This image of a female Bengal tiger (Panthera tigris tigris) in Kanha National Park (India) by Charles J Sharp is shared under the Creative Commons Attribution-Share Alike 4.0 International license. [to discover why this plant item has a tiger, you’ll need to read to the end of the piece…]
No doubt 2024 will bring its share of new* plant species. But, now that 2023 is behind us, what botanical novelties* did that year give the world? Time for a phytological retrospective.
For a Kew-centric view of things, Martin Cheek’s post showcases the ‘top 10 plants’ named by workers at that august site of plant and fungal research. And why not? After all, “In 2023, 74 plants and 15 fungi were named by botanists and mycologists here at Kew and at our partner organisations around the globe”. That listing includes, “The orchid saved by a bird – Aeranthes bigibbum”, “Underground trees of Angola – Baphia arenicola and Cochlospermum adjanyae”, “An orchid living atop a volcano – Dendrobium azureum”, and “The fungi that live in Antarctica – Arthonia olechiana, Sphaeropezia neuropogonis”. I don’t propose to repeat all of that news item here. But, I do want to say a little bit by way of additional information about two of them [because I had plans to anyway, before the Kew item was posted and known to me…]. Not only are these plants new to science, unusual aspects of their biology encourage us to reconsider what we actually know about plants.
Is meat on the menu, or not..?
Our first plant is one that make us think about what plants do to supplement their nutrition, as indicated by the Kew list’s intriguingly-worded heading, “A new carnivorous plant… or not? – Crepidorhopalon droseroides”**. With the exception of such ‘flexitrophic’ plant species as Triphyophyllum peltatum – in which the carnivorous condition is turned on/off by phosphorus availability [see more here] – when it comes to plants and carnivory (DK Berard; Barry Rice), one might suppose that plants either are, or are not carnivorous. Wouldn’t it be nice if nature was so cut-and-dried and clear? Spoiler alert: It’s not(!)
There are plants whose carnivorous nature is suspected, but has yet to be confirmed. Such plants have been called ‘protocarnivores’ (Mark Chase et al., Botanical Journal of the Linnean Society 161: 329–356, 2009; https://doi.org/10.1111/j.1095-8339.2009.01014.x), or ‘murderous plants’. But, since we can’t say that “evolution is moving in some particular direction” (Barry Rice), the word ‘proto-carnivorous’ should be avoided. Respecting that eminently sensible viewpoint, and noting that “plants that have some, but not all, of the above attributes [of true carnivorous plants] are called semi-carnivorous, para-carnivorous, or sub-carnivorous” (Barry Rice), I shall call them para-carnivores.
Although para-carnivorous plants have some of the characteristics of other genuine, bona-fide, carnivorous plants, they don’t have enough to confirm their carnivorous nature ***. For example, the putative carnivore may have structures that trap insects, but there is as yet no evidence that such creatures are used as a nutrient source by the plant. That is the situation with Crepidorhopalon droseroides (Eberhard Fischer et al., Phytotaxa 603: 191-198, 2023; doi: https://doi.org/10.11646/phytotaxa.603.2.6)****.
Certainly, the plant’s potentially carnivorous nature was clearly in the minds of those who first-described it because their article is entitled “A new and possibly carnivorous species of Crepidorhopalon (Linderniaceae) from Mozambique”. And evidence to support that view is provided by their Figure 2, which shows images of insects – and even a spider – sticking to the plant’s viscid glands. However, although the paper’s abstract tells us that “The hypothesis that the species may be carnivorous is discussed” (Eberhard et al., 2023), that is all that can be done at this stage. Images of invertebrates trapped on the sticky glands aren’t enough to prove plant carnivory. It may be that insects become trapped by the plant’s sticky hairs because they are primarily a defence against herbivory, rather than a means to capture food (which method is used by carnivorous plants such as the sundews (Drosera species) (Melisa Pettruzello)). If products of decay and decomposition of dead insect are absorbed by the plant and used in its growth, then that’s an added bonus from the structure’s primary purpose; it doesn’t constitute true carnivory. If, however, the host plant were to secrete digestive enzymes and absorb the products of such biochemical breakdown, then that looks like carnivory.
Clearly, more work is needed to find out if Crepidorhopalon droseroides is a genuine carnivorous plant, as Eberhard et al. acknowledge in concluding “field and laboratory studies of living plants are required to test our hypothesis that this species is carnivorous”. With that in mind, it will be interesting to see who responds to Scott Zona’s ‘X-rated’ plea: “Somebody has got to study this thing & find out whether it’s carnivorous”. But, whether carnivorous or not, discovery of such a species underlines the point that there’s still a lot to learn about plants – which is one of the reasons why they are so fascinating!
Turning flower biology upside-down…
This bizarre story – about a palm with remarkable reproductive biology***** – challenges our understanding about how plants ‘work’. For instance, we might assume that flowers are supposed to be raised skywards upon stems so they can be seen by pollinating animals [zoophily] or where they can be buffeted by a breeze for those plants that are wind-pollinated [anemophily]. That this is not always the case is seen in this story’s sub-heading from the ‘Kew list’, “The palm that flowers underground – Pinanga subterranea”.
This new species* was formally described by Agusti Randi et al. (PALMS****** 67(2): 57–63, 2023). ‘Discovered’* in Borneo, it’s unusual floral biology was admirably summarised thus, “This remarkable new species is the first palm described as flowering and fruiting underground”. The full article will provide those interested with more information, but that’s the important ‘take-home message’*******.
Appropriately, this species was featured in the ‘Flora obscura’ section of Plants People Planet by Benedikt Kuhnhäuser et al. (Plants, People, Planet 5:815-820, 2023; https://doi.org/10.1002/ppp3.10393). Usefully, that article points out that, although rare, the phenomena of geoflory and geocarpy (production of flowers and fruit below ground, respectively) [for more on those phenomena, see William J Baker], are found in 33 angiosperm families, but Pinanga subterranea is the first member of the palm family known to do both.
As you might expect from such a story, it was widely covered in the non-specialist media outlets such as Sebastian Kettley & Ben Evans’ news item on the Kew site, Graeme Green’s article in the UK’s Guardian newspaper’s Environment section, and PhysOrg, a site dedicated to news about science for science-minded people. Written in ways that are designed to be widely-understood, those items are intended for a non-specialist audience – i.e. the general public, this sort of publicity can only help to raise awareness amongst the public of the fascinating world of plants and their biology.
It should be borne in mind that, although stories of ‘plants behaving oddly’ are eye-catching, and therefore deemed ‘newsworthy’, all plants are worth writing and talking about. However, that’s not necessarily being done. If it was, there would be greater appreciation of the value of plants by the general public – i.e. much less ‘plant blindness’. Plant blindness – or rather, combating it – is still a major concern among all those who write about plants in the hope of educating others about the importance of these organisms. At plantcuttings.uk we’ll continue to do that. But we’ll also be grateful for the weird, wonderful, and remarkable plant stories that get picked up by the more mainstream media – with their much larger audiences – that help to further the cause of eradicating plant blindness, and enhancing the public’s botanical literacy. So, here’s to weird and wonderful [and it being widely-reported]!
Finally, and by way of insight into what 2024 brings regarding new plant species, I mention Polygonum chaturbhujanum (Chandramohan Kolagani et al., Annales Botanici Fennici 61(1): 25-28, 2024; https://doi.org/10.5735/085.061.0104). I know little about the story because I’ve not managed to get hold of the full article. But, what I do know, and which is probably the most interesting thing that anybody needs to know, is that the plant was discovered in a tiger reserve. If that’s sounds incredible, it’s true, as evidenced by the title of the scientific paper that describes it, “Polygonum chaturbhujanum (Polygonaceae), a New Species from Pench Tiger Reserve, Maharashtra, India”. So, whatever the plant discoveries of the new year bring, they’ll have to go quite some way to best this one(!)********. Plant-hunting in a tiger reserve!?! Now, that’s hard-core field botany! [Yes, Mr P Cuttings does note that he’s managed to start and finish this piece with items about ‘plants and carnivores’…].
* NB, whilst these plants are ‘new’ in the sense of new to science [i.e. have not previously been given a proper scientific name and formally described], they are not new to nature. And they’re not necessarily new to humanity – i.e. they’re not a new discovery – because peoples of the regions where the ‘new’ plants were found may have known about them – and even used them – for centuries. For example, the ‘underground palm’ in the second story above has many vernacular names (DM Gutierrez; Joely Taylor) amongst the locals: “Pinang Tanah (Malay, West Kalimantan). Pinang Pipit, Muring Pelandok (Kendorih language, Central Kalimantan). Tudong Pelandok (Iban language, Sarawak)” (Randi et al., 2023). For a plant to have (m)any ‘common names’ indicates that it was widely known about, and long before the scientists entered the picture, and ‘discovered’ it. Relatedly, one might reasonably presume that a plant with local names indicates that it is a species with some relevance to the lives of the people. In the case of the palm it appears to be a nutritional one – in Central Kalimantan (Indonesia), the ripe fruit flesh “is often eaten raw; it has a soft and juicy texture and a predominantly sweet taste” (Randi et al., 2023). Indeed, the fruits are actively sought after as a forest snack by people in that region (Kuhnhäuser et al. 2023). It’s certainly not ‘new’ to people, just scientists(!)
A report of a newly-described plant species is one – of the few – instances where use of the word ‘new’ is justified in a scientific paper, or a news item about such a discovery. For some commentary about use of words such as ‘new’, and ‘novel, see Howard Bauchner (JAMA Netw Open. 2023;6(12):e2349125. doi:10.1001/jamanetworkopen.2023.49125), and here.
** This species is so newly-described that it is not yet shown as an accepted species in Kew-hosted Plants Of the World Online [when accessed on 17th January, 2024], nor on Wikipedia [when accessed on 17th January, 2024]. Although Crepidorhopalon droseroides appears on World Flora Online, “This name is currently unchecked and awaiting taxonomic scrutiny” [accessed on 18th January, 2024]. Crepidorhopalon droseroides does, however, appear in the Flora of Mozambique, with pictures.
*** According to the International Carnivorous Plant Society, carnivorous plants are “predatory flowering plants that kill animals in order to derive nutrition from their bodies. They share three attributes that operate together and separate them from other plants: they, 1, Capture and kill prey, 2 Have a mechanism to facilitate digestion of the prey, and 3 Derive a significant benefit from nutrients assimilated from the prey”. Those criteria are elaborated upon by Barry Rice at his carnivorous plants FAQ site: A plant is carnivorous if it has the following three attributes: 1, The plant must have clear adaptations to capture prey such as a trap. It can have extra features that help improve the trapping efficiency; 2, The plant has some way to digest the prey into a form that can be absorbed by the plant. The plant may produce digestive enzymes, or it may rely on bacteria or other organisms to perform the digestion for it; and 3, The plant must have a way of absorbing the nutrients, and must benefit from the nutrients.
For completeness, that list of three has been further expanded to a set of five by Aaron Ellison & Lubomir Adamec (2018) [“Introduction: What is a carnivorous plant?”, p. 4. In: Carnivorous Plants: Physiology, Ecology, and Evolution (First ed.). Oxford University Press], quoted accurately here, plants are considered carnivorous if they have these five traits: 1, capture prey in traps; 2, kill the captured prey; 3, digest the captured prey; 4, absorb nutrients from the killed and digested prey; 5, use those nutrients to grow and develop. And, other traits may include the attraction and retention of prey.
**** I thank Prof Dr Eberhard Fischer (Koblenz University, Germany) and Dr Iain Darbyshire (of RGB Kew, UK) who kindly supplied copies of their Crepidorhopalon droseroides article so I had the benefit of reading the paper in its entirety in writing this blog post.
***** The palm family is a great source of strange biological behaviours. One of the strangest is the notion of palms that ‘walk’ (Carly Cassella). For more on that story, see Laura Doughty, here, here, here, here, and Benjamin Radford.
****** PALMS, the journal of the International Palm Society, is “an illustrated, peer-review quarterly devoted to information about palms” [It’s always nice to see a scientific publication that ‘does what it says on the tin’.]
******* Although not really a take-home message of general interest, the other biological fact about this plant that caught my eye was the statement that, “Having observed populations of P. subterranean in the wild, we now understand why the stem, crownshaft and inflorescence are underground. Excavated plants show “saxophone growth” (Tomlinson 1990)” (Randi et al., 2023). I’d never heard of saxophone growth before [and suspect I won’t again…]. For more on this phenomenon more generally, see Bob Harms, David George Haskell, here, and Joyce Nascimento e Souza et al. (Annals of Botany 119: 353–365, 2017; https://doi.org/10.1093/aob/mcw215).
For more on the specifics of that particular palm, here’s what Randi et al. say “with the stem growing initially downwards to a depth of 20–30 cm and then upwards (Fig. 4). Internodes are highly condensed, so the stem remains buried entirely below the ground even in mature plants. Inflorescences are short and infrafoliar, and thus usually do not emerge above ground. In addition, organic litter accumulates around the stem by the widely spreading petioles and leaves. The litter then rots and is invaded by roots (which grow upwards into it), building up around the stem and crownshaft. Rain, which splashes sand and soil around, also plays a role. Together, these factors create the impression of the plant burying itself underground (Figs. 2 & 3)”. So, here we have a plant news item that’s about palm biology, and all that jazz (Furtados School of Music; Charles Waring)…
******** I’m really curious to know how many more new plants there might be in that tiger site. I would investigate, but I have too many … err … reservations…
Plant Cuttings 
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