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Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Cyperaceae
Genus: Carex
Species:
C. secta
Binomial name
Carex secta
Boott


Carex secta is a sedge endemic to New Zealand. The Māori name is makura amongst others.

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Carex secta growing at the western end of Lake Clearwater in Canterbury, New Zealand

Māori Names

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Makura, Mārū, mātā, mātātā, Pūkio, Pūrei, Pūreirei, Pūrekireki[1]

Description

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Carex secta has a tussock-like form atop a trunk-like base. It described by Robert Laing [2] as having “blackened stumps about two feet high, bearing on their summits drooping brushes of long, coarse, green, or tawny threads”. Multiple sources list the plant as having a width of 1-1.5m and a height of 0.5-0.8m [3] [4]. The mature form of the plant has a trunk-like base, made up of matted rhizomes, old culm bases, and roots [3].

The leaves of the plant droop downwards with a width of 2-5mm [5]. They are a light green/yellow colour or dark green when in the constant shade[4]. The leaf is channeled (grooved running along the leaf) and very scabrid (having a rough surface)[5].

The plant contains drooping culms (stems that hold the fruit) 0.25-1m tall[4]. These culms have small spikelets at the branchlet ends[5]. They are trigonous (triangular in cross-section), similarly scabrid like the leaves, grooved, and have basal sheaths (purple/red coloured leaf structure that encircles the stem)[3]. At the end of the culms are inflorescence (clusters of spikelets). The inflorescence droop and are panicled with spikelets at the ends of the culms[4].

Another feature of Carex secta is the glumes (bracts below a spikelet in the inflorescence). These are pale brown with a straw-coloured midrib, ovate, and gradually tapered to a point[3]. The utricle (a sac that surrounds the fruit) is 2-5mm[3], dark brown with minor winged margins[4], and contains two stigmas[3].

Geographic Distribution and Habitat

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Natural global range

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Carex secta is endemic to New Zealand[4]. Endemic means that the species is unique to a particular region or place and found naturally nowhere else.

New Zealand range

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Carex secta is spread across New Zealand, found across the North Island to the South Island and even further south to Stewart Island[4]. Limited numbers also occur in the main Chatham Island[4].

Habitat

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Carex secta is widespread across wetlands and waterways [5]. Swampy grounds with moist soils provide ideal conditions for Carex secta to grow[6]. The geographic location of the wetlands can vary from coastal to alpine areas[4]. Within the wetlands, they will grow in water with a depth of up to 400mm[7]. Also, the light conditions in which they will grow can vary from open sunlight to light-shaded areas[7]. In shaded areas, it was 15% shorter and 62% narrower when compared with plants in full sun [8].

Life cycle/Phenology

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Carex secta flowers from late September to early December[4]; this can slightly vary depending on environmental conditions. It will typically fruit between October to March[4], ripening in the later months [7] before being dispersed. The seeds are dispersed via multiple methods: granivory (dispersal via seed predators’ consumption)[9], anemochory (dispersal of seeds via wind)[9], and hydrochory (dispersal via water)[7].

Germination of the seeds is dependent on the temperature, taking 3-4 weeks in summer (warmer conditions) and slower in colder conditions[7]. The seeds remain viable in the soil for a long time[10]. Because of this, when vegetation is cleared in wetlands, allowing light to reach ground level, the seeds will germinate in mass[10].

Environmental Conditions/Predators

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Environmental Conditions

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Carex secta prefers to grow in moist soils, but, can grow in most soil conditions[4]. A unique trait is that it is capable of growing in 300-400mm of standing water [7]. Carex secta prefers full sun but can tolerate shade in drier conditions [7]. In full sun, the leaves are a light green/yellow colour[4]. This is in contrast to the dark green colour the leaves turn when in shaded areas[4].

Predators, Parasites, and Diseases

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Carex secta has multiple endemic species of Lepidoptera (moths) and endemic Hemiptera (true bugs) that feed on it[11]. The Lepidoptera species (in their larval (caterpillar) stage) feed on the flowers/stems/blades of Carex secta[11]. These species include Diplopseustis perieresalis, Orocrambus angustipennis, Tmetolophota sulcana, Sagephora exsanguis, Megacraspedus sp.[11]. The Hemiptera species that feed on the leaves and seeds of the Carex secta include Rhopalimorpha obscura and Rhopalimorpha lineolaris[11].

The tussock form of Carex secta, raised above the water, provides excellent shelter and nesting sites for ground birds. Zapornia pusilla (Baillon's crake) is one of the bird species that nests within the plant[12]. Another species that has been recorded nesting in Carex secta is Botaurus poiciloptilus (Australasian bittern)[10].

Invasive exotic species, such as willows, are also a threat to the habitat of Carex secta [5]. The spread of invasive willows, with their large canopies, prevents light from reaching the ground level which limits the opportunities for the growth of Carex secta in what would otherwise be their ideal habitat.

Cultural Uses

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The leaves of Carex secta were used as thatch for the roofing of structures[13]. Māori had a proverb that described Carex secta: “He pūreirei whakamatuatanga. A faithful fatherly tuft of rushes.”[13]. The proverb referred to Carex secta as a trustworthy and reliable place where you could stop to rest during your journey across the swampy lands[13].

Sustainability

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Carex secta is a highly important species in the sustainable management of waterways in New Zealand. It provides multiple benefits to these highly crucial areas that flow across the landscape. One of the key benefits Carex secta provides is the stabilization of banks alongside streams; its extensive root system holds the soil together which prevents the banks from continuously eroding [8]. Another benefit stemming from the presence of Carex secta in waterways is the enhancement of water quality due to the reduction in sediment runoff from agriculture practices[10]. The drooping form of the leaves of Carex secta provides an additional benefit of shading over the water, helping to reduce eutrophication (which can be a major issue in some waterways).


References

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  1. ^ "Carex secta Boott". Biota of New Zealand. Landcare Research. Retrieved 24 March 2023.
  2. ^ Laing, Robert (1906). Plants of New Zealand. Whitcombe and Tombs.
  3. ^ a b c d e f Edgar, E; Moore, L. B (1970). Flora of New Zealand: volume II, indigenous tracheophyte (monocotyledons except graminae). Government Printer.
  4. ^ a b c d e f g h i j k l m n de Lange, P. J. "Carex secta fact sheet". New Zealand Plant Conservation Network. Retrieved 24 March 2023.
  5. ^ a b c d e Johnson, P; Brooke, P (1998). Wetland plants in New Zealand. Manaaki Whenua Press. Cite error: The named reference "Wetland plants in New Zealand" was defined multiple times with different content (see the help page).
  6. ^ Martin, W (1940). The flora of New Zealand. Whitcombe and Tombs.
  7. ^ a b c d e f g "Seed collection and propagation guide for grasses, sedges, lilies, flaxes, epiphytes and climbers". Department of Conservation. Ecosourced Waikato. 24 March 2023. Retrieved 24 March 2023. Cite error: The named reference "Seed collection and propagation guide for grasses, sedges, lillies, flaxes, epiphytes and climbers" was defined multiple times with different content (see the help page).
  8. ^ a b Haines, L; Margetts, J (2006). "How can urban riparian planting chime with residential garden design? An amenity planting trial for urban streamside's" (PDF). Royal New Zealand Garden Journal. 9 (2): 2-5. Cite error: The named reference "How can urban riparian planting chime with residential garden design? An amenity planting trial for urban streamside’s" was defined multiple times with different content (see the help page).
  9. ^ a b Thorsen, M; Dickinson, K; Seddon, P (2009). "Seed dispersal systems in the New Zealand flora". Perspectives in Plant Ecology, Evolution and Systematics. 11 (4): 285-309. doi:10.1016/j.ppees.2009.06.001. Cite error: The named reference "Seed dispersal systems in the New Zealand flora" was defined multiple times with different content (see the help page).
  10. ^ a b c d Clarkson, B; Peters, M (2012). Wetland restoration handbook: revegetation. Landcare Research.
  11. ^ a b c d "PlantSynz - Invertebrate herbivore biodiversity assessment tool: Database". plant-synz.landcareresearch.co.nz. Retrieved 2023-05-04.
  12. ^ O'Donnell, C. "Marsh crake / kotoreke". New Zealand Birds Online.
  13. ^ a b c "Carex secta. Carex spp. Sedges. Pūrei. Ngā Rauropi Whakaoranga". Manaaki Whenua - Landcare Research. 24 March 2023. Cite error: The named reference "Carex secta. Carex spp. Sedges. Pūrei. Ngā Rauropi Whakaoranga" was defined multiple times with different content (see the help page).