Saltmarsh Ribbonwood / Plagianthus divaricatus
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| Saltmarsh ribbonwood | |
|---|---|
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Malvales |
| Family: | Malvaceae |
| Genus: | Plagianthus |
| Species: | P. divaricatus
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| Binomial name | |
| Plagianthus divaricatus J.R.Forst. & G.Forst.
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Plagianthus divaricatus or saltmarsh ribbonwood is a plant that is endemic to New Zealand. The Māori name is makaka. Other common names it is known by marsh ribbonwood, Houi and Runa.[1][2]
It was first described by J. R. Forst and G. Forst in 1776.[1][2]
Plagianthus divaricatus is an upright shrub with closely interwoven branches. The shrub is found in coastal environments in areas with salt swamp, sandy banks and throughout estuaries.[3]
Description
editPlagianthus divaricatus or salt-marsh ribbonwood is a bushy shrub endemic to New Zealand with thin twiggy intertwined stems that have small clusters of narrow leaves. Its branches are divaricate in form and it can reach up to 3 m tall.[1] Its twigs have small star-shaped hairs when looked at under a magnifying lens.[4] The leaves are small and narrow, reaching 5-20 mm long and 0.5-2 mm wide.[4] In spring it produces masses of small cream five petaled flowers. Its flowers are creamy white with purple tinged edges and are small and drooping. It has small white fruit, approximately 5 mm wide. It hybridises with lowland ribbonwood (Plagianthus regius), which produces tall, bushy, deciduous shrubs.[5] The leaves of the hybrid are grey-green, wider, and flatter than P. divaricatus.[5]
Range
editPlagianthus divaricatus is endemic to New Zealand. The Plagianthus genus contains only two species, P. regius and P. divaricatus, which are both endemic to New Zealand and the Chatham Islands. Plagianthus divaricatus is present across New Zealand’s North and South Islands, as well as the Chatham Islands and Stewart Island. It is found on both the west and east coasts in sheltered coastal and estuarine areas or inland off stony beaches. It is also likely to be as far south as the Dusky Sound in Fiordland.[4]
Habitat Preferences
editPlagianthus divaricatus is found in coastal environments, such as in coastal wetlands, sandy banks and throughout estuaries. It grows inland along estuarine waterways.[5] [6] It is also known to grow off from stony beaches.[4] It is predominantly a wetland plant but can occasionally be found in upland areas.[1] Plagianthus divaricatus is commonly found growing with; Olearia solandri, Coprosma propinqua and Muehlenbeckia complexa.[6]
Soil Preferences
editPlagianthus divaricatus is halophytic, meaning it prefers soils with high salinity and is hydrophytic, meaning it prefers to grow in a wet environment of highly saturated soil, though it is occasionally found growing in dryer areas.[6] It is tolerant to cold and warm temperatures and is present across the entire country.[7]
Life-cycle
editThe flowers of Plagianthus divaricatus are creamy or whitish edged with purple. Only the male flowers are sweet smelling. The flowers are produced in early spring from September to October.[8] Plagianthus divaricatus is also known to germinate better in lower and higher saline conditions compared to other similar estuarine species.[9] It is also quite a cold tolerant species[7], which could be due to its divaricating nature which Diels in 1897 proposed as an evolutionary adaptation of subtropical genera in response to the colder temperatures of the glacial periods.[10]
Associated Fauna
editP. divaricatus hosts many forms of animals, including many herbivorous and parasitic insects, which feed on it.
Invertebrate Herbivores & Pollinators
editMyzus persicae an aphid present on P. divaricatus.[11] Hoherius meinertzhageni is a beetle that tunnels in the dead wood of P. divaricatus.[11] Two different plant hopper species Anzora unicolor (Grey-Winged Plant Hopper) and Batrachomorphus adventitiosus.[11] P. divaricatus is host to two gall mites. Aceri plagianthi which is endemic to New Zealand. It is only present on both P. regius & P.divaricatus. It causes similar deformities on the inflorescence as E. plaginus, as well as a white felty growth on the leaves. Eriophyes plaginus which is also endemic to New Zealand it is only present on both P. regius & P. divaricatus and causes deformities on the inflorescence and induces ‘witches' broom’ galls.[11] Aphis mellifera, the honeybee, pollinates the flowers of P. divaricatus.[11] Two species of mealybugs Paracoccus albatus and Pseudococcus hypergaeus.[11] A mirid sucking bug Halormus velifer which breeds on P. divaricatus and Romna scotti.[11] Many different species of moths are herbivores of P. divaricatus. Chloroclystis inductata its caterpillars feed on the flowers. Caterpillars of Graphania scutata, Harmologa oblongana, Liothula omnivora (Case Moth), Pseudocoremia lactiflua and Stigmella aigialeia feed on the leaves of P. divaricatus.[11] A wide variety of scale insect species are also present on P. divaricatus. Aphenochiton inconspicuous , Aspidiiotus nerii , Hemiberlesia lataniae , Hemiberlesia rapax, Leucaspis sp. (Tahuna Torea) which lives on the stems of P. divaricatus and Saissetia oleae.[11] One sucking insect species Scolypopa australis.[11] And lastly for invertabrates, one weevil species Peristoreus australis whose larvae are reared from the male flowers.[11]
Seed Dispersal
editThe seed dispersal of P. divaricatus is currently understudied, but common genera with which it is associated with such as Coprosma and Muehlenbeckia, even specifically C. propinqua and M. complexa, have their seeds dispersed by geckos.[12][13] As geckos are omnivores, they eat a wide variety of things and when fruits are available, they will regularly consume fruits, making them an important seed disperser.[14] Thus, it is likely that P. divaricatus is similarly dispersed as it has small fleshy fruit like that of Coprosma and Muehlenbeckia, as well specifically being found in association with C. propinqua and M. complexa.
Vertebrate Browsers
editOne theory for the high numbers of divaricating plants in New Zealand, a group which P. divaricatus belongs to, is as an ecological adaption for protection against moa browsing.[15] Therefore, sometime in the past, one of the primary herbivores of P. divaricatus could have been moa resulting in the plant evolving this twiggy shrublike appearance.
Other Information
editPlagianthus divaricatus has a chromosome count of 2n = 42.[1]
Plagianthus means oblique or lop-sided flower and divaricatus means spreading or interlacing.[1]
References
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- ^ a b c d e f NZPCN (2024). "Plagianthus Divaricatus". New Zealand Plant Conservation Network.
- ^ a b NZ Flora (2024). "Plagianthus Divaricatus". New Zealand Flora.
- ^ "Salt marsh ribbonwood, makaka". Taranaki Regional Council. Retrieved 2012-03-25.
- ^ a b c d Wilson, A.H; Galloway, T (1993). Small-leaved Shrubs of New Zealand. Christchurch, New Zealand: Manuka Press.
{{cite book}}: CS1 maint: date and year (link) - ^ a b c Allan, H.H (1961). Flora of New Zealand. Vol. I. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. Government Printer, Wellington.
- ^ a b c Singers, N.J.D; Rogers, G.M (2014). A classification of New Zealand's terrestrial ecosystems (PDF). Department of Conservation.
{{cite book}}: CS1 maint: date and year (link) - ^ a b Harris, W; Cadic, A; Decourtye, L (1998). "The acclimatization and selection of New Zealand plants for ornamental use in Europe". In XIX International Symposium on Improvement of Ornamental Plants. 508: 191–196.
- ^ Wagstaff, S; Tate, J (2011). "Phylogeny and Character Evolution in the New Zealand Endemic Genus Plagianthus (Malveae, Malvaceae)". Systematic Botany. 36 (2): 405–418.
- ^ Partridge, T.R; Wilson, J.B (1987). "Germination in relation to salinity in some plants of salt marshes in Otago, New Zealand". New Zealand Journal of Botany. 25 (2): 255–261.
- ^ McGlone, M.S; Webb, C.J (1981). "Selective Forces Influencing the Evolution of Divaricating Plants". New Zealand Journal of Ecology. 4: 20–28.
- ^ a b c d e f g h i j k Landcare Research (2024). "Herbivores associated with a host plant". Landcare Research, Manaaki Whenua. Retrieved April, 2024.
{{cite web}}: Check date values in:|access-date=(help) - ^ Whitaker, A.H (1987). "The roles of lizards in New Zealand plant reproductive strategies". New Zealand Journal of Botany. 25 (2): 315–328.
- ^ Wotton, D.M; Drake, D.R; Powlesland, R.G; Ladley, J.J (2016). "The role of lizards as seed dispersers in New Zealand". Journal of the Royal Society of New Zealand. 46 (1): 40–65.
- ^ van Winkel, D; Baling, M; Hitchmough, R (2018). Reptiles and Amphibians of New Zealand. A Field Guide. Auckland, New Zealand: Auckland University Press.
{{cite book}}: CS1 maint: date and year (link) - ^ Greenwood, R.M; Atkinson, I.A.E (1977). "Evolution of divaricating plants in New Zealand in relation to moa browsing". Proceedings (New Zealand Ecological Society). 24: 21–33.