africa, Asia and the Americas.

The main continent retaining proteas with fleshy fruits is Australia. Here, about 110 species, in four subfamilies (Persoonioideae, Grevilleoideae, Proteoideae and Bellendenoideae), have fleshy fruits and seed-dispersal by archaic birds and mammals. These plants vary 150-fold in height from shrubs reaching only 20 centimeters (e.g. see to trees reaching 30 meters, but the fruits tend to fall to the ground when ripe regardless.

In Australasia, the main agents of dispersal and sowing seem to be the emu (Dromaius novaehollandiae, and cassowaries (Casuarius spp.,

However, marsupials ( and, certain large passerine birds ( and large skinks (e.g. and;database=;collection=;brand=default;;query=tiliqua) also participate in the case of Persoonia (

Only one species of protea with fleshy fruits remains in South America (, associated with the understorey of forests/woodlands of Nothofagus. It is surprising that the agents of dispersal and sowing remain unknown, because its ripening to red ( makes this one of the brightest-hued on Earth of all the fruits of proteas.

New Zealand, too, retains only one species of protea with fleshy fruits ( Here the likely agents were extinct moa (

On other Pacific islands, "Weston and Crisp (1996) consider the fruits of Virotia, Kermadecia, Turrillia, and Sleumerodendron to be typical bat fruits, with their dull color, sour or mildly sweet odor, lack of protective rind, and possession of large hard parts." (See page 846 in

Most of the proteas with fleshy fruits are odd w.r.t. either their survival post-dispersal (grevilleoids) or their germination (persoonioids).

A puzzling aspect of the grevilleoid species is that their relatively large seed-kernels tend to be free of toxins, and thus edible to humans.

A puzzling aspect of the persoonioid species - which unlike the relevant grevilleoids are adapted to wildfires and nutrient-poor soils - is their slow and unpredictable germination (e.g. see and Nonetheless, certain species of Persoonia regenerate only germinatively (see section 6.4 in

The following compendium of illustrations is arranged in alphabetical order by genus and species. In addition Garnieria spathulifolia (,at%20Prony%20Bay%20in%201868%E2%80%931870%20by%20Benjamin%20Balansa.), some species of Heliciopsis (see and Bleasdalea may qualify.

Acidonia microcarpa: no photos available

Athertonia diversifolia

Bellendena montana: no photos of fruits available despite the many photos of flowers

Catalepidia heyana

Cenarrhenes nitida

Gevuina avellana

Helicia: this genus includes species with fleshy fruits and species in which the fruits ripen dry and brown.

Helicia australasica

Helicia cochinchinensis

Helicia glabrifolia

Helicia nortoniana

Hicksbeachia pinnatifolia

Kermadecia: no photos available

Persoonia: all of the approximately 100 spp. have fleshy fruits, but most do not change from green when ripe, instead falling to the ground in a state in which the fruit-pulp is green, moist and relatively soft.

Persoonia spp. indet.

Persoonia falcata

Persoonia gunnii

Persoonia juniperina

Persoonia lanceolata

Persoonia linearis (seed mass about 1.9 grams)

Persoonia mollis

Persoonia muelleri

Persoonia pinifolia

Persoonia silvatica: Floyd (1989) states on page 296: "Drupe, purplish lemon-green...15-18 mm diameter. Flesh edible, mucilaginous and fibrous, tasting like passionfruit."

Persoonia virgata

Sleumerodendron: no photos available

Toronia toru

Triunia youngiana

Turrillia: no photos available

Virotia: no photos available

Publicado el febrero 4, 2022 09:04 TARDE por milewski milewski | 16 comentarios | Deja un comentario

08 de febrero de 2022

Leaf-spinescence in Orites, an intercontinental genus of proteas

@tonyrebelo @gregtasney @nyoni-pete @fionagumboots @nigelforshaw @nicfit @kenharris @ninakerr01 @chrisclarke25 @nicklambert @arthur_chapman

Leaf-spinescence - which is perceived as 'prickly' (i.e. somewhat painful) on human skin - occurs on all vegetated continents.

However, it is most noticeable in Australia. This is partly because sclerophylly (lignification of the foliage, is extremely well-developed on this continent.

In Australia (see page 408 in and ):

  • an exceptional number of species are leaf-spinescent,
  • extensive vegetation types are dominated by leaf-spinescent plants (particularly Triodia,, and
  • most of the leaf-spinescent species belong to genera restricted to this continent.

This is exemplified by Proteaceae.

There are so many leaf-spinescent species of Proteaceae in Australia that it would be hard to count them all. By contrast there are none in either Africa or South and central America, despite the indigenous occurrence of 14 genera in the former and at least five genera in the latter.

The proteaceous genus Orites is worth focussing on because:

  • it has a disjunct 'Gondwanan' distribution, shared between Australia (6 species) and South America (2 species), and
  • its Australian species vary extremely in habitat, and the size and shape of their leaves.

It is true that Orites:

However, what seems to emerge is that the leaf-spinescent species of Orites occur only in Australia, varying in the position of the sharp features on the leaves.

The eight species of Orites can be categorised as follows:

  • two species in South America (fiebrigii of Bolivia and myrtoideus of Chile), neither of which seems to be leaf-spinescent,
  • two species in Australia (lancifolius and revolutus) which are not leaf-spinescent despite being somewhat sclerophyllous,
  • two species in Australia (milliganii and acicularis) which are sclerophyllous and leaf-spinescent (in different ways from each other), and
  • two species in Australia (diversifolius and excelsus), both of which vary from shrubs to trees and have complex patterns of variation in leaf-form.

In the case of the two last-named species, there is leaf-spinescence (albeit weak) in at least some of these forms. This applies particularly to 'juvenile' foliage in the case of the rainforest tree Orites excelsus.

Within Orites in Australia, there is:

  • a ‘kwongan-like’ ( pattern in the shrub genera of alpine Australia, with an emphasis on sclerophylly in wildfire-prone vegetation, which in some species extends to leaf-spinescence, and
  • a ‘rainforest-like’ pattern aligned with e.g. Macadamia (, in which the vegetation is free of wildfire but any leaf-spinescence is more associated with 'juvenile' foliage.

Neither O. milliganii nor O. acicularis dominates vegetation. However, they collectively make for a considerable element of leaf-spinescence in the alpine vegetation of Tasmania. This contrasts with the situation in mainland alpine Australia where the local species of Orites, namely O. lancifolius, is not leaf-spinescent and instead closely resembles O. myrtoideus of Chile.

A third species common in heathland in alpine Tasmania, namely O. revolutus, is not leaf-spinescent. However, as a classic example of evolutionary convergence, it has similar foliage to the daisy Olearia ledifolia ( Furthermore, another species of Olearia, also growing in similar habitats, does qualify as leaf-spinescent (

Is there any other continent on which proteas and daisies, growing side-by-side, have such similar foliage that they can be confused by naturalists (

The following illustrate the species in alphabetical order (note that Orites megacarpus has been transferred to a genus of its own,

Orites acicularis, of heathlands in Tasmania, has needle-like leaves qualifying as leaf-spinescent in a simple design.

Orites diversifolius of Tasmania occurs across a range of vegetation types, and varies from shrub to tree. Its leaves are variable but in at least certain situations it seems to exhibit (weak) leaf-spinescence. I do not know how much of this variation is between 'juvenile' and 'adult' foliage, as opposed to being habitat-based.

Orites excelsus is the ‘forest tree’ in the genus, growing up to 30 meters high. It shows complex heteroblasty, with the seedling leaves, 'juvenile' leaves and 'adult' leaves all different ( In the 'juvenile' foliage the leaf tends to be pinnasect and toothed. I infer, from the common name ‘prickly ash’, that the teeth sometimes qualify as leaf-spinescent (probably always weakly so, much as in genus Macadamia).

Orites fiebrigii (Bolivia; no close-up photos of the leaves are available)

Orites lancifolius

Orites milliganii is a shrub of the high-altitude heathlands in Tasmania. It is certainly sclerophyllous, and although the spines on the leaves do not look particularly sharp I think this species qualifies as leaf-spinescent.

Orites myrtoideus (Chile)

Orites revolutus

Publicado el febrero 8, 2022 02:14 MAÑANA por milewski milewski | 3 comentarios | Deja un comentario

10 de febrero de 2022

How do we make sense of leaf-spinescence in Podocarpus?

@npk @nicfit @coenobita

Among conifers, leaf-spinescence occurs in certain species in the genera Picea (, Juniperus (, and Araucaria (

It also occurs in a few species of Podocarpaceae, a family occurring mainly in the Southern Hemisphere.

There are 19 genera of podocarps ( The only leaf-spinescent species are several species of Podocarpus and Saxegothaea conspicua.

These can be categorised as follows:

  • New Zealand: Podocarpus totara (tree), Podocarpus laetus (tree) and Podocarpus acutifolius (shrub),
  • southeastern Australia: Podocarpus spinulosus (shrub), and
  • South America: Podocarpus nubigenus (tree, surprisingly similar to totara var. totara of New Zealand), Podocarpus parlatorei (tree), Podocarpus glomeratus (tree), Podocarpus lambertii (tree), and Saxegothaea conspicua (tree).

The biogeographical picture that emerges:
Podocarpus is widespread on southern continents and across the equator to China, Japan and central America. However, it is leaf-spinescent only in South America and southeastern Australasia.

If leaf-spinescence is defensive against folivory, we might expect it to occur mainly:

  • in shrubby species,
  • at the sapling stage of tree species, and
  • in regions with relatively intense folivory.

In podocarps, leaf-spinescence is not particularly associated with shrubby species, thus contradicting predictions.

There is scant information on how leaf-spinescence changes as plants grow from seedling through sapling to mature tree. However, at least in Podocarpus totara it does seem to be true that it is particularly associated with the sapling stage.

With respect to intensity of folivory, no clear trend is apparent.

Kevin Burns has hypothesised that, in Podocarpus in New Zealand, leaf-spinescence shows adaptation to extinct moa ( and

In southern Africa, folivory is particularly intense, and the species of podocarps include both shrubs (Podocarpus elongatus and P. henkelii) and trees (particularly Podocarpus latifolius). Contrary to predictions, no species is leaf-spinescent and P. latifolius is virtually ignored by mammalian folivores - including the savannah elephant (Loxodonta africana) - even at the sapling stage (see

Southwestern Western Australia is exceptionally rich in leaf-spinescent plants (particularly shrubs), yet Podocarpus is not leaf-spinescent.

The only podocarp occurring here, Podocarpus drouynianus (, is specialised as an understorey shrub - never growing taller than 3 meters - in combustion-prone forests of eucalypts. It regenerates from the roots, and fruits only after wildfire. One of its common names hints that its foliage is actually fire-promoting owing to its ‘resin’ content, and if so this is remarkable in a genus generally associated with wildfire-free environments.

The lack of leaf-spinescence in P. drouynianus suggests that podocarps do not follow the ecological patterns set by other leaf-spinescent plants in general.

The explanation suggested by Burns for leaf-spinescence in New Zealand does not seem to apply in South America, where there have been no counterparts for moa.

So it seems that we need to rethink, from scratch, why certain podocarps are leaf-spinescent and why these species mirror each other, approximately, in New Zealand and South America.

The following illustrations of the leaf-spinescent species of podocarps are arranged in alphabetical order.

Podocarpus acutifolius (New Zealand)

Podocarpus glomeratus (South America)

Podocarpus laetus (New Zealand)

Podocarpus lambertii (South America)

Podocarpus nubigenus (South America)

Podocarpus parlatorei (South America)

Podocarpus totara (New Zealand)

Podocarpus spinulosus (southeastern Australia)

Saxegothaea conspicua (South America)

Also possibly leaf-spinescent:
Podocarpus sprucei

Publicado el febrero 10, 2022 09:55 MAÑANA por milewski milewski | 9 comentarios | Deja un comentario

13 de febrero de 2022

Plasticfruits, part 1: How an ordinary daisy becomes extraordinarily fruity

@chris_whitehouse @peterslingsby @lloyd_esler @adriaan_grobler @botaneek @graham_g @vynbos @troos @benjamin_walton @nicky @craigpeter @jon_sullivan @yvettevanwijk1941 @magdastlucia @joeysantore @alastairpotts @seanprivett @strandloper @arthur_chapman @fynbosphil @henrydelange @qgroom @carinalochner @adrianfigueroa

I have noticed a principle in the biology of plants ( that seems missing from textbooks.

Ponder the scientific implications of the observation that 'flower' ( is less ambiguous than 'fruit' (

The principle emerging from this is:
Flowers tend to be evolutionarily fixed, but fruits tend to be evolutionarily plastic.

This is why it is better to classify, and easier to identify, plants by their flowers than by their fruits.

It is also why the word 'flower' is less confusing, in botanical descriptions, than the word 'fruit'.

'Fruit' technically includes dry, dehiscent/ballistic pods and capsules, papery to woody follicles, and diverse other structures. These include compound structures incorporating calyces, peduncles, hypanthia, etc., and can contain from one seed to hundreds. However, 'fruit' is usually taken to mean something closer to the category of fruit in human diets.

Another way of saying this is that plants tend to be conservative in their sexual organs, but versatile in their organs of seed-dispersal. Or relatively fixed vs relatively modifiable. Fruits seem more adaptable than flowers within any given evolutionary lineage.

In this series of Posts, I focus on various examples of this principle at the level of genus (

So many genera, worldwide, illustrate the principle of 'plasticfruits' that my choices must be arbitrary. However, I would like to show diverse ways in which fruits have converged, evolutionarily in producing enough 'fleshiness' to provide edible rewards for seed-dispersing animals.

I start with simple - but surprising - examples, building to morphologically more complex examples.

My first choice is the daisy genus Osteospermum (, which occurs mainly in southern Africa.

The fruit in Osteospermum, as in other daisies (Asteraceae), is a cypsela ( containing a single seed. It is often stated that daisies bear achenes but this is, strictly speaking, incorrect. A cypsela is similar to an achene but differs technically in the number of carpels (

It is the modification of the exocarp, or outer layer, of the cypsela that provides the main variation - which can be surprisingly eye-catching - in the fruits of various species of Osteospermum.

In some species, the cypsela bears three small wings plus an apical air-chamber, facilitating dispersal by wind. These species tend to occur in dry environments. I do not know whether the wings develop from the exocarp or from the calyx, but I suspect the former.

The fruit is this case would be described by most naturalists as a seed. It is actually a seed contained in the dead, dry carpels, but equates to a seed for practical purposes. (When you shuck a sunflower 'seed', discarding the hull to obtain the real seed inside, you are actually handling a whole fruit of Helianthus,

In other species such as Osteospermum spinosum ( and, the cylindrical cypsela has no wing but its exocarp is thinly fleshy. This provides a meagre food-body designed to be eaten by ants as a reward for dispersal and sowing by these insects ( and

The fleshy layer is thin and colourless, and not noticeable to the human eye. The fruit is not displayed but dropped to the ground immediately on ripening. If the fallen cypsela is not immediately collected by ants, the exocarp dries out and wrinkles within days or perhaps hours.

Here is another example: Osteospermum asperulum ( Also see

The structure described above is, again, a fruit in botanical terms but would not be described as such colloquially.

In yet other species, the cypsella is ribbed and/or pitted, or kidney-shaped, warty and pitted. The adaptive significance is unknown but this shows how variable the diaspores ( are within this single genus.

Finally, in a few species of Osteospermum the exocarp of the cypsela is fleshy enough to form something clearly recognisable as a fruit ( - and one that is perfectly edible for humans albeit too small and fiddly for most naturalists to bother with.

In these cases, the exocarp is thick and succulent enough to provide a jam-like reward to birds that swallow the whole cypsela, digest the sugary exocarp, and defecate or regurgitate the seed contained in it, which remains intact after digestion.

The cypsela in these cases not only conforms to the search-image for an edible, fleshy fruit, but changes in hue to present a pre-ripe display. The sequence, from green through yellow and red to blackish, flags to birds the imminent availability of the ripe, palatable exocarp.

The important point:
The flowers of all these species are similar, and unremarkable for daisies. Yet the fruits vary categorically in appearance and function, and this is achieved by evolutionary modification of a single part of the fruit: the exocarp.

If taxonomists were to use the fruits for classification, they would split Osteospermum into different genera. But what fits the evidence better is that this is one genus, with 'plasticfruits'.

The following illustrate the flower-heads, fruits and seeds of Osteospermum moniliferum ( This is dispersed mainly by birds but is one of the few species of daisies, worldwide, that presents fruit-flesh fully edible for humans.

In my experience, the fruits are best eaten when black, at which stage the fruit-pulp has changed from coherent/crisp to fluid. The taste is sweet with no sourness or astringency. I collect about 40 at a time in my mouth, burst them with my tongue one by one, swallow the jam, and spit out the seeds as I go along. I am hardly an agent of dispersal because my instinct is not to swallow the seeds, and I tend to linger at individual plants laden with fruit.

The sequence of colours is as follows. The nearly full-size, but still completely unripe fruits are leaf-green with a purple blush. The full-size but unripe fruits are dull yellowish green. The ripe fruits are brown. The fruit actually shrinks from the yellowish stage to the fully ripe stage, without wrinkling. The fruit-pulp seems to lose some bulk in the conversion from the turgid (still hardly sweet) fruit-pulp at the yellowish stage - which I find myself spitting out rather than eating it - to the ripe, jammy stage.

The following shows that the composite flower-heads are similar to those of thousands of species of daisies worldwide:

The following show that a limited number of the flowers on each flower-head produce fruits, owing to constraints on space:

The following show the development of hues in the pre-ripe display:

The following show the fully-ripe fruits:

The following show the seeds divested of fruit-pulp by digestion or weathering:

to be continued in

Publicado el febrero 13, 2022 10:12 TARDE por milewski milewski | 10 comentarios | Deja un comentario

15 de febrero de 2022

The West African fauna has lacked not only zebras but also grazing rodents

@maxallen @douglasriverside @oebenin @galat-luong_anh @galewski @zarek @tom_crassard @elisebakker @tandala @oviscanadensis_connerties @jeanpaulboerekamps @mschmidt1966 @i_c_riddell @ricky_taylor @ludwig_muller @jason_van_den_berg

Zebras (Equus spp.) are absent from West Africa (, despite the presence of up to five species in southern and eastern Africa over the past ten thousand years.

It is easy to assume that this absence is because zebras were:

  • formerly present but have been exterminated, and/or
  • ecologically replaced by an extinct form of wild ass.

However, there seems to be no palaeontological or archaeological evidence of zebras anywhere in West Africa - even in the Pleistocene.

Human populations have long been denser in West than in southern Africa, and this is known to have drastically reduced the geographical ranges of wild ungulates - in several cases to the point of near-extermination from West Africa. However, even the giant eland (Taurotragus derbianus) and a giraffe (Giraffa camelopardalis peralta) still remain in small numbers.

It is likely that a form of wild ass, now extinct owing to human influence, formerly occurred in the western Sahel ( However, this would still leave a large area of savannah ( - as extensive as the whole of South Africa - naturally devoid of wild equids.

The point of this Post is that a similarly puzzling absence also applies to certain members of the grazing guild that are so fecund that their extermination by humans has been out of the question.

Otomyin murids ( are common and diverse in southern Africa and are specialised for fibrous foods similar to the diets of zebras and asses.

Otomys, Myotomys and Parotomys resemble voles ( and tropical American grazing rats (, and They are among the most strictly herbivorous of rat-like, non-amphibious rodents.

The jaws of otomyins are noticeably massive ( and and and their molars are adapted for grinding fibrous greens (

Two of the many species of otomyin rodents do marginally reach West Africa: Otomys occidentalis and Otomys burtoni ( However, these are disjunct relative to the distribution of the rest of the genus, the closest species of which occurs in northern Angola, two thousand kilometers away.

In addition, a large-bodied grazing rodent, Thryonomys gregorianus (, is widespread in eastern Africa from southern Zimbabwe northwards - but hardly reaches West Africa.

The absence of these specialised grazing rodents from West Africa can hardly be attributed to human influence. Therefore there seems to be something fundamental in the ecology of this region that has limited the niches of non-ruminant grazers.

The only two species of specialised grazing rodents widespread in West Africa, namely Thryonomys swinderianus ( and and Dasymys rufulus (, are:

  • largely restricted to the vicinity of permanent water, and
  • shared with southern Africa at the level of species (T. swinderianus) or genus (Dasymys).

Arvicanthis niloticus solatus ( and Arvicanthis ansorgei ( fill In ecologically for otomyins to some extent in West Africa, having similar body mass (approximately 100 grams) and eating grasses as staples. However these rats are not as specialised as otomyins and do not resemble voles.

What emerges is an anomalous lack of both zebras and grazing rodents in West Africa.

And, come to think of it, is there any evidence for that even larger specialised grazer, the square-lipped rhino (Ceratotherium simum,, occurring in West Africa - even in the Pleistocene?

Can any reader propose a reason why wild grazers across this large range of body sizes (100 grams to two tonnes) have been unsuited to the savannahs of a wide swathe of Africa from Senegal through Burkina Faso to eastern Nigeria?

Publicado el febrero 15, 2022 02:46 MAÑANA por milewski milewski | 3 comentarios | Deja un comentario

16 de febrero de 2022

The flora of southern Africa is not diverse enough to emulate hollies, part 1

@ludovica_ @eitel @nodora @mark_smale @dave_holland @chrise @arthur_chapman @pjd1 @troos @vynbos @cco @rowan_hindmarsh_walls @shauns @muisvoel @charles_stirton @adriaan_grobler @graham_g @benjamin_walton @seth @carber @tiggrx @sp_bester @sandraf @andrewm @justinhawthorne @felix_riegel @leejones @annsymons @chris_whitehouse @lloyd_esler @botaneek @nicky @craigpeter @jon_sullivan @magdastlucia @joeysantore @alastairpotts @seanprivett @strandloper @fynbosphil @henrydelange @francoisdurandt @gregtasney @martinbennett @russellcumming @marcoschmidtffm

European holly (Ilex aquifolium,, and see also and North American holly (Ilex opaca, are well-known for mainly non-biological reasons.

(Other similar species occur in China, Taiwan, Mongolia, Korea and Japan: and and

These plants happen to be evergreen and they happen to have cheerfully ruddy fruits, which remain attached during winter (

Hence they have acquired symbolic meaning, around Christmas, when the rest of the vegetation is drab (

However, when viewed through the lens of a naturalist, the familiar hollies of the Northern Hemisphere represent a noteworthy combination of adaptive features. This combination has also arisen - owing to evolutionary convergence - under completely different identities in other floras around the world.

The familiar hollies combine the following two adaptations:

Leaf-spinescence is ecologically significant because it tends to occur in plants adapted to nutrient-poor soils, where foliage tends to be so fibrous that it is unpalatable. Such plants tend to be adapted for consumption by combustion rather than by animals.

(For flammability of hollies see and

Bright-hued, succulent fruit-pulp is ecologically significant because it tends to occur where vegetation is protected from intense wildfires, there is accumulation of organic matter in the soil, and potassium is consequently plentiful ( and

There is obviously some incongruity between nutrient-poverty and potassium-richness, and between flammable and wildfire-free situations.

For this reason, the niches for plants combining leaf-spinescence with fleshy fruits tend to be restricted, and these plants are ecologically noteworthy wherever they occur.

to be continued...

Publicado el febrero 16, 2022 12:14 MAÑANA por milewski milewski | 11 comentarios | Deja un comentario

17 de febrero de 2022

The flora of southern Africa is not diverse enough to emulate hollies, part 2

One of the overlooked aspects of the flora of southern Africa - which is renowned for its phylogenetic diversity ( - is a lack of any counterpart for the familiar hollies. That is to say, for any species combining leaf-spinescence with fleshy fruits.

In various ways, this lapse is a case of 'so near and yet so far'.

For example:

The species closest to qualifying is Drypetes natalensis ( and and, which belongs to Putranjivaceae. The 'juvenile' leaves are toothed but not quite rigid enough to be called spinescent, and the fruits are fleshy but tend to wrinkle and harden when ripe. Less ambivalent is a congener in the Caribbean, Drypetes ilicifolia (

The failure of southern African floras to produce any species unambivalently combining leaf-spinescence with fleshy fruits can best be understood by comparison with Australia, where climates and soils are most aligned.

Even in Australia, the area with winter-rainfall and dry summers virtually lacks species with the combination in question. This is clearest in Ericaceae. Several endozoochorous ( genera occur in Western Australia, but the fruits are small and dull, and more attractive to ants than to seed-dispersing birds.

It is only in the eastern states of Australia - where the soils are slightly richer and rainfall occurs in both summer and winter - that the combination shifts towards recognisable form (e.g. and The most spectacular examples are in gents Leptecophylla (

The ericaceous genus Leucopogon nicely exemplifies this pattern. Under a winter-rainfall climate, several species are leaf-spinescent, and one species has bright-hued fleshy fruits ( However, no species combines these features - the closest being Leucopogon parviflorus ( with its small whitish fruits.

It is eastward - where rain falls year-round and a degree of geological uplift has slightly rejuvenated the soils - that the combination arises ( and and and and

Whereas transitional climates and soils cover an extensive area in five states of Australia, they cover only a small area in South Africa, mainly in Eastern Cape province ( The chances of a suitable niche arising have been correspondingly greater in Australia than in southern Africa.

And so even a flora as diverse and phylogenetically resourceful as the Cape Flora - producing one of the floristic 'kingdoms' of the world - has not found a suitable opportunity for evolutionary convergence with the familiar hollies of the northern hemisphere.

Publicado el febrero 17, 2022 12:34 MAÑANA por milewski milewski | 2 comentarios | Deja un comentario

18 de febrero de 2022

List of species combining spinescent leaves and bright-hued fleshy fruits in Australia

(Also see

There are probably more species of plants combining leaf-spinescence and fleshy fruits in Australia than on any other landmass (see

However, it is as yet difficult to list the Australian species definitively.

This is because:

  • the flora is so diverse that several species are incompletely documented (e.g. in Persoonia),
  • both leaf-spinescence and the fleshiness and bright colouration of fruit-pulp are marginally expressed in many clades,
  • leaf-spinescence may be subject to heteroblasty and/or induced by herbivory, and
  • in Ericaceae, there is a bewildering complex of epacridoid genera that overlap in many features.

Note that in the genus of hollies, Ilex arnhemensis (Aquifoliaceae) is the only species indigenous to Australia. Its leaves are not spinescent.

The following provisional list is arranged alphabetically. Parentheses indicate species that qualify only ambivalently, because the leaves are not clearly spinescent and/or because the fruits are relatively small and dull-hued.


Alyxia oblongata and and

Alyxia ilicifolia

(Alyxia orophila has weakly spinescent leaves and and and

Alyxia ruscifolia and and

Alyxia sharpei and and


(Acrotriche aggregata and

Acrotriche patula and

(Androstoma verticillatum leaves probably not spinescent but described by Kirkpatrick (1997) as having a 'strong, sharp point'

(Astroloma humifusum

(Astroloma conostephioides

Leptecophylla abietina and

Leptecophylla divaricata and and

Leptecophylla juniperina and and and

Leptecophylla oxycedrus and and and and

Leptecophylla parvifolia and and and and and and

Leptecophylla pendulosa and

Leptecophylla pogonocalyx and and and and

Leucopogon fraseri

Leucopogon juniperinus and and

(Leucopogon parviflorus fruits too small and dull-hued and

Leucopogon trichostylus and and and

(Lissanthe sapida leaves probably do not qualify as spinescent and and and and

Lissanthe strigosa and

(Monotoca billawinica spinescence of leaves needs confirmation

Monotoca elliptica and

Monotoca glauca leaves spinescent but fruit may remain greenish when ripe

Monotoca oreophila leaves possibly spinescent and

Monotoca scoparia and

Styphelia sieberi

(Styphelia triflora and

(Styphelia tubiflora and and and and


Podocarpus spinulosus


Persoonia juniperina

Publicado el febrero 18, 2022 12:10 MAÑANA por milewski milewski | 3 comentarios | Deja un comentario

19 de febrero de 2022

Plasticfruits, part 2: Polygalaceae

@tonyrebelo @jeremygilmore @ludwig_muller @botaneek @sandraf @benjamin_walton @felix_riegel @jan-hendrik @cpvoget @adriaan_grobler @gigilaidler @graham_g @yvettevanwijk1941 @chris_whitehouse @charles_stirton @seanprivett

...continued from

In part 1, I described how evolutionarily plastic the fruits are in a mainly southern African genus (Osteospermum) of daisies (Asteraceae).

(Also, please see

The genus Muraltia (Polygalaceae) is geographically and ecologically similar to Osteospermum, despite belonging to an unrelated family (

Like Osteospermum, Muraltia ( and and and contains wind-dispersed, ant-dispersed ( and and vertebrate-dispersed species.

Although in both genera the seeds have food-bodies attached to them to attract ants, these take different forms.

In Osteospermum the food-body is the mesocarp that envelops the seed. By contrast, in Muraltia it is a handle-like edible attachment called an elaiosome ( and

The bright-hued fleshy fruits of Muraltia spinosa and Muraltia scoparia seem adapted for dispersal and sowing mainly by tortoises such as Chersina angulata ( Unlike those of Osteospermum moniliferum, they remain crisp when ripe, and tend to fall to the ground.

Muraltia spinosa

Muraltia scoparia

In the case of both Muraltia and Osteospermum, the species dispersed and sown by vertebrates were, for several decades, classified as separate genera, based on the form of the fruits ( This has since been corrected, with the taxonomic realisation that fruits are too adaptable to be reliable indicators of phylogenetic affinity.

Muraltia spinosa ( is ecologically unusual, within the context of the Cape Floristic Region ( and the Fynbos biome (

(Also see

This is because M. spinosa shows an odd combination of

  • succeeding in at least four different situations, viz. certain forms of renosterveld (on clay-rich soils on both shale and dolerite), marginally on certain forms of nama karoo (on dolerite), certain forms of fynbos (on coarse, deep sand), and certain forms of strandveld (on calcareous coastal sand),
  • aphyllousness and retention of leaves,
  • sclerophylly (in the form of photosynthetic stems) and fleshy fruits,
  • semi-spinescence (in the form of the same photosynthetic stems) and tolerance of nutrient-poor soils with more-or-less flammable vegetation,
  • semi-spinescence and evergreenness,
  • succulent fruits and some tolerance to wildfire, and
  • endozoochory and reptilian (rather than avian) agents of dispersal and sowing.

to be continued in

Publicado el febrero 19, 2022 02:09 MAÑANA por milewski milewski | 9 comentarios | Deja un comentario

20 de febrero de 2022