Protocarnivorous plant

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Mucilage-tipped bracts and immature flower of Passiflora foetida, a protocarnivorous plant. Passiflora bud.jpg
Mucilage-tipped bracts and immature flower of Passiflora foetida , a protocarnivorous plant.

A protocarnivorous plant (sometimes also paracarnivorous, subcarnivorous, or borderline carnivore), according to some definitions, traps and kills insects or other animals but lacks the ability to either directly digest or absorb nutrients from its prey like a carnivorous plant. The morphological adaptations such as sticky trichomes or pitfall traps of protocarnivorous plants parallel the trap structures of confirmed carnivorous plants.

Contents

Some authors prefer the term "protocarnivorous" because it implies that these plants are on the evolutionary path to true carnivory, whereas others oppose the term for the same reason. The same problem arises with "subcarnivorous". Donald Schnell, author of the book Carnivorous Plants of the United States and Canada, prefers the term "paracarnivorous" for a less rigid definition of carnivory that can include many of the possible carnivorous plants. [1]

The demarcation between carnivorous and protocarnivorous is blurred by the lack of a strict definition of botanical carnivory and ambiguous academic literature on the subject. Many examples of protocarnivorous plants exist, some of which are counted among the ranks of true carnivorous plants as a matter of historical preference. Further research into these plants' carnivorous adaptations may reveal that a few protocarnivorous plants do meet the more rigid definition of a carnivorous plant.

Historical observations

Charles Darwin postulated that Erica tetralix might be carnivorous Illustration Erica tetralix0.jpg
Charles Darwin postulated that Erica tetralix might be carnivorous

Historical observations of the carnivorous syndrome in plant species have been restricted to the more obvious examples of carnivory, such as the active trapping mechanisms of Drosera (the sundews) and Dionaea (Venus flytrap), though authors have often noted speculation about other species that may not be so obviously carnivorous. In one of the earlier publications on carnivorous plants, Charles Darwin had suggested many plants that have developed adhesive glands, such as Erica tetralix , Mirabilis longifolia , Pelargonium zonale , Primula sinesis , and Saxifraga umbrosa , may indeed be carnivorous but little research has been done on them. Darwin himself only mentioned these species in passing and did not follow through with any investigation. [2] [3] Adding to the small but growing list, Francis Lloyd provided his own list of species suspected of carnivory in his 1942 book on carnivorous plants, though these species and their potential were only mentioned in the introduction. [4] Later, in a 1981 review of the literature, Paul Simons rediscovered Italian journal articles from the early 1900s that identified several additional sticky species that digested insect prey. Simons was surprised to find these articles lacking in the literature cited sections of many modern books and articles on carnivorous plants, suggesting that academic research has treated Lloyd's 1942 book as the authoritative and comprehensive source on pre-1942 research on the carnivorous syndrome. [5]

Defining carnivory

Debate about what criteria a plant must meet to be considered carnivorous has yielded two proposed definitions: one with strict requirements and the other less restrictive.

Darlingtonia californica does not produce its own digestive enzymes. Darlingtonia californica ne1.JPG
Darlingtonia californica does not produce its own digestive enzymes.

The strict definition requires that a plant must possess morphological adaptations that attract prey through scent or visual cues, capture and retain prey (e.g., the waxy scales of Brocchinia reducta or downward facing hairs of Heliamphora prevent escape), digest the dead prey through enzymes produced by the plant, and absorb the products of digestion through specialized structures. The presence of commensals is also listed as strong evidence of a long evolutionary history of carnivory. [6] By this definition, many sun pitcher plants (Heliamphora) [7] and the cobra lily (Darlingtonia californica) [8] would not be included on a roster of carnivorous plants because they rely on symbiotic bacteria and other organisms to produce the necessary proteolytic enzymes.

The broader definition differs mainly in including plants that do not produce their own digestive enzymes but rely on internal food webs or microbes to digest prey, such as Darlingtonia and some species of Heliamphora . The original definition of botanical carnivory, set out in Givnish et al. (1984), [9] required a plant to exhibit an adaptation of some trait specifically for the attraction, capture, or digestion of prey while gaining a fitness advantage through the absorption of nutrients derived from said prey. Upon further analysis of genera currently considered carnivorous, botanists widened the original definition to include species that use mutualistic interactions for digestion.

Both the strict and broad definitions require absorption of the digested nutrients. The plant must receive some benefit from the carnivorous syndrome; that is, the plant must display some increase in fitness because of the nutrients obtained from its carnivorous adaptations. Increased fitness might mean improved growth rate, increased chance of survival, higher pollen production or seed set. [9]

Degrees of carnivory

Plumbago auriculata, showing the abundant trichomes present on the calyces. Colpfl22edited.jpg
Plumbago auriculata , showing the abundant trichomes present on the calyces.

One prevailing idea is that carnivory in plants is not a black and white duality, but rather a spectrum from strict non-carnivorous photoautotrophs (a rose, for example) to fully carnivorous plants with active trapping mechanisms like those of Dionaea or Aldrovanda . However, passive traps are still considered fully carnivorous. Plants that fall between the definitions in the strict carnivorous/non-carnivorous demarcation can be defined as being protocarnivorous.

It is thought that these plants that have evolved protocarnivorous habits typically reside in habitats where there is a significant nutrient deficiency, but not the severe deficiency in nitrogen and phosphorus seen where true carnivorous plants grow. [10] The function of the protocarnivorous habit, however, need not be directly related to lack of nutrient access. Some classic protocarnivorous plants represent convergent evolution in form but not necessarily in function. Plumbago , for example, possesses glandular trichomes on its calyces that structurally resemble the tentacles of Drosera and Drosophyllum . [11] The function of the Plumbago tentacles is, however, disputed. Some contend that their function is to aid in pollination, adhering seeds to visiting pollinators. [12] Others note that on some species ( Plumbago auriculata ), small, crawling insects have been trapped in the Plumbago's mucilage, which supports the conclusion that these tentacles could have evolved to exclude crawling insects and favor flying pollinators for greater seed dispersal or perhaps for protection against crawling insect predators. [11]

Trapping mechanisms

There are visible parallels between the trapping mechanisms of carnivorous plants and protocarnivorous plants. Plumbago and other species with glandular trichomes resemble the flypaper traps of Drosera and Drosophyllum. The pitfall traps of protocarnivorous plants, such as some Heliamphora species and Darlingtonia californica, are so similar to those of true carnivorous plants that the only reason they may be considered protocarnivorous instead of carnivorous is that they do not produce their own digestive enzymes. There are also protocarnivorous bromeliads that form a pitfall trap in an "urn" of rosetted leaves that are held together tightly. There are also other plants that produce a sticky mucilage not necessarily associated with a tentacle or glandular trichome, but instead can be described more like a slime capable of trapping and killing insects.

Flypaper traps

A protocarnivorous flypaper trap below the flowers of Stylidium productum. Stylidium productum.JPG
A protocarnivorous flypaper trap below the flowers of Stylidium productum .

Dr. George Spomer of the University of Idaho has discovered protocarnivorous activity and function in several glandular plant species, including Cerastium arvense , Ipomopsis aggregata , Heuchera cylindrica , Mimulus lewisii , Penstemon attenuata , Penstemon diphyllus , Potentilla glandulosa var. intermedia, Ribes cereum , Rosa nutkana var. hispida, Rosa woodsii var. ultramontana, Solanum tuberosum , Stellaria americana , and Stellaria jamesiana . These species tested positive for protease activity, though it is unclear whether the protease is produced by the plant or by surface microbes. Two other species evaluated by Dr. Spomer, Geranium viscosissimum and Potentilla arguta , exhibited protease activity and were further examined with 14C-labeled algal protein for nutrient absorption activity. Both of these latter species displayed an ability to digest and absorb the labeled protein. [13]

Other plants that are considered to be protocarnivorous have sticky trichomes on some surface, such as the flower scape and bud of Stylidium and Plumbago , [14] the bracts of Passiflora , and leaves of Roridula . The trichomes of Stylidium, which appear below the flower, have been known to trap and kill small insects since their discovery several centuries ago, but their purpose remained ambiguous. In November 2006, Dr. Douglas Darnowski published a paper describing the active digestion of proteins when they come in contact with a trichome of a Stylidium species grown in aseptic tissue culture, proving that the plant, rather than the surface microbes, was the source of protease production. [15] Darnowski asserts in that paper that given this evidence, Stylidium species are properly called carnivorous, though in order to fulfill the strict definition of carnivory it needs to be proven that they are capable of absorbing nutrients derived from prey and that this adaptation gives the plants some competitive advantage.

The glandular hairs on the calyx of plants of the genus Plumbago have been proposed as a potential carnivorous adaptation. While these calyxes have long been considered as a seed dispersal mechanism, [16] many researchers have noted the entrapment of numerous ants and other small insects on the species Plumbago auriculata , [17] Plumbago europa , [18] Plumbago indica , [19] and Plumbago zeylanica . [20] [ citation needed ] Studies on P. auriculata and P. indica detected potential protease activity from these glands, [19] but were inconsistent in detecting it. Energy-dispersive X-ray spectroscopy spectra of the glands on P. auriculata and P. zeylanica found that the glandular secretions were composed mainly of the elements C, O, Si, Mg, and Al. [21] One such species, P. europaea, has also been noted to kill small birds by covering them in sticky calyxes, causing them to be unable to fly and subsequently die. [22] A similar sticky-seed killing mechanism has been studied Pisonia grandis , but was concluded to not be a carnivorous adaptation. [23]

An assassin bug (Pameridea roridulae) on Roridula gorgonias, which obtains nutrients from its 'prey' via the droppings of the assassin bug. Pameridea.jpg
An assassin bug ( Pameridea roridulae ) on Roridula gorgonias , which obtains nutrients from its 'prey' via the droppings of the assassin bug.

Roridula has a more complex relationship with its prey. The plants in this genus produce sticky leaves with resin-tipped glands that look similar to those of larger Drosera . However, the resin, unlike mucilage, is unable to carry digestive enzymes. Therefore, Roridula species do not directly benefit from the insects they catch. Instead, they form a mutualistic symbiosis with species of assassin bugs that eat the trapped insects. The plant benefits from the nutrients in the bugs' feces. [24]

Likewise, the sticky, modified bracts of passion flowers of the section Dysosmia have notable glandular bracts that surround flowers and forming fruit. [25] While this has long been discussed as a defense mechanism, studies of Passiflora foetida have investigated them for potential carnivorous abilities. A 1995 paper published in the Journal of Biosciences detailed the evidence that the glandular bracts played a distinct role in defense of the flower and were also capable of digesting captured prey and absorbing the nutrients. [26] Various authors have questioned the methods and conclusions of this paper. [27] Further studies using on the glandular bracts using histochemical tests have confirmed the presence of enzymes in both Passiflora foetida and Passiflora sublanceolata . [28]

Various plants of the Martyniaceae family have been considered crude flypaper protocarnivores. Early publications identified the entrapment of numerous insects on the glandular hairs covering the stems and leaves of Martynia annua , [17] Proboscidea louisiana , [29] Proboscidea parviflora , [30] and Ibicella lutea . [31] Early, rudimentary studies showed that placed bits of food—beef and hard-boiled egg white broke down when placed on the leaf surface ofP. louisiana [32] and I. lutea, [31] respectively. Despite this, more recent studies have suggested that there are no detectable proteases on the leaves of I. lutea and P. louisiana [33] and no detectable phosphatases or uptake of N, P, K, Mg from dried flies places on I. lutea and P. parviflora. [34] Observations have suggested that there may be a digestive mutualism between carnivorous insects and the sticky plant surface similar to Roridula . [35] A similar relationship has been identified in many other sticky desert plants and concluded to be a passive defense mechanism. [36]

Pitfall traps

The water reservoir of Dipsacus fullonum, a pitfall trap. Dipsacus-fullonum-water-storage.jpg
The water reservoir of Dipsacus fullonum , a pitfall trap.

The pitfall traps of protocarnivorous plants are identical to those of carnivorous plants in every way except in the plant's mode of digestion. The rigid definition of carnivory in plants requires digestion of prey by enzymes produced by the plant. Given this criterion, many of the pitfall trap plants commonly considered to be carnivorous would instead be classified as protocarnivorous. However, this is highly contentious and generally not reflected in current carnivorous plant phylogenies or literature. [37] [38] Darlingtonia californica [8] and several Heliamphora species do not produce their own enzymes, relying instead on an internal food web to break down the prey into absorbable nutrients. [7]

Another pitfall trap form unrelated to the Sarraceniaceae family are the urns of bromeliad leaves that are formed when leaves are tightly packed together in a rosette, collecting water and trapping insects. Unlike Brocchinia reducta , which has been proven to produce at least one digestive enzyme and can therefore be considered carnivorous, the epiphytic Catopsis berteroniana has little evidence supporting the claims that it is carnivorous. It is able to attract and kill prey and the trichomes on the surface of the leaves can absorb nutrients, but so far no enzyme activity has been detected. It may be that this plant also relies on an internal food web for soft tissue digestion. [39] The same could be said for Paepalanthus bromelioides , though it is a member of Eriocaulaceae and not a bromeliad. It also forms a central water reservoir that has adaptations to attract insects. It, like C. berteroniana, produces no digestive enzymes. [40]

Another potential protocarnivorous pitfall trap is a species of teasel, Dipsacus fullonum , which has been only suggested as a possible carnivore. Only one major study has examined D. fullonum for carnivory and no evidence of digestive enzymes or foliar nutrient absorption was revealed. [41]

Other

Capsella bursa-pastoris , Shepherd's purse, is another plant where the claim of carnivory is contested. This unique protocarnivorous plant is only capable of capturing and digesting prey during one stage of its life cycle. The seeds of the plant, when moistened, secrete a Mucilage that attracts and kills prey. There is also evidence of protease activity and absorption of nutrients. [42] [1] More recent studies have suggested that the plants may benefit from the feeding of Nematodes to the seeds of the plants, [43] but due to a small sample size such conclusions cannot be made. Other plants such as Descurainia pinnata , Descurainia sophia , Hirschfeldia incana , and Lepidium flavum were also noted to entrap small insects. [44] Mucilage production by seeds is fairly common in the plant kingdom and is typically associated with root and shoot penetration. Further work to identify the nutrient fluxes in this seed-insect system in-situ are required to understand any carnivorous aspects of this system.

Puya raimondii and Puya chilensis are two large arid bromeliads that have been suspected of being proto-carnivorous plants due to their entrapment of small animals in their spiny leaves. Puya raimondii was noted to have associated with numerous birds, some of which would become ensnared in the spiky foliage and die. It is hypothesized that this, as well as dropping from the birds who lived amongst the leaves, are a source of nutrients upon decomposition and subsequent foliage absorption by the plant. [45] Similarly, Puya chilensis was noted to ensnare livestock such as sheep who, unless rescued would degrade and feed the plant. [46] Despite this, the adaptations seen in Puya that lead to ensnarement of animals seems most likely to be a defense mechanism. [47]

Loss of carnivory

Nepenthes ampullaria is well-adapted to capture leaf litter. Nep amp 295.jpg
Nepenthes ampullaria is well-adapted to capture leaf litter.

A few plants that could be considered protocarnivorous or paracarnivorous are those that once had carnivorous adaptations but appear to be evolving or have evolved away from a direct prey relationship with arthropods and rely on other sources for obtaining nutrients. One example of such a phenomenon is the pitfall trap of Nepenthes ampullaria , a tropical pitcher plant. Although it retains its ability to attract, capture, kill, and digest insect prey, this species has acquired adaptations that appear to favor digestion of leaf litter. It could potentially be referred to as a detritivore. [48] Another tropical pitcher plant, Nepenthes lowii , is known to catch very few prey items compared to other Nepenthes. [49] Preliminary observations suggest that this particular species may have moved away from a solely (or even primarily) carnivorous nature and be adapted to "catching" the droppings of birds feeding at its nectaries. [48] [50] A 2009 study found that mature N. lowii plants derived 57–100% of their foliar nitrogen from treeshrew droppings. [51] [52]

Utricularia purpurea , a bladderwort, comes from another genus of carnivorous plants and may have lost its appetite for carnivory, at least in part. This species can still trap and digest arthropod prey in its specialized bladder traps, but does so sparingly. Instead, it harbors a community of algae, zooplankton, and debris in the bladders, giving rise to the hypothesis that the bladders of U. purpurea favor a mutualistic interaction in place of a predator-prey relationship. [53]

Evolution

The disciplines of ecology and evolutionary biology have presented several hypotheses on the evolution of carnivorous plants that may also apply to protocarnivorous plants. The name "protocarnivorous plant" itself suggests that these species are on their way to carnivory, though others may simply be an example of a defense-related adaptation, such as that found in Plumbago . [11] [12] Still others (Utricularia purpurea, Nepenthes ampullaria, and Nepenthes lowii) may be examples of carnivorous plants moving away from the carnivorous syndrome.

In his 1998 book, Interrelationship Between Insects and Plants, Pierre Jolivet only considered four species of plants to be protocarnivorous: Catopsis berteroniana, Brocchinia reducta , B. hectioides , and Paepalanthus bromeloides. Jolivet writes, "It is important to remember that all carnivorous plants are dicots and all protocarnivorous plants are monocots," though he does not explain why nor does he describe his reasons for excluding other dicotyledonous plants that are protocarnivorous. [54]

Notes

  1. 1 2 Schnell, 2002
  2. Darwin, 1875
  3. Roberts, Hattie R.; Warren, John M.; Provan, Jim (2018-07-04). "Evidence for facultative protocarnivory in Capsella bursa-pastoris seeds". Scientific Reports. 8 (1): 10120. Bibcode:2018NatSR...810120R. doi:10.1038/s41598-018-28564-x. ISSN   2045-2322. PMC   6031654 . PMID   29973685.
  4. Lloyd, 1942
  5. Simons, 1981
  6. The five rigid criteria of the carnivorous syndrome proposed by Juniper et al. (1989) and Albert et al. (1992).
  7. 1 2 Field studies of Heliamphora have determined that some species ( H. nutans , H. heterodoxa , H. minor , and H. ionasi ) do not produce their own digestive enzymes (Jaffe et al., 1992).
  8. 1 2 Hepburn et al. (1927) is referenced in Ellison and Farnsworth (2005) as the authoritative source on Darlingtonia's apparent lack of proteolytic enzymes. Ellison and Farnsworth (2005) also notes that Darlingtonia instead relies on "a food web of bacteria, protozoa, mites, and fly larvae" to break down captured prey (Naeem, 1988; Nielsen, 1990).
  9. 1 2 Givnish, T.J., Burkhardt, E.L., Happel, R.E., and Weintraub, J.D. (1984), "Carnivory in the bromeliad Brocchinia reducta, with a cost/benefit model for the general restriction of carnivorous plants to sunny, moist, nutrient-poor habitats", American Naturalist, 124 (4): 479–497, doi:10.1086/284289, JSTOR   2461590, S2CID   84947503 {{citation}}: CS1 maint: multiple names: authors list (link)
  10. Spoomer (1999) presented the argument that carnivorous plants may have evolved from protocarnivorous species when faced with a nutrient deficiency, noting the genetic evidence for multiple independent plant lines that evolved a fully carnivorous habit (Juniper et al., 1989; Albert et al., 1992).
  11. 1 2 3 Schlauer, 1997
  12. 1 2 Fahn and Werker, 1972
  13. Spomer, 1999
  14. Rachmilevitz and Joel, 1976
  15. Darnowski et al., 2006
  16. Fahn, A.; Werker, E. (1972). "Anatomical mechanisms of seed dispersal". Seed Biology: Importance, Development, and Germination: 151–221. doi:10.1016/B978-0-12-424301-9.50010-3. ISBN   9780124243019.
  17. 1 2 Beal, W. J. (1876). "Carnivorous Plants". The American Naturalist. 10 (10): 588–591. doi: 10.1086/271746 . S2CID   222324082.
  18. Heim, F (1898). The Biological Relations Between Plants and Ants.
  19. 1 2 Stoltzfus, A.; Suda, J.; Kettering, R.; Wolfe, A.; Williams, S. (2002). "Secretion of digestive enzymes in Plumbago". In Proceedings: The 4th International Carnivorous Plant Conference (203–207).
  20. Sayantan, Panda (2015). "Population structure and genetic diversity of the perennial medicinal shrub Plumbago". AoB Plants. 7: plv048. doi:10.1093/aobpla/plv048. PMC   4501514 . PMID   25957315.
  21. Chaudhari, S. S.; Chaudhari, G. S. (2017). "Comparative LM and SEM studies of glandular trichomes on the calyx of flowers of two species of Plumbago Linn". Plant Archives. 17 (2): 948–954.
  22. Purger, J. J.; Kletecki, E.; Trócsányi, B.; Muzinic, J.; Purger, D.; Széles, G. L.; Lanszki, J (2012). "The Common Leadwort Plumbago europaea L. as a natural trap for the wintering Goldcrests Regulus regulus: a case study from Adriatic islands". Journal of Biological Research. 17 (176).
  23. Burger, A. E. (2005). "Dispersal and germination of seeds of Pisonia grandis, an Indo-Pacific tropical tree associated with insular seabird colonies". Journal of Tropical Ecology. 21 (3): 263–271. doi:10.1017/S0266467404002159. S2CID   86457740.
  24. Hartmeyer (1998) described this phenomenon in the genus Roridula.
  25. Vanderplank, John (2013). "A REVISION OF PASSIFLORA SECTION DYSOSMIA: Passifloraceae". Curtis's Botanical Magazine. 3 (4): 318–387. doi:10.1111/curt.12050.
  26. Passiflora foetida bracts produce proteases and acid phosphatases (Radhamani et al., 1995).
  27. Chase, M. W.; Christenhusz, M. J.; Sanders, D.; Fay, M. F. (2009). "Murderous plants: Victorian Gothic, Darwin and modern insights into vegetable carnivory". Botanical Journal of the Linnean Society. 161 (4): 329–356. doi: 10.1111/j.1095-8339.2009.01014.x .
  28. de Lemos, R. C. C. (2017). "Anatomia, ultraestrutura e química das glândulas foliares de Passiflora L. (Passifloraceae)". Doutorado em Botânica, Universidade de São Paulo.
  29. Crawford, J. (1884). "Martynia and its Hublme Servants". American Journal of Pharmacy (1835–1907): 641.
  30. Thieret, J. W. (1977). "The Martyniaceae in the southeastern United States". Journal of the Arnold Arboretum. 58 (1): 25–39. doi: 10.5962/bhl.part.29234 .
  31. 1 2 Mameli, E (1916). "Ricerche anatomiche, fisiologiche e biologiche sulla Martynia lutea Lindl". Atti dell'Universita di Pavia. 2 (16).
  32. Fermi, C; Buscaglioni, D (1899). "The proteolytic enzymes in the plant kingdom". ZBL. Bakt., II. Abbot (5): 24–27.
  33. Rice, B. (1998). "Testing the appetites of Ibicella and Drosophyllum". Carnivorous Plant Newsletter. 28 (1): 40–43. doi: 10.55360/cpn282.br358 . S2CID   248093742.
  34. Płachno, B. J.; Adamec, L.; Huet, H. (2009). "Mineral nutrient uptake from prey and glandular phosphatase activity as a dual test of carnivory in semi-desert plants with glandular leaves suspected of carnivory". Annals of Botany. 104 (4): 649–654. doi: 10.1093/aob/mcp155 . PMC   2729641 . PMID   19556266.
  35. Rice, B (2008). "Reassessing commensal-enabled carnivory in Proboscidea and Ibicella". Carnivorous Plant Newsletter. 37 (1): 15–19. doi: 10.55360/cpn371.br188 . S2CID   247121501.
  36. Krimmel, Billy A., and I. S. Pearse (2013). "Sticky plant traps insects to enhance indirect defence". Ecology Letters. 16 (2): 219–224. Bibcode:2013EcolL..16..219K. doi:10.1111/ele.12032. PMID   23205839.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  37. Givnish, T. J. (2015). "New evidence on the origin of carnivorous plants". PNAS. 112 (1): 10–11. Bibcode:2015PNAS..112...10G. doi: 10.1073/pnas.1422278112 . PMC   4291624 . PMID   25538295.
  38. Pavlovic, A., Saganova, M. (2015). "A novel insight into the cost-benefit model for the evolution of botanical carnivory". Annals of Botany. 115 (7): 1075–1092. doi:10.1093/aob/mcv050. PMC   4648460 . PMID   25948113.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  39. Frank and O'Meara (1984) detected a higher trapping rate in C. berteroniana compared to three other tank bromeliads. They also noted that commensals lived unharmed within the tank. Benzing et al. (1976) discovered that C. berteroniana is capable of absorbing radioisotope-tagged amino acids through the leaves.
  40. Pierre Jolivet (1998) suggests that this plant also relies on its internal food web to break down the soft tissues of prey for absorption.
  41. Christy (1923) did note that the fluid collected in the basin formed by the leaves has a lower surface tension, which could be an adaptation to kill prey.
  42. Barber, 1978
  43. Roberts, H. R., Warren, J. M., & Provan, J. (2018). "Evidence for facultative protocarnivory in Capsella bursa-pastoris seeds". Scientific Reports. 8 (1): 10120. Bibcode:2018NatSR...810120R. doi:10.1038/s41598-018-28564-x. PMC   6031654 . PMID   29973685.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  44. Reeves, E. L., & Garcia, C. (1969). "Mucilaginous seeds of the Cruciferae family as potential biological control agents for mosquito larvae". Mosq. News (29): 601–607.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  45. Rees, W. E., & Roe, N. A. (1980). "Puya raimondii (Pitcairnioideae, Bromeliaceae) and birds: an hypothesis on nutrient relationships". Canadian Journal of Botany. 58 (11): 1262–1268. doi:10.1139/b80-157.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  46. "Sheep-Eating Plant Opens Up After 15 Years : DNews". DNews. Archived from the original on 2015-11-21. Retrieved 2015-11-30.
  47. Chase, M. W., Christenhusz, M. J., Sanders, D., & Fay, M. F (2009). "Murderous plants: Victorian Gothic, Darwin and modern insights into vegetable carnivory". Botanical Journal of the Linnean Society. 161 (4): 329–356. doi: 10.1111/j.1095-8339.2009.01014.x .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  48. 1 2 Clarke, 2001
  49. Adam, 1997
  50. Clarke, 1997
  51. Clarke et al., 2009
  52. Fountain, 2009
  53. Richards (2001) did an extensive study in the field on U. purpurea and noted that trapping rates of the usual Utricularia prey were significantly lower than in other species in the genus.
  54. Jolivet, 1998

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Droseraceae is a family of carnivorous flowering plants, also known as the sundew family. It consists of approximately 180 species in three extant genera. Representatives of the Droseraceae are found on all continents except Antarctica.

<i>Nepenthes</i> Tropical pitcher plants

Nepenthes is a genus of carnivorous plants, also known as tropical pitcher plants, or monkey cups, in the monotypic family Nepenthaceae. The genus includes about 170 species, and numerous natural and many cultivated hybrids. They are mostly liana-forming plants of the Old World tropics, ranging from South China, Indonesia, Malaysia, and the Philippines; westward to Madagascar and the Seychelles (one); southward to Australia (four) and New Caledonia (one); and northward to India (one) and Sri Lanka (one). The greatest diversity occurs on Borneo, Sumatra, and the Philippines, with many endemic species. Many are plants of hot, humid, lowland areas, but the majority are tropical montane plants, receiving warm days but cool to cold, humid nights year round. A few are considered tropical alpine, with cool days and nights near freezing. The name "monkey cups" refers to the fact that monkeys were once thought to drink rainwater from the pitchers.

<span class="mw-page-title-main">Venus flytrap</span> Species of carnivorous plant

The Venus flytrap is a carnivorous plant native to the temperate and subtropical wetlands of North Carolina and South Carolina, on the East Coast of the United States. Although various modern hybrids have been created in cultivation, D. muscipula is the only species of the monotypic genus Dionaea. It is closely related to the waterwheel plant and the cosmopolitan sundews (Drosera), all of which belong to the family Droseraceae. Dionaea catches its prey—chiefly insects and arachnids—with a "jaw"-like clamping structure, which is formed by the terminal portion of each of the plant's leaves; when an insect makes contact with the open leaves, vibrations from the prey's movements ultimately trigger the "jaws" to shut via tiny hairs on their inner surfaces. Additionally, when an insect or spider touches one of these hairs, the trap prepares to close, only fully enclosing the prey if a second hair is contacted within (approximately) twenty seconds of the first contact. Triggers may occur as quickly as 110 of a second from initial contact.

<i>Genlisea</i> Genus of carnivorous plants

Genlisea is a genus of carnivorous plants also known as corkscrew plants. The 30 or so species grow in wet terrestrial to semi-aquatic environments distributed throughout Africa and Central and South America. The plants use highly modified underground leaves to attract, trap and digest minute microfauna, particularly protozoans. Although suggested a century earlier by Charles Darwin, carnivory in the genus was not proven until 1998.

<i>Heliamphora</i> Genus of carnivorous plants

The genus Heliamphora contains 24 species of pitcher plants endemic to South America. The species are collectively known as sun pitchers, based on the mistaken notion that the heli of Heliamphora is from the Greek helios, meaning "sun". The name instead derives from the Greek helos, meaning "marsh", so a more accurate translation of their scientific name would be marsh pitcher plants. Species in the genus Heliamphora are carnivorous plants that consist of a modified leaf form that is fused into a tubular shape. They have evolved mechanisms to attract, trap, and kill insects; and control the amount of water in the pitcher. At least one species produces its own proteolytic enzymes that allows it to digest its prey without the help of symbiotic bacteria.

<i>Passiflora foetida</i> Species of carnivorous plant

Passiflora foetida is a species of passion flower that is native to the southwestern United States, Mexico, the Caribbean, Central America, and much of South America. It has been introduced to tropical regions around the world, such as Southeast Asia, South Asia, Hawaii, Africa, and The Maldives. It is a creeping vine like other members of the genus, and yields an edible fruit. The specific epithet, foetida, means "stinking" in Latin and refers to the strong aroma emitted by damaged foliage.

<i>Darlingtonia californica</i> Species of carnivorous plant

Darlingtonia californica —also called the California pitcher plant, the Oregon pitcher plant, cobra lily or cobra plant—is a species of carnivorous plant in the new world pitcher plant family, Sarraceniaceae. It is the sole species within its monotypic genus, Darlingtonia. The cobra lily is native to Northern California and Oregon, in the western United States, where the climate—while typically thought of as cool and humid—may be quite arid for many months of the year, more so than many carnivorous or pitcher plant genera could feasibly survive. However, the cobra lily has evolved into life along the West Coast and in the lower Pacific Northwest through its carnivorous adaptions, where it may be found near bogs, vernal pools, on forested rocky slopes, creeks, or near seeps with cold running water, usually on serpentine soils. It has even been observed growing in drainage ditches or on the sides of roads. Despite being fairly commonly cultivated, Darlingtonia is designated as uncommon due to its rarity in the field.

<i>Roridula</i> Insect-trapping shrublet from South Africa

Roridula is a genus of evergreen, insect-trapping shrubs, with two species, of about 1⅓–2 m. It is the only genus in the family Roridulaceae. It has thin, woody, shyly branching, upright, initially brown, later grey stems, with lance- to awl-shaped leaves crowded at their tips. The star-symmetrical flowers consist from the outside in of five, green or reddish, free sepals, alternating with five white, pink or purple, free petals. Further to the middle and opposite the sepals are five stamens with the anthers initially kinked down. These suddenly flip up if the nectar-containing swelling at its base is being touched. The center of the flower is occupied by a superior ovary. The leaves and sepals carry many sticky tentacles of different sizes, that trap insects. Roridula does not break down the insect proteins, but bugs of the genus Pameridea prey on the trapped insects. These later deposit their feces on the leaves, which take up nutrients from the droppings. The species can be found in the Western Cape province of South Africa. They are commonly known as dewstick or fly bush in English and vlieëbos or vlieëbossie in Afrikaans.

<i>Catopsis berteroniana</i> Species of carnivorous plant

Catopsis berteroniana, commonly known as the powdery strap airplant or the lantern of the forest, is an epiphytic bromeliad thought to be a possible carnivorous plant, similar to Brocchinia reducta, although the evidence is equivocal. Its native range is from southern Florida to southern Brazil. It generally grows on the unshaded twigs of trees, and has been shown experimentally to trap more insects in its tank than other bromeliads of comparable size. There are several other species in the genus, none of which is believed to be carnivorous.

<i>Drosera capensis</i> Species of carnivorous plant

Drosera capensis, commonly known as the Cape sundew, is a small rosette-forming carnivorous species of perennial sundew native to the Cape in South Africa. Because of its size, easy-to-grow nature, and the copious amounts of seed it produces, it has become one of the most common sundews in cultivation, and thus, one of the most frequently introduced and naturalised invasive Drosera species.

<i>Stylidium</i> Genus of plants

Stylidium is a genus of dicotyledonous plants that belong to the family Stylidiaceae. The genus name Stylidium is derived from the Greek στύλος or stylos, which refers to the distinctive reproductive structure that its flowers possess. Pollination is achieved through the use of the sensitive "trigger", which comprises the male and female reproductive organs fused into a floral column that snaps forward quickly in response to touch, harmlessly covering the insect in pollen. Most of the approximately 300 species are only found in Australia, making it the fifth largest genus in that country. Triggerplants are considered to be protocarnivorous or carnivorous because the glandular trichomes that cover the scape and flower can trap, kill, and digest small insects with protease enzymes produced by the plant. Recent research has raised questions as to the status of protocarnivory within Stylidium.

<i>Geranium viscosissimum</i> Species of flowering plant

Geranium viscosissimum, commonly known as the sticky purple geranium, is a perennial in the flowering plant family Geraniaceae. It is thought to be a protocarnivorous plant.

Colura zoophaga is a species of epiphytic liverwort that is endemic to the African highlands, specifically parts of Kenya. It belongs to the genus Colura, which has been hypothesized to be carnivorous as early as 1893. It is a recently described species that was the subject of the first scientific study aimed at investigating the allegations of carnivory in liverworts.

<span class="mw-page-title-main">Carnivorous plant</span> Plants that consume animals

Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods, and occasionally small mammals and birds. They still generate all of their energy from photosynthesis. They have adapted to grow in waterlogged sunny places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs. They can be found on all continents except Antarctica, as well as many Pacific islands. In 1875, Charles Darwin published Insectivorous Plants, the first treatise to recognize the significance of carnivory in plants, describing years of painstaking research.

<i>Pinguicula elizabethiae</i> Species of carnivorous plant

Pinguicula elizabethiae is a perennial rosette-forming insectivorous herb native to the Mexican states of Querétaro and Hidalgo. A species of butterwort, it forms summer rosettes of flat, succulent leaves up to 5 centimeters (4 in) long, which are covered in mucilaginous (sticky) glands that attract, trap, and digest arthropod prey. Nutrients derived from the prey are used to supplement the nutrient-poor substrate that the plant grows in. In the winter the plant forms a non-carnivorous rosette of small, fleshy leaves that conserves energy while food and moisture supplies are low. Single purple flowers appear between July and October on upright stalks up to 75 millimeters long.

<i>Ibicella lutea</i> Species of carnivorous plant

Ibicella lutea is a species of flowering plant known by the common name yellow unicorn-plant. It grows in dry conditions, such as those in desert regions. It is native to South America, but has become established as a non-native species in various semi-arid regions around the world, including Southern Africa and the Central Valley of California. The plant is aromatic, with an unpleasant scent. It produces short, glandular hairs over most of its aerial surfaces and is coated in sticky resin. Insects often become stuck in the slimy exudate and die, but the plant does not have digestive enzymes and does not absorb nutrients from the insects. The plant can be considered protocarnivorous, but it is not carnivorous.

<i>Pinguicula</i> Genus of flowering plants in the family Lentibulariaceae

Pinguicula, commonly known as butterworts, is a genus of carnivorous flowering plants in the family Lentibulariaceae. They use sticky, glandular leaves to lure, trap, and digest insects in order to supplement the poor mineral nutrition they obtain from the environment. Of the roughly 80 currently known species, 13 are native to Europe, 9 to North America, and some to northern Asia. The largest number of species is in South and Central America.

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