| Boquila | |
|---|---|
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Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Ranunculales |
| Family: | Lardizabalaceae |
| Genus: | Boquila Decne. |
| Species: | B. trifoliolata |
| Binomial name | |
| Boquila trifoliolata | |
| Synonyms[1] | |
| |
Boquila is agenus offlowering plants in thefamilyLardizabalaceae,endemic to temperate forests of central and southern Chile and Argentina. It ismonotypic, being represented by the single speciesBoquila trifoliolata, locally known asvoqui blanco orpilpil in its native range,[2] and sometimes referred as thechameleon vine since a recent report on leaf mimicry. The species was first described in 1782 byJuan Ignacio Molina, and the genus itself was established in 1839 byJoseph Decaisne.B. trifoliata forms non-parasiticvines that wind around host plants, using them for structure and protection.B. trifoliata ismonoecious, and its flowers are an off white color. It bears an edible fruit and has been historically used in rope and basket making.
B. trifoliata is the only known plant species reported to engage in mimetic polymorphism, or the ability to mimic multiplehost species, often simultaneously. This is a form ofBatesian mimicry, when a harmless species mimics a harmful one to ward off predators. Contact between the vines and host trees was reported not to be necessary for mimicking to commence. However, after a decade of the original study describing the species mimicry capabilities in 2014, no independent research groups have verified the field observations and the mechanism by which this mimicry would occur is still unknown. Hypotheses about the mimicry mechanism include microbial mediatedhorizontal gene transfer,volatile organic compound sensing, and the use ofeye-like structures.
Boquila is amonotypicgenus offlowering plants (angiosperms) in the familyLardizabalaceae with one known species,Boquila trifoliolata.[3][4] The species was first described asDolichosfunarius in 1782 byJuan Ignacio Molina, and in 1817, theholotypeLardizabalatrifoliolata was named byAugustin Pyramus de Candolle.[5][6] In 1838,Stephan Endlicher,Eduard Friedrich Poeppig, andGustav Kunze proposed the nameLardizabaladiscolor. In between 1837 and 1839,Joseph Decaisne identifiedBoquilatrifoliolata andBoquiladiscolor, and established theBoquila genus in 1837.[7] The nameBoquiladiscolor was later declared aorthographic variant. In 1936,Gualterio Looser attempted to reclassify the species toLardizabalafunaria based upon the observations ofCarlo Giuseppe Bertero, but this classification is not considered valid.[8][9]
Due to itsmimicry capabilities,Boquila trifoliolata is sometimes referred to as the chameleon vine.[10][11][12]
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Boquila trifoliolata is awoody vine with a highly variable appearance due to itscrypsis abilities.[4] The vines areevergreen or partlydeciduous, meaning they largely retain their leaves over winter.[13] The vines follow a twining pattern when climbing host plants, meaning the stems bend around host plants during their ascent.[14] Thebranches are thin, less than 1 cm (0.39 in) in diameter, and are covered in red-brownbark. Thelenticels are elliptical in shape, and the wider branches are a speckled grey color.[13] When not mimicking a host plant,B. trifoliata employs smaller 'charlatan leaves' that are short, stubby, and have three lobes (trifoliate).[4] Thepetioles range from 2 cm (0.79 in) to 6 cm (2.4 in) in length and thepetiolules range from 0.5 cm (0.20 in) to 1.5 cm (0.59 in) in length.Leaflets are oval or elliptical and range from 2 cm (0.79 in) to 6 cm (2.4 in) in height and 1 cm (0.39 in) to 3 cm (1.2 in) in width. The base of the leaves is rounded, the margins are irregular (most often trilobate), the tips are rounded and wide-angled, the top of the leaves are dark green andhairless, the undersides areglaucous (pale-grey to blue-green), and theveins have apinnate pattern.[15][13]
In its natural habitat,flowering occurs between September and December, whilefruiting occurs between January and March. This pattern is opposite when the plant is raised in theNorthern Hemisphere.[13]B. trifoliata ismonoecious, meaning that both male and female floral parts are present in the same plant.[13] Thepetals are small (1.5 cm (0.59 in) to 3 cm (1.2 in) in length) and have a green-white to yellow-white color. These flowers tend to be in 2- to 4-flowerumbels with small hairs and lepidote bracts along the petals. Each flower has sixsepals, and arebiserate,petaloid, ovate, and the three inner sepals are larger than the outer ones.Staminate flowers (male flowers) have six stamens, petals in an opposite pattern, andanthers are oblate.Carpellate flowers (female flowers) have six conicalstaminodes, threecarpels, an elongatedstigma, and sutures running vertically up the petals.[15][13]
Thefruits are small, ranging from 0.5 cm (0.20 in) to 1 cm (0.39 in) in diameter, and white. There are typically 1-4 seeds perberry, ranging from 2.5 mm (0.098 in) to 5 mm (0.20 in). Theseeds are oval, brown, and contain large amounts ofendosperm.[13] Seeds are largelydispersed via animal vectors and readilygerminate when planted.[15][16]
Boquila trifoliolata is the only plant known to engage in mimetic polymorphism, meaning it can mimic the leaves of multiple host plants.[4][17] Other species of vines are capable of limitedcrypsis for one host species, butB. trifoliata is notable since it can mimic the leaves of multiple species, with one vine capable of simultaneously mimicking multiple hosts. Mimetic polymorphism is only observed elsewhere in some species of butterflies, but that is the result ofgenetic divergence, unlikeB. trifoliata which engages in rapid changes in leaf morphology.[4]
Once the vines approach a host tree's branches, the leaves begin to change their size, shape, color, vein patterns, spines, and orientation to match the host plant; sometimes expanding to 10x their original size.[4]B. trifoliata has been observed mimicking over 20 different species of plants.[18] These include native species such asLuma apiculata,Cissus striata, andRhaphithamnus spinosus but also non-native species such asRanunculus repens.[19]
Unlike most other mimicking species, close proximity is enough to induce mimicry and contact is not required.[4] In one controversial study,B. trifoliata has been noted to mimic the leaves of plastic plants.[20] If the vines approach another tree, the vine begins simultaneously mimicking that species as well.[4] Mimicry is largely confined to the leaves closest to the host, meaning that sections of the vine approximately 60 cm (24 in) away from the host retain the non-mimickingphenotype.[19] This is a form ofBatesian mimicry, where theB. trifoliata is harmless but resembles a less palatable or harmful plant to ward offherbivory species andpests.[21][22][4]
The exact mechanism by which mimicry occurs is not well understood but may involvechemical,odor,genetic,metagenomic,transcriptomic,proteomic,metabolomic,epigenetic, and/ormicrobial cues to identify and mimic the species it is attached to.[19][4]
Plant ecologist Ernesto Gianoli proposed that the host tree may be emittingvolatile organic compounds (VOCs) into the environment thatB. trifoliata can detect.[4] The use of VOC-mediated plant-to-plant communication is widely employed in non-specific biological processes, including up-regulation of defense-related genes, and could explain why no contact is necessary for mimicry. Criticisms of this hypothesis are that this would mark the first time that VOCs were used to change plant morphology, and thatB. trifoliata's mimicry has a level of specificity that is not normally seen with VOC-mediated responses.[19]
Another hypothesis proposed by Gianoli is thatB. trifoliata's mimicry is mediated byendophytic microbes that conducthorizontal gene transfer (HGT) betweenB. trifoliata and the host plant. This would influence the genes,transposons, and/orepigenetics of the plant's leaves, identifying the host and changing the leaf's morphology without necessitating physical contact.[19][23] In a 2021 study, Gianoli found that themicrobiomes ofB. trifoliata and its host plant show significant overlap following the initiation of mimicry. Gianoli has argued this could represent a mechanism behindB. trifoliata's mimicry but still acknowledged that there are limitations to this hypothesis. While HGT commonly occurs between different species, it takes many years and manifests in discrete events. Additionally, HGT between plants is most commonly observed in cases of parasitism, whichB. trifoliata does not engage in.[19]
In a 2021 study published in the journalPlant Signaling & Behavior, Felipe Yamashita and Jacob White claimed thatB. trifoliata may employ a primitive form of vision to identify and mimic their hosts. This hypothesis is based upon 1905 and 1907 claims byGottlieb Haberlandt andFrancis Darwin, respectively, that some plants use 'ocelli' or lens-like cells to focus light onto other light sensitive cells. In this study,B. trifoliata was observed mimicking the leaf shapes of plastic plants, and researchers refinedHaberlandt andDarwin's ocelli hypothesis, claiming thatB. trifoliata may be using convex shaped lenses in epidermal tissue that can detect light and "see" the shapes of nearby leaves.[24] They further proposed that,B. trifoliata processes that information through an unknown means, possibly throughneuron-like structures in order to initiate mimicry.[18][23] The study also found that non-mimetic leaves have more free-endveinlets and identified the hormoneauxin as a possible mediator in changes to leaf morphology.[24]
This paper received substantial media coverage, was praised byF1000's Faculty Opinions, and went viral on the social media platformTikTok following its release.František Baluška, a plant biologist andeditor-in-chief ofPlant Signaling & Behavior, praised this hypothesis, and claimed that rootskototropism and photoreceptive cells inalgae were analogous mechanisms for "plant sight". However, the paper's conclusions have largely been met with skepticism by scientists. Criticisms of the paper include poor methodology, White's lack of a scientific background, and possibleconflicts of interest between Baluška and Yamashita.[18][23] The research was awarded the 2024Ig Nobel Prize for botany.[25]
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TheBoquila genus isendemic to thetemperate rainforests,nothofagus forests, andevergreen forests of southern Argentina and Chile, ranging fromCauquenes toChiloe.[13][4]B. trifoliata is most commonly found between 100 metres (330 ft) to 600 metres (2,000 ft) in elevation.[13] Unlike many other species of vines,B. trifoliata is notparasitic. Instead, it only attaches to trees for protection and structure, sometimes forming thickets over 6 metres (20 ft) in height.B. trifoliata can survive temperatures as low as −8 °C (18 °F) and prefers soil rich inhumus. The species is resistant towilting, but generally prefers to grow in shaded environments.[4][15][13]
The stems are used locally inbasketry and in rope making. The leaf juice was historically used by local tribes to treat sore eyes and was once believed to be anaphrodisiac. The plant is also usedornamentally and the berries are edible.[13] Stems are often cut in the summer and rooted incold frames as ameans of propagation.[15]
