Proteas with fleshy fruits: a glimpse at the time of dinosaurs?
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Proteaceae are so ancient that they coexisted with 'dinosaurs' for at least 25 million years (e.g. see https://cdnsciencepub.com/doi/10.1139/b91-116). 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 (https://www.gov.za/about-sa/national-symbols/national-flower#:~:text=The%20giant%20or%20king%20protea,cynara%27%20(the%20artichoke).) and the Cape Floristic Region (https://en.wikipedia.org/wiki/Cape_Floristic_Region) is renowned for several genera of subfamily Proteoideae, there is no species of protea with fleshy fruits (see https://en.wikipedia.org/wiki/Brabejum).
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:
- a member of subfamily Proteoideae in Tasmania (https://en.wikipedia.org/wiki/Cenarrhenes), and
- trees in the forests of China (certain species of Helicia, https://en.wikipedia.org/wiki/Helicia).
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 https://en.wikipedia.org/wiki/Persoonia_chamaepitys) 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, https://en.wikipedia.org/wiki/Emu) and cassowaries (Casuarius spp., https://en.wikipedia.org/wiki/Cassowary).
However, marsupials (https://www.cambridge.org/core/journals/journal-of-tropical-ecology/article/abs/seed-dispersal-by-kangaroos-and-their-relatives/B29C68C1FAE97F9FFB2BBB31A7C81DFD and https://www.environment.nsw.gov.au/resources/nature/PpaucifloraEia1200.pdf), certain large passerine birds (https://en.wikipedia.org/wiki/Currawong) and large skinks (e.g. https://www.shutterstock.com/nb/image-photo/eastern-shingleback-tiliqua-rugosa-threatening-open-1655139262 and https://adc.library.usyd.edu.au/view?docId=shesyst/xml-main-texts/shesystv3.xml;database=;collection=;brand=default;;query=tiliqua) also participate in the case of Persoonia (https://kids.kiddle.co/Geebungs).
Only one species of protea with fleshy fruits remains in South America (https://www.inaturalist.org/observations/38519071), 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 (https://eol.org/pages/5510758) 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 (https://en.wikipedia.org/wiki/Toronia). Here the likely agents were extinct moa (https://en.wikipedia.org/wiki/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 https://bsapubs.onlinelibrary.wiley.com/doi/pdf/10.3732/ajb.0700006.)
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 https://api.research-repository.uwa.edu.au/ws/portalfiles/portal/10036971/THESIS_DOCTOR_OF_PHILOSOPHY_CHIA_Kerryn_Anne_2016.pdf and https://www.anbg.gov.au/gnp/interns-2009/persoonia-pinifolia.html). Nonetheless, certain species of Persoonia regenerate only germinatively (see section 6.4 in https://www.awe.gov.au/environment/biodiversity/threatened/recovery-plans/persoonia-mollis-subspecies-maxima-2000).
The following compendium of illustrations is arranged in alphabetical order by genus and species. In addition Garnieria spathulifolia (https://en.wikipedia.org/wiki/Garnieria#:~:text=From%20Wikipedia%2C%20the%20free%20encyclopedia%20Garnieria%20is%20a,at%20Prony%20Bay%20in%201868%E2%80%931870%20by%20Benjamin%20Balansa.), some species of Heliciopsis (see https://floraoftheworld.org/taxon/flora/17592186252329) and Bleasdalea may qualify.
Acidonia microcarpa: no photos available
https://florabase.dpaw.wa.gov.au/browse/profile/21315
https://www.inaturalist.org/taxa/472875-Acidonia-microcarpa
Athertonia diversifolia
https://www.inaturalist.org/taxa/528901-Athertonia-diversifolia
https://www.inaturalist.org/observations/104746276
Bellendena montana: no photos of fruits available despite the many photos of flowers
https://www.inaturalist.org/taxa/323299-Bellendena-montana
Catalepidia heyana
https://www.inaturalist.org/taxa/1028637-Catalepidia-heyana
https://apps.lucidcentral.org/rainforest/text/entities/catalepidia_heyana.htm
https://www.bing.com/images/search?view=detailV2&ccid=YKmZ3Nt3&id=C14E674227AF6F66E403C5A9D53C2AB6F995FAB5&thid=OIP.YKmZ3Nt3sw4RBLIdimiAuAHaLH&mediaurl=https%3a%2f%2fth.bing.com%2fth%2fid%2fR.60a999dcdb77b30e1104b21d8a6880b8%3frik%3dtfqV%252bbYqPNWpxQ%26riu%3dhttp%253a%252f%252fwww.anbg.gov.au%252fcpbr%252fcd-keys%252fRFK7%252fkey%252fRFK7%252fMedia%252fImages%252fentities%252fCatalepidia_heyana%252fP070029_BG1244.jpg%26ehk%3dUz%252f47eoKnh1se%252bKqE7en8xvF3AsKVU%252fe8cnzGl%252f74Kk%253d%26risl%3d%26pid%3dImgRaw%26r%3d0&exph=900&expw=600&q=catalepidia+fruits&simid=607995600704588530&FORM=IRPRST&ck=7D8CC8FED36CC2C7535BD4B4F3B5C13C&selectedIndex=1&ajaxhist=0&ajaxserp=0
Cenarrhenes nitida
https://www.inaturalist.org/taxa/323298-Cenarrhenes-nitida
https://www.inaturalist.org/observations/106057578
https://www.inaturalist.org/observations/82760740
https://www.inaturalist.org/observations/77864388
https://www.inaturalist.org/observations/61845410
Gevuina avellana
https://www.inaturalist.org/taxa/490916-Gevuina-avellana
https://zoom50.wordpress.com/2012/01/18/avellano-chileno-chilean-hazel-gevuina-avellana-2/
https://www.inaturalist.org/observations/105673434
https://www.inaturalist.org/observations/101433012
https://www.inaturalist.org/observations/86360387
https://www.inaturalist.org/observations/83827066
https://www.inaturalist.org/observations/71179681
https://www.inaturalist.org/observations/70339280
https://www.inaturalist.org/observations/22422268
https://upload.wikimedia.org/wikipedia/commons/3/30/Avellano_%28Gevuina_avellana%29_leaves_%26_seeds_%28Inao_V%C3%A1squez%29_001.jpg
https://www.rarepalmseeds.com/gevuina-avellana
https://www.pinterest.com.au/amp/pin/412712753351801260/
https://www.alamy.com/chilean-hazelnut-or-avellano-gevuina-avellana-proteaceae-native-to-chile-edible-flowers-and-fruit-chiloe-national-park-cucao-chiloe-island-x-region-of-the-lakes-chile-image226042995.html
Helicia: this genus includes species with fleshy fruits and species in which the fruits ripen dry and brown.
Helicia australasica
https://www.inaturalist.org/taxa/186567-Helicia-australasica
https://www.flickr.com/photos/s_glenum/4434561695
https://www.inaturalist.org/observations/93967175
https://www.territorynativeplants.com.au/helicia-australasica-creek-silky-oak
https://www.flickr.com/photos/xylopia/11621919413
https://landforwildlifetopend.com/2016/05/04/wildflowers-walk-and-macropod-talk/helicia-australasica-2-medium/
Helicia cochinchinensis
https://www.inaturalist.org/taxa/774568-Helicia-cochinchinensis
https://www.inaturalist.org/observations/67996194
Helicia glabrifolia
https://www.inaturalist.org/taxa/370461-Helicia-glabriflora
https://www.inaturalist.org/observations/91702093
https://www.inaturalist.org/observations/63742459
Helicia nortoniana
https://www.inaturalist.org/taxa/919882-Helicia-nortoniana
https://www.inaturalist.org/observations/97622002
https://www.inaturalist.org/observations/104550345
Hicksbeachia pinnatifolia
https://www.inaturalist.org/taxa/538045-Hicksbeachia-pinnatifolia
https://twitter.com/texaninoz/status/1215741634190565377
https://www.inaturalist.org/observations/54377000
https://www.facebook.com/808212652542511/photos/last-year-i-identified-red-bopple-nut-hicksbeachia-pinnatifolia-as-a-host-specie/2579320188765073/
https://www.flickr.com/photos/17674930@N07/50049018293
https://alchetron.com/Hicksbeachia
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.
https://www.inaturalist.org/observations/102047105
https://www.inaturalist.org/observations/72350903
https://www.inaturalist.org/observations/71928145
https://www.inaturalist.org/observations/67545037
Persoonia falcata
https://www.inaturalist.org/taxa/764693-Persoonia-falcata
https://skipas.wordpress.com/native-plants/plant-families-n-p/proteaceae/persoonia-falcata-wild-pear-or-geebung/
https://www.inaturalist.org/observations/67402259
Persoonia gunnii
https://www.inaturalist.org/taxa/323319-Persoonia-gunnii
https://www.inaturalist.org/observations/104860284
https://www.inaturalist.org/observations/76512999
https://www.inaturalist.org/observations/70790819
https://www.inaturalist.org/observations/38821076
https://www.inaturalist.org/observations/21904761
https://www.inaturalist.org/observations/13510689
Persoonia juniperina
https://www.inaturalist.org/taxa/323847-Persoonia-juniperina
https://www.inaturalist.org/observations/99970446
https://www.inaturalist.org/observations/103673975
https://www.inaturalist.org/observations/95526358
https://www.inaturalist.org/observations/86932752
Persoonia lanceolata
https://www.inaturalist.org/taxa/321208-Persoonia-lanceolata
https://www.inaturalist.org/observations/99856576
https://www.inaturalist.org/observations/61902946
Persoonia linearis (seed mass about 1.9 grams)
https://bushcraftoz.com/threads/persoonia-linearis-narrow-leaved-geebung.1194/
https://www.inaturalist.org/taxa/321204-Persoonia-linearis
https://www.inaturalist.org/observations/84806108
https://www.inaturalist.org/observations/100666655
https://www.inaturalist.org/observations/99597875
https://www.inaturalist.org/observations/87831952
https://www.inaturalist.org/observations/79206640
Persoonia mollis
https://www.awe.gov.au/environment/biodiversity/threatened/recovery-plans/persoonia-mollis-subspecies-maxima-2000
https://resources.austplants.com.au/plant/persoonia-mollis/
https://www.inaturalist.org/taxa/926982-Persoonia-mollis
https://www.inaturalist.org/observations/100669928
https://www.inaturalist.org/observations/82304327
Persoonia muelleri
https://www.inaturalist.org/taxa/883707-Persoonia-muelleri
Persoonia pinifolia
https://www.inaturalist.org/taxa/320841-Persoonia-pinifolia
https://www.inaturalist.org/observations/94206824
https://www.inaturalist.org/observations/84654705
https://www.inaturalist.org/observations/1387705
https://www.inaturalist.org/observations/61453426
https://www.inaturalist.org/observations/93010856
https://www.inaturalist.org/observations/99168142
https://www.inaturalist.org/observations/97724337
https://www.inaturalist.org/observations/97232663
https://www.inaturalist.org/observations/95649789
https://www.inaturalist.org/observations/90745398
https://www.inaturalist.org/observations/89973222
https://www.inaturalist.org/observations/82836948
https://www.inaturalist.org/observations/65563601
https://www.inaturalist.org/observations/59774011
Persoonia silvatica: Floyd (1989) states on page 296: "Drupe, purplish lemon-green...15-18 mm diameter. Flesh edible, mucilaginous and fibrous, tasting like passionfruit."
https://www.inaturalist.org/taxa/1032909-Persoonia-silvatica
Persoonia virgata
https://www.fraserisland.net/fraser-island/fraser-island-plant/bush-tucker
https://www.inaturalist.org/taxa/554191-Persoonia-virgata
https://www.inaturalist.org/observations/95805824
Sleumerodendron: no photos available
Toronia toru
https://www.inaturalist.org/taxa/406557-Toronia-toru
https://www.nzplants.auckland.ac.nz/en/about/seed-plants-flowering/proteaceae/toronia-toru.html
https://www.inaturalist.org/observations/2849986
Triunia youngiana
https://www.inaturalist.org/taxa/554194-Triunia-youngiana
https://www.inaturalist.org/observations/82829422
https://www.inaturalist.org/observations/48398475
https://www.inaturalist.org/observations/46458697
Turrillia: no photos available
Virotia: no photos available