Carnivorous

Carnivorous plants are the psycho killers of the plant world… kaskasé. They consume at least part of their nutrients by trapping and digesting insects or small animals using elaborate traps, tricks and sticky business.

This year I spent precious time traipsing through lush forests that make Sarawak in Malaysian Borneo, so iconic. In Bako National Park–a rugged coastal rainforest accessible only by boat–the lowland, forested valley is fringed at beachfront by dense mangroves and pandanas trees, and rises steeply inland to a high plateau mounted by clinging kerangas.

Kerangas (“land that cannot grow rice”) is a kind of tropical heath. It typically grows on acidic, sandy soils that are very poor in essential plant nutrients. Since deporporate soils favour organisms that can supplement this poor supply, Kerangas is ripe habitat for carnivorous plants. 

Bako is famous for its’ teaming wildlife. Troops of Proboscis monkeys are easily spotted lounging in the treetops and charismatic Bearded Bornean Pigs range across the forest floor. But Bako is equally spectacular for the range of vegetation represented there, and the diversity of plants within each.

Of all the trails stretching out from Park Headquarters, the Lintang trail is an unparalleled botanists delight. Herein find the carnivorous beasts of Bako.

 

Pitcher plants

Pitchers are specially-adapted leaves that use tricks and traps to catch and digest insects or small animals. Feed the beast.

Nepenthes gracilis 

Smooth-walled, modest beasties, N. gracilis wraps its way around branches and climbs high, ladening trees and shrubs with immoderate aerial pitchers. Below these towering masses of wrapping vine, the ground-dwelling lower pitchers are found in camouflaged clusters, nestling amongst dry leaves that have been cast off by the host tree overhead.

 


Nepenthes rafflesiana

Deceptively handsome, both ground and aerial pitchers of N. rafflesiana are striking for their size, monstrous patterning and shiny, striped peristomes (the botanical term for the rim around the opening of the pitcher). Most seductive are the flesh-pink lower pitchers that sport hairy, widely-flanked wings. “Come in,” they taunt precociously.

 


Nepenthes ampullaria

Found nestled on well-shaded patches of the forest floor amongst dingy, soggy leaf debris, these pot-shaped shorties appear to cuddle in somewhat less-than-ominous clusters. Although their aerial pitchers are very few and far between, N. ampullaria are by no means downtrodden. With thin lids flung wide open and curt wings leading to a smooth, skirting peristome… tread carefully.

 


Nepenthes albomarginata

Whether aerial or on the ground, pitchers of N. albomarginata are unmistakable. Each one of these sleek killing machines is rimmed with a distinctive white band below the peristome–that mimics a halo. Images can be deceiving. 

 


Sundew

High on the Bako plateau along muddy, sunburnt creek banks, the stellate whorls of a sundew are easily stepped on or over. Measuring less than 3 cm in diameter, use the sunlight as your guide. Sundews sticky deathtrap droplets glisten in the light, giving rise to their common name and giving them away to the eager human eye.

Drosera spathulata

The spatula-shaped leaves of this sundew species (hence the name D. spathulata) are covered with tiny hairs, each dripping with sticky fluid that is secreted by the plant. Once a crawling victim becomes trapped in this gloopy goop, the tentacular hairs of a sundew bend over to enmesh it’s prey. Trapped in this hairy grave, the insect is dissolved for digestion by this beastly little plant.

 


Bladderwort

The leaves of this inconspicuous hunter live beneath the soil–out of sight–where they have adapted to support bladder-like insect traps that suck in prey at a tremendous speed. Microscopic animals that enter… cannot leave. 

Utricularia racemosa 

They appear as a delicate, slender stalk–no taller than a few centimetres–mounted by a single, modest flower. The flowers of U. racemosa are a soft blue-violet, aptly compensating for the terror waiting below ground. U. nummularia can also be found in Bako, sporting flowers in bright yellow (but they did not grace me with their presence on this visit). 

 

Fungus suckers

The plant family Burmanniaceae is a long-standing botanical heartthrob (#Botanicalheartthrob) of mine. Ghost-like obligate parasites, bound by their evolutionary heritage to a strange existence amongst the fallen debris that litters a forest floor, the Burmaniaceae feed on fungus.

 

 

The condition of this odd plant variety is called mycoheterotrophism. It’s a parasitic relationship between certain plants and fungi, where the plant derives some, if not all, of it’s food by parasitising the fungus.

That’s right. Instead of feeding on sunlight like good old regular plants, mycoheterotrophs feed on fungus. Cheaters.

Amazingly, many of the Burmanniaceae have completely lost their ability to photosynthesise. They are achlorophyllous (pronounced ‘ay-cloro-fi-lus’), meaning they have no chlorophyll; the cellular centres for converting harvested sunlight into sugars that feed the plant.

No chlorophyll at all folks. That’s like being an animal without a stomach. Oh wait…

 

 

The habit of plants deriving nutrition from fungus has evolved several times independently, including in both monocots and eudicots, and is most prolifically represented in each clade amongst the Orchidaceae (orchids) and Ericaceae (e.g. Epacris impressa, the stunning floral emblem of Victoria). Similarly, it is likely that the extreme, obligate fungus-sucking habit–necessitated by a complete evolutionary loss of chlorophyll–has arisen several times independently within the Burmanniaceae family alone (Merckx et al. 2008). Burmanniaceae’s mycoheterotrophism is, therefore, considered an adaptation to deal with dank, dark, low light conditions that persist on the forest floor (Bidartondo et al. 2004).

Unaware of this diversity, and being the first fungus-sucking plants I had encountered, Burmaniaceae instantly captured my imagination. Too many zombie films, perhaps, but also a novel insight into the oddities of natural selection.

 

 

There is considerable conflicting information available on the number of genera and species within the family Burmanniaceae. Listings range from between seven and seventeen genera, and 95 to 159 species (see also Merckx et al. 2006). It is unclear whether this issue is due to conflicting opinions on synonymous species (where some botanists believe two differently named species constitute one and the same), synonymy of the families Burmanniaceae and Thismiaceae, or outdated information on a number of online databases and in the literature.

“…eking out what appears a rather diminished and utterly fragile existence for a traditionally photosynethic organism…”

According to the APG IV system (Angiosperm Phylogeny Group: APG IV 2016), a modern, mostly molecular-based system of classifying flowering plants, there are eight genera in the Burmanniaceae family, comprising some 96 species of fungus-sucking plants.

The biggest of these genera, Burmannia, includes roughly two thirds of these species, and is spread across tropical and subtropical parts of Africa, Oceania and the Western Hemisphere. The next largest genus is Gymnosiphon, comprising 24 species across the Old and New World tropics, but the remaining genera are far less speciated; Apteria (3 species, tropical and subtropical America), Dictyostega (1 species, Mexico and Brazil), Marthella (1 species, Trinidad), and four genera native to tropical S. America, including Campylosiphon (1 species), Cymbocarpa (2 species), Hexapterella (2 species) and Miersiella (1 species).

 

 

In Australia, Burmanniaceae is represented by just two native speciesBurmannia juncea (above left), native to Northern Australia (swampy areas, streamsides and wetlands), and Burmannia disticha, native to the east coast of NSW and QLD (swamps and wetlands in coastal regions). According to the Atlas of Living Australia, a community science database on the continent’s flora and fauna, the southeast Asian B. coelestis (Zhang & Saunders 2000) also occurs across far northern Australia.

Despite eking out what appears a rather diminished and utterly fragile existence for a traditionally photosynethic organism, these little creeps, at least in Australia, are considered not threatened and of least conservation concern.

Good job zombie herbs. Keep on keeping on.

 

References

Online references are linked to via in-text hyperlinks.

APG IV (2016) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society 181 (1): 1–20. doi:10.1111/boj.12385.

Bidartondo M. I., Burghardt B., Gebauer G., Bruns T. D. & Read D. J. (2004) Changing partners in the dark: isotopic and molecular evidence of ectomycorrhizal liaisons between forest orchids and trees. Proceedings of the Royal Society of London B 271: 1799–1806.

Merckx V., Chatrou L., Lemaire B., Sainge M., Huysmans S. & Smets E. (2008) Diversification of myco-heterotrophic angio- sperms: evidence from Burmanniaceae. BMC Evolutionary Biology 8: 178.

Merckx V., Schols P., Kamer H. M.-V. D., Maas P., Huysmans S. & Smets E. (2006) Phylogeny and evolution of Burmanniaceae (Dioscoreales) based on nuclear and mitochondrial data. American Journal of Botany 93: 1684–1698.

Morton, J.B., Walker, C. (1984) Glomus diaphanum: A new species in the Endogonaceae common in West Virginia. Mycotaxon 21: 431-440.Zhang D. & Saunders R. M. K. (2000) Systematics of the Burmannia coelestis complex (Burmanniaceae). Nordic Journal of Botany 20: 385–394.

Images are presented unaltered from the original source and were: freely available under creative commons, or; were free for non-commercial sharing with appropriate attribution given (e.g. see here, but links to the originals are provided in each case, wherein the licensing particulars for each image can be found), or; were provided with direct permission from the author (Mac H. Alford Nodding-nixie photograph). Details of authorship can be found in each picture caption. 

Pooter power !

 

 

Extra-happy happy snaps of the fossil conservation process.

Each photograph is captioned with a brief description of the technique featured, but for a romanticised description and more detail of the ‘how’s’ and ‘why’s’ see the rockdoc article Patients.

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